chemistry 6 - north penn school district / · web viewheat of fusion of ice ....25 qualitative...

Laboratory Manual Name:

Honors Chemistry Teacher: Period

ContentsPage

Lab Notebook Format……………………………………………………………………………….2-3

Experiments:1. Metric Measurements………………………………………………………………52. Specific Heat Investigation………………………………………………………...63. Density of Solids…………………………………………………………….…….74. Law of Conservation of Matter …………………………………………………...85. Physical and Chemical Changes…………………………………………………..10 6. Determining the Specific Heat of Iron…………………………………………....127. Temperature of a Bunsen Burner Flame…………………………………………..138. Law of Definite Composition……………………………………………………..149. Al Foil Lab………………………………………………………………………...1610. A Qualitative Analysis of Some Household Chemicals…………………….……..1711. Solutions Lab………………………………………………………………………2012. Absolute Zero Lab…………………………………………………………………2113. Precipitation Reactions: Formula Writing…………………………………….…...2314. Heat of Fusion of Ice……………………………………………………………....2515. Qualitative Analysis 1: Relative Solubilities……………………………………...2616. The Mole Lab……………………………………………………………………...3017. Hydrates…………………………………………………………………………...3218. Determining The Value of R.……………………………………………………...3419. Single and Double Replacement Reactions……………………………………….3520. Predicting Products………………………………………………………………..3721. Qualitative Analysis 2: Ag+, Hg2

2+, and Pb2+…………………………………….4022. Molar Volume of a Gas …………………………………………………………...4323. Percent Yield …………………………….………………………………………..45 24. Titration 1…………………………………………………………………….……4625. Titration 2…………………………………………………………...………….….4826. Titration 3……………………………………………………………………….…4927. Heat of a Reaction………………………………………………………………....5028. Determining Solution Concentration: Using a Spectrophotometer………………..5129. Flame Test …………………………………………………………………………53 30. Periodic Law……………...………………………………………………………..5431. Building Molecular Models…………………………………………………….….57

Names(s)____________________________________________Date Performed _______ Due Date ________

Lab Reporting and Assessment

Laboratory Notebook:

You are required have a marble composition book (any color) for lab work with your name and period number labeled on the front cover.

Designate the first two pages of the book (front and back of 1 page is fine) as a table of contents. Complete the table of contents as you do the labs throughout the year. Number the pages of your notebook in the top, right corner beginning with the table of contents page (page 1). Number the odd numbered pages only (even numbered pages will be the back of each page). You may write on one or both sides of the pages at your discretion. Be sure to include the page number that each lab starts in your table of contents.

All information entered into lab notebooks must be neat and logically organized.

It is highly recommended that lab notebooks be completed in pencil.

Pre-Lab Requirement: Before coming to class on the day of a lab, you must read the entire experiment and complete the following in your lab notebook:

Title of Lab (Be sure to include in the table of contents as well)

Date that the lab was performed

Pre-Lab Score: __________ Post-Lab Score:___________The score will be filled in by the teacher, but please have the labels and lines prepared.

Objective(s): State the purpose(s) of the experiment.

Procedure: Write, in a paragraph, a brief synopsis of the procedure conducted. Please note that this is a summary of the procedure. Do not simply copy the procedure. The intention is to provide a big picture understanding of the experiment. Do not include specific details.

Data and Results: Data are measurements and observations recorded during an experiment and results are calculations performed with these data. Prepare tables, in advance, for the recording of the necessary data to be collected during the experiment and the results to be calculated. The data and results sections may be combined into one table or separated at your discretion. Data and/or observations are to be recorded throughout the experiment in these tables prepared in advance.

Error Discussion Table: A table must be set up to discuss possible errors in the lab. The table should have 3 columns with the following headings: Procedure Step, Possible Error, and Effect on Objective (you should restate the objective here). The table must be completed before completing the lab. This may be a part of the post-lab discussion.

Point of emphasis: The number one cause of laboratory accidents, mistakes, and misunderstandings of experiments is not being prepared in advance. Therefore, the pre-lab requirement explained above is mandatory. Students who do not have their lab notebooks on the day of the lab or have not completed

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these requirements will not be permitted to do the experiment at that time and will not receive credit for the pre-lab requirements. The lab will have to be made up after school. The pre-lab requirements will still be in effect, but points will not be awarded. This is a lab safety issue, so exceptions to this policy will not be made. Students making up lab work after school due to absences will still be able to earn the credit for the pre-lab requirements.

Post-Lab Requirement: There will usually be some time at the conclusion of an experiment to begin the following:

Graph: (If applicable) Graphs must be done on graph paper and attention must be paid to neatness and precision. Be sure to include a title and properly label the axes. Cut the graph paper down to size and attach it to the appropriate page in your lab notebook.

Sample Calculations: Show the work for one of each calculation type. Solutions to calculations must be included in the results section. This section is simply for showing work. There should not be any important information in this section that does not appear in another section.

Questions: It is not necessary to recopy the question, but be sure that they are properly numbered. Work must be shown for calculation based questions.

Conclusion: State whether or not the objectives of the experiment were met. Support your conclusions with details from the experiment. For example, if the objective of an experiment is to determine the molar mass of an unknown, the determined molar mass must be stated in the conclusion. Also, it is appropriate to mention sources of error in the conclusion except when there is a specific question regarding error.

Lab Assessment

Periodically, a lab test or quiz will be given which will assess all of the labs performed. Students will sometimes be permitted to use their laboratory notebooks for these tests, but may not use the lab handouts. Forgetting to bring your lab notebook on the day of the assessment does not excuse you from taking the test.

Lab notebooks will be checked at the beginning of each lab. At this time, notebooks will be checked for completion and thoroughness of the pre-lab requirement of the current lab. The post-lab requirement due date will vary for each lab. You will receive points for the pre-lab requirement.

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Metric Measurements LabCopy this table in your notebook. Work for all bolded items must be shown in your notebook.

Measurement(with unit) Convert to:

1 Your height (in) km

2 The mass of a #4 rubber stopper cg

3 The diameter of a 250 mL beaker µm

4 The volume of a chemistry textbook (cm3) (record 3 measurements)

mm3

5 The area of the seat of a student's desk (cm2) (record 2 measurements)

ft2

6 Your weight (lb) hg

7 The height of a lab bench Gm

8 The mass of a clay triangle mg

9 The circumference of your wrist (cm) ft

10 The mass of a pair of safety goggles dag

11 The volume of liquid in the 1 L Graduated Cylinder on the front bench dL

12 The length of your stirring rod nm

13 The width of your lab drawer Mm

14 The volume of an evaporating dish pts

15 The mass of your crucible tongs hg

16 The volume of 43 drops of water μL

17 The length of the teacher's lab desk yds

18 The area of the glass plate (cm2)(record 2 measurements) in2

19 The length of your foot (wearing shoe) nm

20 The mass of your Erlenmeyer flask oz.

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Specific Heat Investigation

Introduction: The specific heat of a substance is a physical property of that substance. This investigation will have you explore this physical property for both copper and lead.

Procedure:

1. Measure the 30. mL of deionized water and add to the Styrofoam cup. 2. Record the temperature of the water in the Styrofoam cup.3. Mass out approximately 30 g of copper metal. Record the exact mass of copper used and transfer it to a

small test tube. Secure a utility clamp around the top of the test tube. 4. Add enough tap water to a 400 mL beaker so that the water level in the beaker is higher than that of the

metal in the test tube when it is placed inside the beaker. 5. Secure the clamp to the ring stand. Heat the water in the beaker on a hot plate until it is boiling and let it

boil for 5 minutes with the test tube and metal resting in the water. Record the temperature of the boiling water. Let the thermometer cool for one minute.

6. Using the utility clamp as a handle, quickly pour the metal from the test tube into the deionized water in the Styrofoam cup.

7. Gently mix the metal in the water with the thermometer and accurately record the highest temperature reached by the mixture.

8. Drain the water, dry the metal and return it to the location designated by your teacher. 9. Repeat this process for the lead metal.

Analysis:1. INTERPRET the data. IDENTIFY any relationships that you notice when looking at the collected data.

Draw a conclusion statement that summarizes the relationship between the data.

Questions:

1. What is the purpose of leaving the metal in the boiling water bath for 5 minutes?2. What is the purpose of recording the temperature of the boiling water? (What does it tell us?)3. Why was there a change in temperature of the water? Explain the cause of the temperature change. 4. Predict what would happen to the temperature of the water in the Styrofoam cup if 50 grams of each

substance was used instead of 30g. If 10 grams of each metal were used? 5. Predict what would happen to the temperature of the water in the Styrofoam cup if 75 grams of water

was used with each metal instead of 30g. If 10 grams of water was used? 6. What kind of relationship exists between temperature changes and heat transfer? 7. What kind of relationship exists between mass and heat transfer? 8. If the same mass of each metal was used, why were the temperature changes in the water for each trial

different?9. What property of the metal would support/explain why the temperature differences in the water

occurred? 10. Develop a mathematical equation that you could use to represent the relationship determined throughout

this lab experience. You can use words or symbols in your equation to get your point across.

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Density of Solids

Procedure:

1. Determine the mass and volume (water displacement) of 5 different quantities of either copper, lead, chromium, silicon, iron or aluminum. Do not weigh the metal when it is wet.

Strive for a 1 mL or larger difference between all volume measurements.

2. Return the metal to the beaker in the front of the room so that it can be dried and reused.

Graph:

1. Prepare a mass vs. volume graph, using proper graphing techniques outlined below. Do not connect the plotted points. Draw a line of best fit.

2. Determine the slope of the line (show work). This is your experimental value for density. Include a unit.

Elements of a good graph: Constructed on graph paper with a ruler. Title that reflects the meaning of the graph. A title needs to explain the graph. Axes are labeled with the property being measured and the unit Each axis is numbered with equal intervals that begin at the origin with 0. The intervals are

chosen in a fashion that includes all of the data and maximizes the size of the graph. The axes do not need to be numbered with the same intervals.

Questions:

1. Determine the percent error for your experiment. Use the slope for your density! Accepted values in book and on periodic table.

% Error= Experimental−AcceptedAccepted

×100

2. List two sources of error for this experiment (be specific – do not include human error, or incorrect reading of the balance or graduated cylinder). Explain how the error affected the results of the lab.

3. Based on your graph, describe the precision of your experiment.

4. Describe the difference in appearance of a graph of (A) precise, accurate data and a graph of (B) precise, inaccurate data.

5. Describe the difference in appearance of a graph of (A) precise, accurate data and a graph of (B) imprecise, inaccurate data.

6. Using your experimental value for the density of your metal, determine the weight, in pounds, of a 0.856 ft3 block of the metal. Show all work.

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Law of Conservation of Matter

Introduction:

In part I of this lab, you will be reacting separate solutions of two compounds to produce two different compounds. One of these products will be insoluble in water and will therefore precipitate out of solution. The other product will remain dissolved. If the precipitate is filtered out of the solution and dried, its mass can be determined. If the remaining filtrate is heated to dryness, the other compound will be left as a residue and its mass can be determined. Knowing the masses of initial substances reacted and the masses of the substances produced, the law of conservation of matter can be observed. In part II, a different reaction will be performed, but the reactant and product masses will be compared as in part I.

Procedure:

Part I1. Weigh 2.12 g of strontium nitrate — Sr(NO3)2 — and place it in a small beaker. Remember to weigh the

paper first. Similarly, weigh 1.06 g of sodium carbonate − Na2CO3 − and place it into another small beaker. Add 10 mL of deionized water to each and stir until dissolved.

2. Combine the two solutions.3. Weigh a piece of filter paper. Set up a filtering apparatus using a long stem funnel, the folded filter

paper, and an Erlenmeyer flask. Gently swirl the beaker containing the products in order to mix up the precipitate and begin to slowly pour it into the filter. Do not allow the contents to rise higher than the filter paper in the funnel. Continue adding the product to the filter (while swirling the beaker) until the beaker is empty. Add a small amount of water to the beaker to rinse it and pour that into the filter as well.

4. After all of the liquid has passed through the filter, carefully remove the filter paper (use forceps) and lay it flat on a watch glass. Place the watch glass under the heat lamp in the fume hood.

5. Weigh a 250 mL beaker. Pour the filtrate into this beaker and heat it with a Bunsen burner (ring stand, etc.) to dryness.

6. Once dry, weigh the filter paper containing the precipitate and the beaker containing the residue.

Part II1. Add 20 mL of dilute hydrochloric acid – HCl – to an Erlenmeyer flask. Weigh the flask and contents.2. Weigh 1.00 g of calcium carbonate – CaCO3 – and add this to the Erlenmeyer flask.3. When the reaction is complete, weigh the flask and contents again.

Part I Calculations : (Show work and units) Total mass of reactants ____________

Mass of precipitate ____________

Mass of residue ____________

Total mass of products (precipitate and residue) ____________

Amount of mass gained or lost ____________

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Part II Calculations: (Show work and units)

Total mass before mixing ____________

Total Mass after Mixing ____________

Amount of mass gained or lost ____________

Questions:

1. State the Law of Conservation of Mass.

2. Clearly define the following terms:

a. filtrate

b. residue

c. precipitate

d. solution

3. Interpret the data from Part I of the lab and indicate if your results are consistent with the Law of Conservation of Mass (within a reasonable margin of error). Explain.

4. List some specific sources of error for part I of this experiment. Sources of error need to be specific from this lab. Generic responses such as “human error”, “incorrect measurements”, and “inaccurate balances” are not acceptable.

5. Interpret the data from Part II of the lab and indicate if your results are consistent with the Law of Conservation of Mass (within a reasonable margin of error). Explain.

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Physical and Chemical Changes

***Measurement tip: Most liquid measures in this experiment are 2 mL. To approximate this volume, measure 2 mL of water with a graduated cylinder and pour it into a test tube. Note the height of the water in the test tube. Fill test tubes to that height throughout the lab when a 2 mL is called for.Procedure:

1. Grind several crystals of copper(II) sulfate pentahydrate (CuSO4 ∙ 5H2O) with the mortar and pestle. Record observations. Transfer the powder into a test tube and heat it in a Bunsen burner. Note changes in the appearance of the solid and any changes at the mouth of the test tube. Allow the test tube to cool for several minutes and then add tap water one drop at a time until a noticeable change occurs. Disposal: add water and heat over Bunsen burner. Discard in drain with water.

2. Obtain 2 pieces of magnesium ribbon. Grip one piece of magnesium with crucible tongs and hold it in the flame until it ignites. Hold the burning Mg over an evaporating dish and do not look directly at it while it is burning. When it stops burning, allow the ashes to fall into the evaporating dish and observe. Disposal: metal trash can.

Add 2 mL of 3.0 M HCl (hydrochloric acid) to two clean test tubes and place them in a test tube rack. Add the other piece of magnesium to one of the test tubes and the ash from the burned magnesium to the other. Observe. Disposal: HCl can be disposed down the drain. Throw away any unreacted magnesium in the trash.

3. Add 2 mL of 1.0 M NaOH (sodium hydroxide) to one test tube and 2 mL of 1.0 M NH4Cl (ammonium chloride) to another. Using proper wafting techniques, observe the odor of each solution. Combine the contents of each test tube in a small beaker. Gently swirl the beaker and observe the odor. Disposal: discard in drain with water.

4. Pour 15 mL of tap water into a beaker. Add 1 scoop of copper (II) chloride (CuCl2) to the water. Stir to dissolve. Measure the temperature of the solution. Obtain a piece of aluminum foil and roll it up in a ball. Add the foil to the beaker and insert the thermometer. Record the highest temperature reached. Disposal: solids in metal trash can, liquid in drain with water.

5. Measure 1.0 g of solid sodium sulfate (Na2SO4) and put it in a beaker. Add 50 mL of deionized water. Stir until dissolved. Add 2 mL of this solution to a test tube and 20 mL of it to an evaporating dish. The rest can be discarded. Place the evaporating dish on a ring stand with a wire gauze and heat the evaporating dish to dryness. While it is heating, add 2 mL of 0.10 M Ba(NO3)2 (barium nitrate) to a new test tube and observe. Pour the test tubes containing the barium nitrate and the sodium sulfate into a beaker and observe. Disposal: barium waste beaker in classroom.

6. Add 2 mL of 0.10 M HCl to one test tube and 2 mL of 0.10 M NaOH (sodium hydroxide) to another. Measure the pH of each solution by dipping a clean stirring rod into the solution and touching a piece of pH paper with the stirring rod. Compare the color of the paper to the color chart to obtain the pH value. After the pH has been measured for each solution, combine the solutions in a beaker. Gently swirl the beaker and measure the pH of the resulting solution. Disposal: discard in drain with water.

7. Take a small scoop of sulfur and a small scoop of iron filings and mix them thoroughly in a small beaker. Carefully pour the mixture into a small, disposable test tube. Run a magnet along the outside of the test tube and record observations. In the fume hood, heat the test tube in Bunsen burner for several minutes until the mixture glows. Allow it to cool for several minutes. Run a magnet along the outside of the test tube again. Observe. Disposal: broken glass container.

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Analysis:

Determine whether each procedure step was a physical or chemical change and explain why you made this determination. (Hint: Most procedure steps will have more than one change.)

Questions:1. List three pieces of evidence from this experiment that can be used to determine if a physical change has

taken place.

2. List three pieces of evidence from this experiment that can be used to determine if a chemical change has taken place.

3. Imagine that two people are sitting around a campfire heating marshmallows. How can one person cause a physical change to occur with the marshmallow while the other person causes a chemical change?

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Determining the Specific Heat of Iron

1. Determine the mass of a piece of iron. Use nichrome wire to attach the iron to your ring stand using a utility clamp, as shown by your teacher.

2. Measure and add 100 mL of deionized water to a Styrofoam cup. Density of water = 1.00g/mL. 3. Record the temperature of the water.4. Fill a 400 mL beaker two-thirds full of tap water, and bring it to a boil on the ring-stand set-up. Once the

water is boiling, record the temperature of the boiling water.5. Submerge the piece of iron in the boiling water for 5 minutes.6. Turn off the flame and carefully lift the iron from the boiling water and quickly submerge it in the water in

the Styrofoam cup. Record the highest temperature reached by the water.7. Remove the iron from the water. Dry the iron and leave it set-up for the next portion of the lab.8. Use your collected data to determine the specific heat of iron.

Calculations: 1. Show calculations for the determination of the specific heat of iron. Be sure to use units.

2. The accepted value for the specific heat of iron is 0.449 J/g •°C. Determine the % error for your results.

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3. Temperature of a Bunsen Burner Flame

Procedure:1. Fill the cup half way with water. Measure the volume of water using a graduated cylinder and record

the total volume of water in the cup. Record the mass of water (density = 1.00 g/mL).2. Measure and record the temperature of the water.3. Turn on the Bunsen Burner and position it so that the metal is in the hottest part of the flame (the inner

blue cone).4. Allow the metal to heat in the flame for 5 minutes.5. Turn off and remove the Bunsen Burner.6. Slowly lift the cup of water so that the metal is submerged. Be prepared for a loud sizzling noise. Do

not be startled by it.***DO NOT ALLOW THE METAL TO TOUCH THE SIDE OF THE CUP***

7. Allow the metal to remain in the water for 1 minute while gently stirring. After the 1 minute, record the temperature.

Analysis: Using the data and your experimental value for the specific heat of iron, determine the temperature of the Bunsen burner flame. Show all work.

Assume: The initial temperature of the iron is the same temperature as the flameHeat lost by metal = Heat gained by waterSpecific Heat of water = 4.184 J/goC

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Law of Definite Composition

Introduction:

Elements are a kind of matter that cannot be decomposed by ordinary chemical means. Compounds are chemical combinations of elements. The law of definite composition (a.k.a. law of definite proportions) states that the elements forming a compound always combine in the same proportion by mass. Water, H2O, is always a chemical combination of hydrogen and oxygen in a 1:8 ratio by mass (1 g of hydrogen for every 8 g of oxygen). If a mixture of hydrogen and oxygen were reacted in some other mass ratio, for example 1:2, water would still be formed but some hydrogen would remain unreacted.

In this experiment, you will examine the reaction between magnesium metal and oxygen gas. When magnesium burns, it chemically combines with oxygen to form magnesium oxide. You will determine the mass ratio of magnesium to oxygen.

Procedure:

1. Coordinate with another lab group in the class. Each of the two groups is to obtain a piece of magnesium (15 cm – 25 cm) of different lengths, complete the procedure, and exchange data with the other group.

2. Determine the mass of an empty crucible and cover. Coil (spiral) the magnesium loosely, add it to crucible and reweigh it with its cover.

3. Set up a ring stand with an iron ring, clay triangle and Bunsen Burner. Support the covered crucible in the clay triangle and begin to heat it gently. Periodically, lift the lid slightly to allow oxygen to enter and to determine if the magnesium is reacting (it will glow strongly and produce smoke). It is important to minimize the amount of smoke that escapes.

4. Once the magnesium is reacting, continue heating the crucible and slightly lifting the lid until no more smoke is present. At that point, rest the lid on the crucible and triangle so that it is only partly on and heat the crucible intensely for 5 minutes. Allow the crucible to cool for several minutes.

5. In addition to magnesium oxide forming in the crucible, magnesium nitride may also form. To remove the nitride, add ten drops of distilled water (this will convert the magnesium nitride to magnesium oxide and will release ammonia gas – see if you can smell the ammonia being released by using proper wafting techniques). Heat the crucible intensely again for five minutes with the lid off.

6. Allow the crucible to cool for several minutes and determine the mass of the crucible, cover and product. Consider this mass as the mass after the first heating.

7. Reheat the crucible for another 3 minutes without the lid. Allow it to cool and reweigh it for the second time. It is necessary to have two consecutive masses within 0.03 g of one another. If the second mass is not within 0.03 g of the first, then a third heating and massing will be necessary. Use the final mass for all calculations.

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Calculations:Trial 1 Trial 2

Mass of magnesium reacted

Mass of magnesium oxide produced

Mass of oxygen reacted

Ratio of the mass of magnesium to the mass of oxygen

Percent Error (accepted ratio = 1.52)

Questions:

1. In the procedure, you were asked to reheat the crucible repeatedly until the last two masses agreed within 0.03 g. What is the purpose of this reheating?

2. If you were to combine 80.0 g of oxygen with some hydrogen, how much hydrogen would you need to completely use up all the oxygen? The hydrogen to oxygen ratio is 1:8 by mass. Show work.

3. Suppose a compound of sodium and chlorine is formed in the ratio of 1.54g of chlorine for each gram of sodium. How much sodium would you need to completely react 45.0 g of chlorine?

4. How would your results for this experiment be affected if all of the magnesium did not react? (Be sure to explain the effect on the final ratio)

5. Explain the significance of analyzing data obtained from the combustion of 2 pieces of magnesium of different lengths.

6. Suppose you tried to combine 42.0 g of magnesium with 45.0 g of oxygen.

a. Which of these two substances would have been left over after the reaction and how much? (Show work)

b. How much magnesium oxide would be formed? (show work)

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% Error= Experimental−AcceptedAccepted

×100


Thickness of Aluminum Foil

Purpose: To determine how many aluminum atoms make up the thickness of a piece of aluminum foil?

Imagine that there are aluminum atoms stacked on top of each other. How many aluminum atoms would be required to make up the thickness of a piece of aluminum foil?

Materials:

7 – 10 pieces (shots) of aluminum metal (You MUST use all of them) Rectangular piece of aluminum foil (No bigger than 10 cm x 12 cm) 10 mL graduated cylinder Balance Ruler Water

Given Information:

D = m/V V = l x w x h radius of Al atom = 1.43 Å

Required work:

Prediction Data/Results Calculations Conclusion w/source of error and how the error affects the results.

A Qualitative Analysis of Some Common Household Chemicals

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ObjectivesTo utilize a qualitative analysis scheme using simple chemical and physical tests in order to identify ten

white solids, which may be found in the typical home.

Unknown CompoundsCompound Household Source Compound Household Source

Calcium sulfate Plaster of Paris Calcium carbonate White chalk

Fructose Fruit sugar Cornstarch Cornstarch

Sodium chloride Table salt Magnesium sulfate Epsolm salts

Sodium carbonate Washing soda Sodium bicarbonate Baking soda

Sucrose Table sugar Sodium hydroxide Drain opener

Test ReagentsReagent Test Reagent Test

Copper sulfate solution

Reducing sugar test Vinegar Carbonate and bicarbonate identification

Iodine Starch Identification Water Solubility

Phenolphthalein Basic solution identification

Test Proceduresa. Solubility in water Place a pea-sized amount of the material to be tested on the end of a scoopula and place it

in a small clean dry test tube and add about 5 mL of deionized water. Along with some agitation, observe the solid for 2-3 minutes to determine if it dissolves.

b. Iodine test Place a pea-sized sample of the material in a test tube and add two drops of iodine reagent and 5 mL of deionizedwater. The deep blue color of the starch-I2 complex indicates that cornstarch is present.

c. Vinegar test Place a pea-sized sample of the unknown into a clean dry test tube and add about 1 mL of vinegar (dilute acetic acid) and note if bubbles are produced. Evolution of CO2 gas, after the addition of vinegar, positively identifies a carbonate or bicarbonate compound.

d. Alkalinity test (Phenolphthalein test)

Dissolve a pea-sized sample of the solid in 5 mL of deionized water and add 2 drops of phenolphthalein indicator solution. The appearance of a pink color indicates the presence of base.

e. Sodium hydroxide test Dissolve a pea-sized sample of the solid in 5 mL of deionized water and then add 5 drops of dilute NaOH. The appearance of a whitish-tan precipitate indicates the presence of MgSO4.

f. Reducing sugars test (Copper sulfate test)

Dissolve a pea-sized sample of the solid in 5 mL of deionized water (or use the sample from the NaOH test, if the test was negative for MgSO4.) Add 15 drops of the copper sulfate solution to the test tube. Place the test tube in a beaker of warm water for about 2 minutes. The presence of an orangish precipitate indicates the presence of a reducing sugar, such as fructose or glucose.

g. Hot water solubilty Add a pea-sized sample of the solid to a small dry test tube and then add 3 mL of warm water to the test tube and agitate. The sucrose will readily dissolve while the sodium chloride will not.

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Qualitative Analysis Scheme

NaCl, NaHCO3, CaSO4, Sucrose, CaCO3, NaOH, Cornstarch, Fructose, MgSO4, Na2CO3

WaterInsoluble Soluble

CaSO4, CaCO3, Cornstarch NaCl, NaHCO3, Sucrose, NaOH, Fructose, MgSO4, Na2CO3

Iodine

Cornstarch CaSO4, CaCO3

Deep Blue Yellowish -Brown

VinegarBubbles

CaCO3 CaSO4

PhenolphthaleinDeep Pink

NaOH, Na2CO3 NaCl, Sucrose, Fructose, MgSO4, NaHCO3

Vinegar

Bubbles

Na2CO3 NaOH

Use New Sample

Sodium Hydroxide (aq)

WhitePrecipitate

MgSO4Sucrose, Fructose, NaHCO3, NaCl

Copper SulfateOrangish Precipitate

Fructose Sucrose, NaHCO3, NaCl

Vinegar Bubbles

NaHCO3Sucrose, NaCl

Hot Water

Sucrose NaCl

Very Soluble (Dissolves Readily) Less Soluble (Dissolves Partially)

Name(s)_____________________________________ Date Performed ________ Date Due _______

Report Sheet for Household Chemicals Qualitative Lab

Test Results

** Indicate test results using either positive (+) or negative (−), or write out the actual results (bubbling, no bubbling, blue color, no white precipitate, etc.)

Unknown # Water Iodine Vinegar Phenolphthalein Vinegar Sodium

HydroxideCopper Sulfate Vinegar Hot Water Identity

A

B

C

D

E

G

H

I

J

K

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Solutions Lab

1. Carefully weigh out 2.2 grams of anhydrous sodium sulfate and add it to a large test tube. Using a graduated cylinder, measure and add 10.0 mL of distilled water to the test tube. Stopper the test tube and shake.

a. Describe the contents of the test tube.

b. Is the solution saturated, unsaturated or supersaturated?

c. How do you know?

2. Remove the stopper from the test tube. Clamp the test tube and gently heat it in a Bunsen burner. While heating, stir the solution frequently with a stirring rod until all of the solute is dissolved. Add a very small amount of solid solute to the test tube and stir.

a. Describe the contents of the test tube:

b. What happened to the added solute?

c. Is the solution saturated, unsaturated or supersaturated?

d. How do you know?

3. Place the test tube in a beaker of ice water for five minutes. Do not disturb the solution during this process. Gently remove the test tube and place it in a test tube rack. Add a very small amount of solid solute to the test tube. Do not stir or shake the tube. Observe the test tube for several minutes.

a. Describe the contents of the test tube before the extra solute was added.

b. What happened when the extra solute was added?

c. Describe the contents of the test tube after the extra solute was added.

d. Was the solution before adding the crystal saturated, unsaturated or supersaturated?

e. How do you know?

f. Was the solution after adding the crystal saturated, unsaturated or supersaturated?

g. How do you know?

4. Explain one simple test that will determine whether a solution is saturate, unsaturated or supersaturated. Explain how to interpret the test result.

20


Absolute Zero

Procedure:

1) Wear goggles and apron at all times.

2) Measure the total volume of the test tube by first placing the stopper in the top of the flask and drawing a line indicating the bottom of the stopper with your grease pencil. Fill the test tube with water up to the line and pour the water into a graduated cylinder to measure it.

3) Take the 500 mL beaker and fill it with approximately ¾ full with water. Place a one-hole stopper fitted with glass tubing in the top of the test tube, and place the test tube in the beaker of water. Make sure there is space between the test tube and sides of the beaker to allow room for the steam to escape. Heat the water to boiling. Continue heating for 3-5 minutes. (see figure A)

4) Measure the temperature of the boiling water and assume this temperature to be the same as the temperature of the gas in the test tube. Remove the test tube from the beaker. Protect your hand with a towel while placing your finger firmly over the end of the glass tubing. CAUTION: TEST TUBE IS HOT! Submerge the test tube upside down in the bin of water in the sink. (Be careful to not allow air to enter the test tube while transferring.)

5) Remove your finger from the glass tubing and hold the test tube under the water (with open end down) until the test tube has cooled and the water ceases to enter. Raise the test tube until the water level outside the test tube is equal to the water level inside the test tube. The pressure is now equal to the atmospheric pressure. (see figure B)

6) Place your finger over the glass tubing while the outside levels are equal. Remove the test tube from the water and place it upright in test tube holder. Measure the volume of the water in the test tube by pouring the water in a graduated cylinder.

7) Measure the temperature of the water bath and assume this to be the gas temperature.

8) Repeat the procedure for Trial 2 and 3 using different water temperatures. (The bins in the other two sinks.)

21


Analysis:

1) Determine the Gas Volume and Temperature in K for the initial reading and all trials.

2) Prepare a graph of Gas Volume (y) vs. Gas Temp in Kelvin (x)

3) Draw a line of best fit and extrapolate the graph to determine the x-intercept (experimental value of absolute zero)

4) Determine the percent error.

5) Convert 37oC to Kelvin.

6) Convert 398 K to oC.

7) What is the volume of a gas at 295 K if the same gas has a volume of 42.9 mL at 357 K?

8) A gas has a volume of 50.8 mL at 25oC. What is the volume of the gas at 50oC.a. Calculate first using Celsius temperatures

b. Calculate again using Kelvin temperatures

c. Which is correct? Why?

22


Precipitation Reactions: Formula Writing

Procedure1. Obtain 6 disposable pipettes and label them 1 through 6.2. Place each pipette upside down in a beaker.3. Fill each pipette with the solution that corresponds to its number and keep the pipette in its beaker

upside down. Do not empty the contents of the pipette into the beaker

1. barium chloride2. magnesium nitrate3. sodium chromate4. aluminum sulfate5. potassium chromate6. silver nitrate

Combine each solution with every other solution by combining 1 drop of each on a transparency. (Combine solution 1 with each of solutions 2 through 6. After that set is complete, combine solution 2 with each of the solutions 3 through 6, etc.) Record all combinations that produce a precipitate.

Data: Record all combinations that produced a precipitate.

Analysis: For each precipitate reaction, write the formula and name for each reactant on the space provided. Write the names and formulas for the two compounds produced. (This can be determined by switching the metals in the reactants). Consult a table of solubility rules to determine which product is the precipitate.

Note: There is space provided for 10 precipitates. There may be less.

Example: A yellow precipitate is produced when solutions of lead(II) nitrate and sodium iodide are mixed.

The two products (by swapping metals) would be sodium nitrate and lead(II) iodide. According to the solubility rules, sodium nitrate is soluble. Therefore, lead(II) iodide must be the precipitate.

23


Reacting Chemicals Chemicals producedformula name formula name PPT?

Example

Pb(NO3)2 lead(II) nitrate NaNO3 sodium nitrate no

NaI sodium iodide PbI2 lead(II) iodide yes

1

2

3

4

5

6

7

8

9

10

24


Heat of Fusion of Ice

Procedure: 1. Warm about 125 mL of water to about 50-60oC.2. Measure 100. mL of this warm water into a Styrofoam cup. Record the volume and temperature.3. Obtain several ice cubes (6-7 pieces). Shake excess water from them and dry them with a paper

towel. Place the ice in the warm water and stir the mixture with a stir rod until the temperature is about 0oC. Add more ice if needed to cool the water. Record the lowest temperature reached (Tf).

4. Remove the unmelted ice using crucible tongs or forceps. Be sure to drain back as much water as possible into the cup when you remove the ice.

5. Measure the volume of water remaining in the calorimeter.

Make your own data table in your lab notebook!

Calculations:

Mass of water cooled Mass of ice melted

ΔT of water Moles of ice melted

Heat lost (q) by water

Heat gained by ice (q)

Heat gained per gram of ice

Heat gained per mole of ice

Heat of fusion of ice in KJ/mol

Actual Heat of Fusion: 6.008 kJ/mol

Percent Error: ________________

25


Qualitative Analysis 1: Relative SolubilitiesThe elements of the second column of the periodic table all form ions with a +2 charge. The

chemistry of these elements is so similar that they are difficult to separate. Many of their compounds are

only slightly soluble; however, it is possible – by choosing the proper anion – to find differences in

solubility, which will permit you to differentiate between the cations of these metals.

In this experiment, you will study the effect of adding reagents containing specific anions to solutions

containing the cations of the metals in the second column. After a systematic study of the relative

solubilities of their carbonates, chromates, sulfates, oxalates, and hydroxides you should be able to make a

qualitative analysis of an unknown solution containing one or more of these cations.

Materials: Solutions Cations Used0.1 M Ba(NO3)2 Ba+2 barium0.1 M Sr(NO3)2 Sr+2 strontium0.1 M Ca(NO3)2 Ca+2 calcium0.1 M Mg(NO3)2 Mg+2 magnesiumReagents Anions Used2 M (NH4)2CO3 CO3

-2 carbonate0.5 M K2CrO4 CrO4

-2 chromate0.2 M (NH4)2C2O4 C2O4

-2 oxalate1 M (NH4)2SO4 SO4

-2 sulfate9 M NH3 (aq) OH-1 hydroxide

Data: Add 1 drop of each cation and each anion on transparency as shown on the table below.(NH4)2CO3

CO3 -2

K2CrO4

CrO4-2

(NH4)2C2O4

C2O4 -2(NH4)2SO4

SO4-2

NH3

OH-1

Ba(NO3)2

Ba+2

Sr(NO3)2

Sr+2

Ca(NO3)2

Ca+2

Mg(NO3)2

Mg+2

26


Analysis of Data:

1. a. Which carbonate of the above positive metal cations has the greatest solubility? _____________

b. Which cations have similar solubilities?_____________________________________

c. Describe how you could separate one of these cations from the other three.

2. a. Which chromate of the metals is the least soluble? _________________________

b. How can this difference in solubility be used in an analytical separation of a solution containing both Sr+2 and Ba+2?

3. With which of the anions does the magnesium ion have the lowest solubility? _________________

4. Which oxalate of these metals is the most soluble? ___________________________

Flow Chart of Data for Knowns

Mg +2 , Ca +2 , Ba +2 , Sr +2

↓add CrO4-2

ppt: soluble:____________________________

↓add SO4-2

ppt: soluble:____________________

↓add CO3-2 or C2O4

-2

ppt: soluble:__________________

↓add NH3 (OH-)

ppt: ____soluble:________

27


Unknowns Procedure:

1. Obtain your unknown set # from your teacher. 2. Test each of your unknowns with the anions listed in the flow chart below and record your results in

the appropriate spaces3. On transparency, add 1 drop of unknown with CrO4

-2 and 1 drop of unknown with NH3.4. If precipitate forms with CrO4

-2, add 20 drops of unknown with 20 drops of CrO4-2. This is to ensure

that all the barium is removed from the unknown solution. Make sure that a slight yellow color remains in solution. This indicates that chromate is in excess and all barium is removed.

5. Centrifuge test tube to separate solid from solution. 6. If no precipitate forms on the transparency, move to the next step. Add 20 drops of unknown with 20

drops of SO4-2.

ANY time a precipitate forms, centrifuge test tube for at least 10 seconds. Remove liquid with a pipette. The liquid must be clear. Continue to centrifuge until it is clear. Once clear solution is removed and placed in a new test tube, add 20 drops of the next anion to the solution.

If no precipitate forms, move on to the next step adding 20 drops of the next anion.

If a precipitate formed with NH3, it is unnecessary to do the last step of adding 20 drops of NH3. If no precipitate formed, double check work at the end by adding 20 drops of NH3 to see if a precipitate forms.

7. Fill in the ions present in both of your unknowns on the slip provided to you by your instructor and hand in by the end of the period.

The flow chart lists all the possible metal ions that may be present in your unknown at the top. When you test your unknown with the first anion, CrO4

-2, a reaction will occur. Record whether or not a precipitate was formed as well as a description of it. Then refer to your data table above that contains your knowns and compare the results. For example, if there is a match with the reaction between Mg+2 and CrO4

-2, then Mg+2 must be present in your unknown. Complete the analysis for both of your unknown solutions.

28


SCHEME of ANALYSIS (to be used for analysis of unknowns) = FLOW CHART

Mg +2 , Ca +2 , Ba +2 , Sr +2

↓add CrO4-2

ppt: soluble:____________________________

↓add SO4-2

ppt: soluble:____________________


-2

ppt: soluble:__________________

↓add NH3 (OH-)


Mg +2 , Ca +2 , Ba +2 , Sr +2

↓add CrO4-2

ppt: soluble:____________________________

↓add SO4-2

ppt: soluble:____________________


-2

ppt: soluble:__________________

↓add NH3 (OH-)


29


The Mole Lab

Procedure:

1. Determine the mass of a packet of sugar.2. Determine the mass of a sip of water. 3. Determine the mass of a nickel.4. Determine the mass of chalk used to write your signature. Write your signature 3 times on the board.

Data and Calculations: You MUST show ALL work to get full credit!

1. Measured mass of sugar (C12H22O11): ______________________

a. Determine the molar mass of sugar: ____________

b. Calculate the number of moles of sugar: ____________

c. Calculate the number of and kind of particles of sugar: ____________

d. Calculate the total number of hydrogen atoms present: ____________

2. Measured mass of water in a small cup: ________________________

a. Determine the molar mass of water: ____________

b. Calculate the number of moles of water: ____________

c. Calculate the number of and kind of particles of water: ____________

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3. Measured mass of the nickel: ___________________

Assume a nickel to be 25.0% nickel and 75.0% copper.a. Calculate the mass of nickel in the coin. ____________

b. Determine the molar mass of nickel. ____________

c. Calculate the number of moles of nickel present ____________

d. Calculate the number of and kind of particles of nickel. ____________

e. Calculate the mass of copper in the coin. ____________

f. Determine the molar mass of copper. ____________

g. Calculate the number of moles of copper present ____________

h. Calculate the number of particles of copper. Identify the particle. ____________

4. Measured mass of chalk used in your signature: _________________________Chalk is calcium carbonate

a. Formula of calcium carbonate: ____________

b. Determine the molar mass of the chalk ____________

c. Calculate the number of moles of chalk used. ____________

d. Calculate the number of and kind of particles of chalk used ____________

e. Calculate the total number of oxygen atoms present. ____________

31


32


Hydrates

Introduction:Many ionic compounds (salts) have one or more water molecules loosely bonded to it which can be easily removed by heating to produce the anhydrous salt. For example, the ionic compound copper(II) chloride is hydrated with two water molecules and is properly named copper(II) chloride dihydrate. The chemical formula is CuCl2∙2H2O. Mathematically, one can conclude that every mole of copper(II) chloride dihydrate contains one mole of anhydrous copper(II) chloride and two moles of water.

In this lab, two hydrated salts will be heated to drive off the water molecules to produce the anhydrous salt. Based on the mass differential, you can determine the mass and moles of water present in the compound. From these data, the number of water molecules in the formula is to be determined.

Hydrated Salts: MgSO4∙×H2O CuSO4∙×H2O BaCl2 ∙×H2O ZnSO4 ∙×H2OMnSO4∙×H2O Na2CO3∙×H2O CaSO4 ∙×H2O

Procedure:

1. Using a ring stand, iron ring, clay triangle and Bunsen burner, heat an empty crucible (no lid) intensely for two minutes to burn off any impurities on the crucible that may ultimately affect the mass. For the remainder of the experiment, the crucible is only to be handled with crucible tongs. Allow the crucible to cool for a few minutes and determine its mass.

2. Add one of the hydrated salts to the crucible until it is approximately one-third full and determine the combined mass.

3. Heat the crucible intensely for 10 minutes.4. Allow it to cool for a few minutes and then determine the mass.5. Heat the crucible again for about 2 minutes. Allow it to cool and remass. If the mass is not within

0.03 grams of the previous mass, it must be heated again until there are two consecutive masses within 0.03 grams. Remember to use the final mass in all calculations.

6. Repeat the above procedure for the other hydrated salt.

33


Calculations: Show all work and be attentive to significant figures.Hydrate 1 Hydrate:2

Mass of hydrated salt

Mass of anhydrous salt

Moles of anhydrous salt

Mass of water

Moles of water

Moles of water for every 1 mol of anhydrous salt

Chemical Formula of hydrate

Actual number of moles of water in compound

Percent error

Questions: Show work for all calculations.

1. Suppose one of the hydrates in this experiment was not heated long enough. What effect would that have on the determined chemical formula? Explain.

2. Calculate the percent water by mass for magnesium nitrate hexahydrate.

3. Calculate the mass of water in 2.89 g of sodium sulfate decahydrate.

4. Calculate the total number of oxygen atoms in 15.99 g of calcium nitrate tetrahydrate.

5. A sample of a hydrated salt is analyzed and is determined to be composed of 3.097 g of iron, 5.910 g of chlorine and 5.993 g of water. Determine the chemical formula for this hydrate.

34


35


Determining the Value of R Procedure:

1. Obtain a butane lighter and determine the mass.2. Fill a pneumatic trough and an Erlenmeyer flask with very warm water. Be sure that the flask is

completely filled with water. Place a glass plate over the mouth of the flask and carefully invert the flask into the trough. Place a thermometer in the trough, but do not yet measure the temperature. Do not submerge entire thermometer.

3. While holding the lighter in the water under the mouth of the flask, depress the gas release button. You will observe the flask filling with butane as it displaces the water. You must collect enough butane so that the water level inside the flask (while touching the bottom of the trough) is at or below the water level in the trough.

4. Shake off any water from the lighter and dry it thoroughly with a paper towel. Allow it to sit for a few minutes to ensure that it is dry and then reweigh it.

5. Equilibrate the pressure in the flask with the atmosphere. While holding the flask at this position, slide the glass plate under the mouth and quickly remove the flask from the trough turning it right side up without losing any water. Keep the glass plate over the mouth and carry the flask to the fume hood to release the gas.

6. Measure and record the water temperature, barometric pressure, volume of water remaining in the flask and the volume of water required to completely fill the flask. The formula for butane is C4H10.

Results: (work must be shown for bold items)

Volume of gas collected

Mass of butane (C4H10) in flask

Moles of Butane

Vapor Pressure of water

Partial pressure of butane

Experimental value of R

Actual value of R

Percent Error

Questions:

1. Calculate the volume that your butane sample would occupy at STP.

36


2. Assuming the same temperature, pressure and R value determined in this experiment, what volume would the gas have occupied had it been methane (CH4) instead of butane?

Single and Double Replacement Reactions

Single Replacement Procedure:

1) Clean and dry a spot plate.

2) Place 4 pieces of each metal (Cu, Mg, and Fe) in the spot plate. Place 5 drops of each solution (HCl, CuCl2, MgCl2, FeCl3) on the metals. Note if a reaction occurs. Dispose of the chemicals according to your teacher’s instructions. Thoroughly clean the spot plate and use it for the double replacement reactions.

Double Replacement Procedure:

1) React each solution labeled Reactant 1 with each solution in the Reactant 2 column.

Reactant 1 Reactant 2 AgNO3 Na3PO4

Cu(NO3)2 Na2SO4

Fe(NO3)3 NaOH

NaCl

2) Mix 2 drops of each solution in a clean spot plate. Note if a precipitate forms.

Analysis: Single Replacement

1. Write a balanced chemical equation for each reaction that occurred.

2. Prepare an activity series of the three metals tested by ranking them from most active to least active.

3. Based on your observations of reactions between the metals and hydrochloric acid, where would hydrogen fit in your activity series?

4. The Statue of Liberty is made of copper. Use your investigation results to explain why copper is a better material for a statue than magnesium or iron.

5. Gold does not react with any of the solutions used in this investigation. What does this tell you about gold’s chemical activity.

6. How does the chemical activity of gold account for its use in jewelry?

37


7. Lead is less active than zinc but more active than copper. Predict the results if lead metal is put into separate solutions of zinc nitrate and copper (II) nitrate.

Analysis: Double Replacement

1. Write a balanced chemical equation for each reaction that occurred.

2. Refer to a list of solubility rules and indicate if the following types of compounds are typically soluble or insoluble in water.

a. sodium compounds:______________ b. nitrates_______________

3. In each of the equations written in question #1, underline the formula for the product that was the precipitate formed.

4. In each of the following, solutions of the two indicated compounds are mixed. Determine if a precipitate will form. Write out a balanced chemical equation indicating the precipitate in the reaction.

a. tin (II) nitrate and sodium hydroxide

b. sodium nitrate and potassium carbonate

c. sodium bicarbonate and sodium chromate

d. silver acetate and calcium chloride

38


Predicting Products LabPre-lab Discussion: (this must be included in your lab notebook)

1. What constitutes a positive test for each of the following gases?

a. oxygen (O2):

b. hydrogen (H2):

c. water vapor (H2O):

d. ammonia (NH3):

e. carbon dioxide (CO2)

and/or

2. What is the proper way to smell a substance in the lab? _____________________________________

3. What is the role of a catalyst in a reaction? How can you tell if when a substance serves as a catalyst?

__________________________________________________________________________________

Procedure:

Read the procedure for each reaction in its entirety before doing it so that you have the necessary materials to complete the procedure. Wear goggles and an apron throughout the entire lab. Be sure to tie back long hair. Write detailed observations (before, during and after the reaction) in your data table. Follow disposal instructions.

Reaction 1: Cut a 3 cm piece of magnesium ribbon. Clamp the magnesium with a pair of crucible tongs. Ignite the magnesium in a Bunsen burner flame. Do not look directly at burning Mg. After it burns, collect the ashes on a watch glass. Disposal: discard ashes in trash can after it has cooled down.

Reaction 2: Obtain a piece of magnesium. Add 5-10 mL of hydrochloric acid to a test tube and place the test tube in a rack. Add the magnesium to the acid. Using a test tube clamp, invert a second test tube (as shown in the figure below) over the mouth of the reaction test tube and collect the gas being produced. Keep the test tube inverted and test the collected gas by inserting a flaming splint. Disposal: after all of the Mg has reacted completely with the HCl, the solution can go down the sink with lots of water.

39

Stopper in large test tube with the

CuCO3 Rubber tubing placed into the limewater


Reaction 3: Mass a scoop of copper powder in a crucible. Place crucible in a clay triangle on ring stand and heat over a Bunsen burner. Heat until you see a noticeable change throughout. Mass the copper once it cools. Disposal: after the copper cools, discard in the trash can.

Reaction 4: Obtain one scoop of ammonium carbonate and place it into a small, dry test tube. Clamp the test tube and heat it in a Bunsen burner – use proper technique. While the test tube is heating, touch a piece of cobalt chloride paper to the mouth of the test tube and remove it. Smell the test tube using the proper wafting technique. Hold a flaming splint in the test tube. Record the results of each test. Disposal: any solid remaining in test tube, discard in trash can.

Reaction 5: Measure 10 mL of hydrogen peroxide and add to a test tube. Add a very small quantity (tip of spatula) of manganese dioxide, MnO2, (catalyst) to the test tube. Place a glowing splint inside the mouth of the test tube. Hold a piece of cobalt chloride paper to the mouth of the test tube. Disposal: discard solution in sink, solids go in the trash can.

Reaction 6: Add 2 drops of potassium iodide and 2 drops of lead (II) nitrate to a watch glass. Record the results. Disposal: wipe the watch glass with a paper towel and discard the paper towel in trash can. Do not put it into the sink. Wash hands well with soap and water.

Reaction 7: Place two scoops of copper (II) carbonate in a large test tube. Insert a stopper with a glass bend in the test tube. Clamp the test tube to a ring stand on an angle so that the flame will touch the bottom of the test tube only. Fill a small test tube approximately half way with limewater. Position this test tube so that the end of the glass bend is in the test tube and is submerged in the limewater. Light the Bunsen burner and heat the solid in the large test tube. Observe any changes in the limewater and the solid. Disposal: discard any solid in the trash, the limewater solution may be put down the sink.

Please clean your lab area and lab equipment! Wash your hands!!!

40


Questions:

1. Write a balanced equation for every reaction using the test results. Include states in your equations. Also, indicate the reaction type for each reaction.

2. Write complete, balanced equations for each of the following:

a.When potassium bromate is heated, it decomposes into potassium bromide and a gas that reignites a glowing splint.

Reaction type:

b. Sodium metal reacts violently with water to produce sodium hydroxide and a gas that pops in the presence of a flame.

Reaction type:

c.When calcium hydroxide is heated, it makes calcium oxide and a substance that will turn cobalt chloride paper pink.

Reaction type:

d. When CH4 is burned in the presence of oxygen. It produces a substance that will extinguish a flaming splint and a substance that turns cobalt chloride paper pink.

Reaction type:

41


Qualitative Analysis 2: Ag + , Hg 22+ , and Pb 2+

Background Information:

Most common metal ions form soluble chlorides except Ag+, Hg22+, and Pb2+. Because of this it is

possible to separate these ions from other cations as chloride precipitates. Identification can then be made on the basis of distinguishing reactions of each chloride. The mercury (I) ion is a bit unusual in that is occurs in pairs: hence Hg2

2+ rather than Hg+.

In the first part of this experiment you will become familiar with a few reactions used to identify the silver, mercurous, and lead ions in aqueous solution. From these observations you should be able to devise a method by which you can analyze an unknown solution and determine the presence or absence of Ag+, Hg2

2+, and Pb2+.

Procedure: (20 drops are approximately 1 mL)

1. Prepare precipitates of AgCl, Hg2Cl2, and PbCl2 in separate, labeled test tubes by adding about 5 drops of 6 M hydrochloric acid, HCl, to about 1 mL of each of the test solutions, AgNO3, Hg2(NO3)2, and Pb(NO3)2. Make a record of your observations for each test.

2. Allow the chloride precipitates to settle to the bottom of the test tube. Centrifuge. Decant and discard the solution. Add about 2 mL of distilled water to each precipitate. Stir/shake the tests tubes to allow the precipitate to dissolve (not all of the precipitate will dissolve).

3. Centrifuge. Use disposable pipets to remove about 5 drops of the clear solution from each solution and transfer the drops to clean test tubes. Add about 5 drops of 0.1 M potassium chromate solution, K2CrO4, to each of the 3 test tubes. Determine and record which of the cations forms a precipitate with the chromate ion. (1 of the 3 will be different)

4. Decant and discard the solutions from the test tubes in step number 2. Save the precipitate for the next step.

5. To test the solubility of the chloride precipitates in aqueous ammonia, add about 3 mL of 6M ammonia solution, NH3 (aq), to each of the precipitates. (1 of the 3 will be different)

6. Shake the test tubes to dissolve as much of the solid chloride as possible. For each, decant about 1 mL of clear solution into a clean test tube. Add about 2-3 mL of 6 M nitric acid, HNO3, to each tube of decanted solution. Which chloride re-precipitated? (1 of the 3 will be different)

7. Examine your record and complete the flow chart which summarizes the steps you would use to analyze and unknown containing all three cations.

8. Analyze the unknowns starting with step #1. (Note: Make sure to react only 1 mL of your unknown with the HCl.)

#3, 5, 6 are critical steps

42


43


Data Table:Record your observations in the following flow charts as you complete the procedure. The flow charts are designed to correspond to the procedural steps.

44

Follow Step 2 Follow Step 2 Follow Step 2


Data Table for Unknown # _______

Unknown # ___________(The unknown could contain Ag+1, Pb+2, and/or Hg2

+2)

1 mL of your unknown reacts with 6M HCl

To 5 drops of the clear solution,

add 5 drops of K2CrO4 To the precipitate, add 3 mL of NH3

To less than 1 mL of the clear solution,

add 2-3 mL of HNO3

45


The Molar Volume of a Gas

Procedure:

1. Measure the length of a piece of magnesium ribbon no more than 2.5 cm. Cut the Mg square and measure accurately. Using the grams per meter conversion provided, calculate the mass of the magnesium. Return the Mg to its container immediately after cutting. Do not set aside on table.

2. Cut and wrap a piece of copper wire (approximately 15 cm) to form a “cage” around the magnesium. Thread one end of the copper wire through the hole in the rubber stopper so that the magnesium is suspended from the narrower end of the stopper.

3. Using a funnel, pour approximately 10 mL of 6.0 M HCl into the gas measuring tube.

4. Using a beaker or the distilled wash bottle, slowly add distilled water into the tube. Hold the eudiometer at an angle while filling to minimize the amount of water that mixes with the acid. Be sure to fill the tube to the very top so that there is no air in the system.

5. Place the stopper with the magnesium in the copper cage into the eudiometer tube so that the magnesium ribbon is inside the tube. Fill the holes of the stopper with distilled water.

6. Invert the tube into a large graduated cylinder. The eudiometer should not sit on the bottom of the graduated cylinder. Gently tap the eudiometer to release any trapped gas.

7. When the reaction stops, adjust the tube so that the water level in the tube is the same as the level in the large graduated cylinder. Equilibrate the pressure and record the gas volume at the point.

8. Measure the temperature of the water (assume this to be the gas temp) and the barometric pressure.

9. Repeat the procedure for a second trial.

46


Note: Calculations using R or 22.4 L/mol are not acceptable for this experiment. The value of R is derived from the actual molar volume. Since determining the molar volume is the purpose of this experiment, using the value of R or 22.4 L/mol is not mathematically appropriate.

Analysis: Work must be shown for Trial 1 only.

1. Write a complete balanced equation for the reaction that took place. Include all physical states.

2. Determine the mass of magnesium ribbon used.

Trial 1:____________ Trial 2:____________

3. Determine the number of moles of magnesium reacted.

Trial 1:____________ Trial 2:____________

4. Determine the number of moles of hydrogen produced.

Trial 1:____________ Trial 2:____________

5. Determine the partial pressure of hydrogen for each trial.

Trial 1:____________ Trial 2:____________

6. Given the volume, temperature and pressure of the hydrogen collected, determine the volume (L) of hydrogen, for each trial, at STP.

Trial 1:____________ Trial 2:____________

7. Determine what the volume of hydrogen gas produced at STP would be for every 1 mole of hydrogen.

Trial 1:____________ Trial 2:____________

8. Average these values to get your experimental value for the molar volume.

Molar Volume (experimental): _________________

9. Determine your percent error for this experiment.

Percent Error: __________________Problems:

1. What would the volume of hydrogen collected in trial 1 of your experiment be at 115.0 kPa and 87.5oC?

2. Using your experimental value for the molar volume (#8), calculate the volume of hydrogen that 47


would be produced at STP if a 10.0 g piece of magnesium is reacted completely.

48


Percent YieldProcedure:

1. Clean (soap and water) a beaker, an Erlenmeyer flask, and a funnel.

2. In a beaker, measure 2 grams of solid potassium iodide and record its mass. Add 15.0 mL of distilled water. Stir to dissolve completely.

3. Measure 10.0 mL of 1.0 M lead(II) nitrate solution.

4. Add the 1.0 M lead(II) nitrate solution to the beaker with potassium iodide and gently swirl.

5. Obtain a piece of filter paper and put your initials on the filter paper. Determine its mass.

6. Set up a filtering apparatus using a funnel and an Erlenmeyer flask. Fold the filter paper, place it in the funnel and wet it slightly with distilled water to adhere it to the funnel.

7. Begin to slowly filter the reaction mixture. Be sure not to allow the liquid level to rise above the top of the filter paper. The yellow precipitate should remain behind on the paper.

8. Rinse the beaker with a small amount of distilled water and filter it as well. Repeat rinsing the beaker until all of the precipitate is out of the beaker and onto the filter paper.

9. Carefully remove your filter paper from the funnel using a scoopula and forceps. Place the filter paper, still folded, on the watch glass and put it on the tray up front to dry.

10. Clean all glassware used with soap and return to the drawer. Wash your hands! 11. DAY 2: When dry, reweigh your filter paper and record the mass. Throw away the filter paper. Wash

the evaporating dish and return to your lab drawer.

Analysis:

1. Write a complete word equation for the reaction.2. Write a complete balanced equation for the reaction.3. Calculate the theoretical yield for the reaction4. Calculate the percent yield for the reaction.5. Determine the mass of excess reactant that remains for this reaction.

Questions:

1. It is likely that you do not end up with 100% yield for this reaction. Give sound, logical, chemical reasoning in your answers to the following two questions.

a. The % yield is greater than 100%. Give one reason why.

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b. The % yield is less than 100%. Give one reason why.

Titration 1

Objective: To determine the molar concentration of a hydrochloric acid solution by titrating it with a sodium hydroxide solution with a molarity of _______M.

General Titration Instructions

Buret Preparation:1. Clean the 2 burets with soap and water using the buret brushes. Only use a small amount of soap.2. Clamp the burets to a buret clamp attached to a ring stand.3. Open the spout of the buret. When the spout is parallel to the tip, it is open. 4. Add distilled water to the buret and allow the water to flow through the tip. This is to both rinse

the buret and to make sure that it is working properly.5. Position the buret so that the top of it is below eye level.6. Using a long stem funnel, add 5 – 10 mL of the solution to be added to the buret and allow that to

flow out.7. Close the spout and fill the buret with the solution. It is not necessary to fill it exactly to the zero

mark. Open the spout briefly to allow some of the solution to flow out of the buret to insure that there is no air in the tip.

8. If using two burets, be sure to label them.

Titration:1. Record the initial buret readings.2. Deliver a known volume (14-20mL) of one solution (the acid for this lab) to an Erlenmeyer flask

and add two drops of the indicator, phenolphthalein.3. Open the spout of the other solution (base) and begin to deliver this solution to the flask while

constantly swirling it.4. As the endpoint nears, you will notice the color changing briefly and then returning to the original

color. The closer the endpoint is, the longer the color remains. When close, the spout can be repositioned so that the solution is delivered dropwise. Continue adding the solution until the color change is permanent. The color must change due to the addition of a single drop. If more than one drop was added, add a small amount of the other solution to return it to the original color and repeat.

5. Once finished, record the final buret readings.6. A titration should be done at least three times.

Clean-Up:The burets are to be emptied of the solutions. They should be cleaned with a dilute soap solution and thoroughly rinsed. Tap water can be used for this process. Once cleaned, the burets should be rinsed with distilled water and stored upside down with the spouts open.

Analysis: Write a complete balanced equation for the reaction. Show your work for each molarity of acid calculation. Then determine the average molarity of your trials.

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Questions:

1. Obtain the actual molarity of the HCl solution from your teacher and calculate your percent error.

2. What happens in the titration during the color change of the indicator? Why is it important that the color change occur by the addition of a single drop?

3. Why is an Erlenmeyer flask preferred over a beaker when performing a titration?

4. Suppose calcium hydroxide was used in this experiment instead of sodium hydroxide. Assuming all experimental data was the same, what would be the molarity of the acid? Explain using calculations.

5. Suppose there was a large air bubble in the tip of the acid buret. Explain the effect that this would have on the calculated value of the acid’s molarity. Use calculations to show work.

6. A student titrated 30.00 mL of a hydrochloric acid solution with 1.00 M sodium hydroxide. The sodium hydroxide was initially filled to the 2.30 mL mark on the buret. Once the level in the buret reached 50 mL, the student was forced to refill the buret and did so to the 5.06 mL mark. The endpoint was finally reached when the sodium hydroxide level dropped to 32.09 mL on the buret. What is the molarity of the acid solution? Show work.

7. How many milliliters of a 0.250 M sulfuric acid solution would be required to completely react with 2.398 grams of solid aluminum hydroxide? Work must be shown.

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Titration 2

Determine the molarity of the HCl solution by titrating it with sodium carbonate.

Prepare sodium carbonate solution using a mass of sodium carbonate between 7 and 9 grams. Use a 250.0 mL volumetric flask.

o Note : The sodium carbonate used in this experiment may be anhydrous or it may be a monohydrate. Refer to the label on the jar to determine which it is because it must be considered in the molar mass determination. This must be included in the lab notebook!

Start with 20-25 mL of the base in the Erlenmeyer flask. Vary the amount for each trial.

The indicator to use is bromocresol green (approximately 6 drops per trial).

A minimum of 3 trials is required.

The unknown letter for the HCl must be included in your lab notebook.

Accuracy counts.

ALL DATA for sodium carbonate molarity and HCl titrations must be included in lab report.

Questions/Problems to be included in report. The answers need to be typed in the appropriate section of your lab report. The work must be shown in the sample calculations.

1. What is the minimum mass of sodium bicarbonate that must be sprinkled on 115.9 mL of the hydrochloric acid solution (your average molarity) that you titrated in order to completely neutralize it?

2. What volume of your sodium carbonate solution would need to be combined with 250.0 mL of 3.00 M nitric acid to completely neutralize it?

3. A 0.5425 g sample of an unknown monoprotic acid requires 12.97 mL of a 0.1025 molar solution of calcium hydroxide for neutralization in a titration. Determine the molar mass of the unknown acid.

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Titration 3: Determining the Molar Mass of an Unknown Acid

In this lab you will be determining the molar mass of an unknown solid acid by titrating it with a solution of NaOH of known molarity. Your acid will either be a monoprotic (HX), a diprotic, (H2X), or a triprotic (H3X) acid.

1. Think about the data you will collect and construct an appropriate data table and results table.2. Prepare your NaOH solution by dissolving between 1.20 and 1.40 grams of NaOH with deionized

water in a 100 mL volumetric flask. Record the mass of NaOH used.o Rinse and fill one buret with the NaOH solution.

3. Add approximately 0.30 gram of unknown acid to an Erlenmeyer flask and dissolve with 40 mL deionized water. Record the mass of the acid used. Add 3-5 drops of phenolphthalein indicator. Be sure that all the acid is dissolved before titrating.

o Perform 4 trials

Analysis:1. Calculate the molar mass of the acid. (Is it monoprotic, diprotic, or triprotic?)2. Calculate the percent error for your results.3. What would be the molar mass of a 1.50 gram sample of a triprotic acid (H3X) that is titrated to

the endpoint with 15.75 mL of a sodium carbonate solution that has the same molarity as your NaOH solution?

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Heat of Reaction

Procedure:

1. Measure 50 mL of the hydrochloric acid and pour it into the calorimeter.

2. Measure and record the temperature of the acid solution.

3. Weigh approximately 2g of sodium hydroxide pellets. DO NOT TOUCH THE PELLETS! Record the actual mass.

4. Carefully place the pellets into the acid and insert the thermometer.

5. Gently swirl the cup to mix the contents. Record the highest temperature reached for the mixture.

6. Repeat the procedure using 4.0g of NaOH.

***Assume the density and specific heat of the solution are the same as water’s values.***

Analysis:

1. Write a complete balanced equation for the reaction that occurred.

2. Calculate the heat of reaction (∆H) in kJ per mole of NaOH for each trial using the temperature data. Work must be shown.

∆H (trial 1) = ____________________ ∆H (trial 2) = ____________________

3. Determine the average value of ∆H for your two trials. This is your experimental value.

∆H (average) = ____________________

4. Determine the ∆H for the reaction using the heats of formation. This is your accepted value. Work must be shown.

5. Calculate percent error.

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Determining Solution Concentration: Using a Spectrophotometer

IntroductionThe spectrophotometer is a powerful tool which can be used for colorimetric determination of

concentration. The process is based on the fact that colored ions absorb light from the visible spectrum. The greater the concentration of the ions, the greater the absorbance (A) of light.

Conversely, the more light that is absorbed by the ions in solution, the less light that is transmitted through the solution. Thus, the inverse of absorbance is percent transmittance (%T). Therefore, concentration can be measured using absorbance or percent transmittance.

To determine the concentration of a colored ion in solution, a set of carefully prepared solutions of known concentration must be first measured for absorbance or percent transmittance. The spectrophotometer should have the wavelength setting at a previously determined maximum absorbance (or %T) value for the ion in question while testing the standards. A graph plotting the absorbance (or %T) against concentration data for the standards gives a calibration curve. Then, the absorbance (or %T) can be measured for a solution of unknown concentration, then matched with the calibration curve to determine the concentration.

The cobalt ion, Co2+, concentration will be determined in this experiment and should be expressed in units of molarity. The absorption maximum (%T minimum) for Co2+ occurs at a wavelength setting of 510 nm. The percent transmittance, %T, scale will be used to produce a calibration curve.

Procedure1. Make 50.0 mL of a 0.10 M Co(NO3)2 · 6 H2O standard stock solution. Show your calculations for

this step.

2. Using the stock solution and a small graduated cylinder, prepare the solutions indicated below in test tubes labeled 1 – 5. Each solution should have a total volume of 10.0 mL.

Test Tube #1: 0.02 MTest Tube #2: 0.04 MTest Tube #3: 0.06 MTest Tube #4: 0.08 MTest Tube #5: 0.10 M

Show work for the dilution calculations for test tubes 1 – 4

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3. Obtain 1 disposable test tube, your 5 prepared solutions, a wash bottle and a paper towel and proceed to a spectrophotometer in the room. It is convenient to stand your prepared solutions in a beaker.

4. The spectrophotometer should be warmed up and the wavelength set to 510 nm. The device needs to be zeroed. With the sample compartment empty and closed, adjust the %T (transmittance) to 0 with the left front knob.

5. Place a disposable test tube filled with distilled water, into the sample compartment and adjust the %T to 100% T with the right front knob (this means all of the light travels through the totally clear water). Be sure to wipe all liquid and smudges off of the tubes before placing in spectrophotometer! In addition, no bubbles should be evident int eh test tube.

6. Remove the distilled water tube and empty it. Fill it approximately ¾ full with the solution in Test Tube #1. Wipe the outside of the test tube and insert it into the compartment. Record the absorbance. Repeat for Test Tubes 2–5, but be sure to rinse the disposable test tube with distilled water, then with the next prepared solution between uses. Start with the lowest concentration and work up to the highest concentration.

7. Construct a calibration graph plotting absorbance on the y-axis and molarity on the x-axis

8. Once the graph is complete, determine the absorbance for unknown A and unknown B. It will be necessary to recalibrate the machine before doing this by following procedure 4. Using your graph, determine the molarities for the two unknowns.

Conclusions

1. The actual concentrations of the unknown solutions were A = 0.075 M and B = 0.050 M. Calculate the percent error of your results for A and B.

2. Using your calibration graph, determine the absorbance of a 0.036 M and 0.072 M solution of Co2+.

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Flame Test DemonstrationIntroduction: As electrons absorb energy, they jump to a higher energy level called an excited state. Electrons in excited states are not stable and fall to lower energy levels in order to become more stable. When they fall, they release energy in the form of electromagnetic radiation. Visible light, the only type of electromagnetic radiation that is detectable to the human eye, is emitted when electrons in an element are excited. The light emitted from that element becomes a fingerprint for that element because it does not include every color in the spectrum.

The specific spectrum for an element is called a line spectrum because it is made up of only certain colors. When using a spectroscope, a researcher can differentiate the colors emitted when that element is excited. However, with the naked eye, only a blend of the colors is noticed. In this lab, we will be completing flame tests to determine the characteristic spectral color of certain elements. Even though there are many other colors in an element’s line spectrum, the color noticed during the flame test is a blend of the colors.

Materials: Goggles Apron BaCl2 (aq)

Cotton Swabs Crucible tongs Cu(NO3)2(aq)

Bunsen Burner Ba(NO3)2 (aq) Sr(NO3)2 (aq)

CuCl2 (aq) SrCl2(aq) LiNO3(aq)

Ca(NO3)2 (aq) NaCl(aq) CaCl2 (aq)

NaNO3 (aq) Unknown X Unknown YUnknown Z

Procedure: Make sure the burner is lit and has a blue or almost clear flame. With your tongs, pick up the end of a swab and soak the cotton end in the solution. Hold the soaked-end of the swab in the clear part of the flame and record the flame color in the Data Table. Eventually the swab will burn giving a characteristic yellow color. Be sure you are recording the solution’s flame color. Placed the used swab in the trash.

Critical Thinking and Application:

1. According to your data, determine the characteristic color produced when the following metals are excited: Lithium, Sodium, Calcium, Copper, Strontium, and Barium.

2. Using your data, identify the metal present in the 3 unknown solutions.

3. When a glass rod is heated, a yellow flame is observed around the point of heating. What does this yellow flame indicate? Why is it observed when glass is heated?

4. A reddish brown rock was held in a very hot burner flame. The flame appeared green in color. What metal was most likely present in the rock.

5. Based on your results and observations, would this method be practical to determine metals in a mixture? Explain.

6. In your own words, explain how the color is produced. (I am not looking for a description of the lab, but an explanation of the electron movement and its relationship to the color.)

7. List two possible sources of error in this lab. 57


Periodic Law1. Use the regular periodic table to draw or highlight the zigzag line (staircase).2. Place the atomic numbers in the lower left hand corner and the atomic masses to the tenths in the

upper right hand corner.3. The following sets of elements appear as GROUPS: O, G, CC, II, QQ ; D, KK, X, L, GG ;

U, J, Z, S, K, HH ; A, PP, I, Y, AA ; T, DD, FF, LL, E ; R, V, EE, F, N, B ; C, OO, M, W, JJ ; MM, H, P, Q, BB ;

_________________________________________________________________________1) EE is an alkali metal.2) Y has an outer electron configuration of 4s2.3) U is a noble gas.4) T has an atomic mass of 32 amu.5) B is a gas at room temperature. 6) I has the smallest atomic radius in its group.7) K has an electron configuration that ends in 6p6.8) C is an element that is used in fertilizer.9) R has a lower first ionization energy value than N and V but a higher value than F.10) Y is the metallic component of limestone. 11) D is the most electronegative element in the group.12) LL is a metalloid.13) OO has the smallest electron affinity of the group.14) KK is a halogen that sublimates.15) Q has the most energy levels in the group.16) CC has one more proton than I.17) V has an outer subshell configuration of 3s1.18) J has a smaller radius than Z, but a larger radius than S.19) L is a dark-red liquid.20) G has a larger electronegativity than QQ but a smaller electronegativity than O.21) H has two allotropic forms called diamond and graphite.22) F is a liquid at room temperature.23) A has a larger first ionization energy than PP and AA.24) FF is the most abundant element in the earth’s crust.25) II is the least metallic metal. 26) C is especially stable because of a half-filled “p” subshell.27) Both P and BB are metalloids but BB has a lower ionization energy.28) AA has the largest atomic size in the set.29) Z has a total of 18 protons.30) W is the most abundant element in the atmosphere.31) N is the first alkali metal with a completed 3p.32) HH has one more proton than L.33) E is the most metallic in this group.34) Both JJ and M are metalloids, but M has more metallic properties.35) O has a greater first ionization energy than G, but a lower first ionization energy than II.36) MM comes from the Latin word stannous.37) PP has a lower electronegativity than Y and A, but a higher electronegativity than AA. 38) GG is radioactive.39) DD has two half-filled “p” orbitals in the fourth energy level.40) C has one less electron than T.

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1A 8A

1

2A 3A 4A 5A 6A 7A

2

3

4

5

6

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QUESTIONS:

1. Which has a larger radius? R or F C or X

2. Which has the highest electronegativity? EE or D X or KK

3. Which has the lowest ionization energy? B or F V or A

4. Which has a high 1st I.E. due to a filled subshell? J or W V or A

5. Which probably has the highest electron affinity? D or KK N or L

6. Identify the make-believe element that corresponds to:

_______a) Atomic number 12

_______b) Atomic mass 84

_______c) 3s23p3

_______d) 4s24p1

_______e) 10 electrons

7. Which make believe element is:

______a) the most metallic in group 2A

______b) the most metallic in period 1

______c) the most nonmetallic in group 3A

______d) the most nonmetallic in period 3

8. What charge are you most likely going to find on the following ions?:

N _____ W ______ KK ______ EE ______ Q ______ T ______

9. Identify the following formulas as either CORRECT (C) OR INCORRECT (I):

AX2 ____ QT2 ______ VW3 ______ RX _____ N3M ______

10. Finish writing and balance the following double replacement equations:

a) ID2 + (EE)3C ------->

b) RX + Y(LL) ------->

11. Write balanced composition reaction equations for the following:

a) R + X2 ----->

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b) V + LL ------>

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Building Molecular Models

molecular formula

Lewis Structure(Dot Diagram)

Structural Formula(drawn to shape)

Molecular Geometry around Central Atom(s)

Bond Angles(s) Polar? Teacher's

Initials

H2

HBr

PF3

CH4

N2

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molecular formula





Initials

CH3NH2

CO2

H2CO3

C2H2

63


CH3Cl

molecular formula





Initials

HCOOH

HCN

H2O2

CH2Cl2

64


H2CO

molecular formula





Initials

C2H4

O2

NF3

65


CH3CH2CH3

CH2CHCH3

molecular formula





Initials

CH3OH

SCl2

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CF4

Cl2CO

ClNO

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chemistry 6 - north penn school district / · web viewheat of fusion of ice ....25 qualitative...

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