Grade 7 Science

Unit 3: Mixtures and Solutions

Chapter 8: Some substances dissolve to form solutions faster and more easily than others.

Name: __________________________Section: ____________

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Making Solutions

When you mix two substances they form a ____________________

Solutions have two parts

For each situation identify the solute and the solvent:

Situation Solute SolventA. Brass is used to make many

objects. Brass is a solution of zinc metal in a copper metal

B. Hydrogen peroxide is used to disinfect cuts. Hydrogen peroxide is a solution of 3% hydrogen and 97% water.

C. Dental amalgam is a metal that is used to fill cavities. It is a solution of mercury in tin.

D. Deicing fluid is a cleaner used to clean car and truck windshields. It is made up of a solution of propylene glycol in water.

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The substance that dissolves(found in less amounts)ex: sugar

The substance in which the solute dissolves.(found in the greatest amount)Ex :water

DissolvingDefinition:Dissolve ________________________________________________________________________________________________________________________________________

How are substances soluble?

According to the particle theory of matter, “there are _____________forces between the

particles”. In order to dissolve the _______________must be more strongly attracted to

the solvent than to themselves. This is means the solute is ____________in the solvent.

If something is ABLE to dissolve then it is _________________________.Ex: __________________________________________________________________

How are substances insoluble?

If the particles of the ____________ are more attracted to their own particles than the

solvent particles, ______________does not occur. The solute is said to be __________

in that solvent.

If something is UNABLE to dissolve then it is _______________________.Ex: __________________________________________________________________

Soluble or Insoluble?

Solvent or not??

Some materials are good ___________ for some solutes but not for others.

For example, ____________________________________________________________

Complete Activity 8 -1C Page 259

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“Does it Dissolve?”

Different states of matter of Solutes and solvents.Solvents and solutes can be different states of matter.

Fill in the state of matter for each solute and solvent in the given solution

Solution Solute Solvent State of solute State of solventSoda water Carbon dioxide WaterVinegar Acetic acid WaterSalt water salt WaterBrass zinc Copper

Concentration (p. 262)

The two cups below each had hot water with a tea bag sitting in them. The time below the cup indicates how long the tea bag has been in the cup.

10 mins 2 mins

______________________________ _________________________________

Definition:______________________ Definition:________________________________________________________ __________________________________________________________ __________________________________________________________ ____________________________

Directions:

1. Supposing these were clear cups, use a brown lead to color how dark you think the tea would be in each cup.

2. Write the statement dilute solution or concentrated solution under the cup you think it describes.

3. Write the definition for each statement in the space provided

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Describing Concentration

The quantity of _____________that is dissolved in a certain quantity of the __________.

Concentration can be described two ways:

Qualitative or Quantitative?

Statement Qualitative QuantitativeFood coloring made the water blue.Adding 3 mL of food coloring turned 250 mL of water blue.The water became warmer.The water’s temperature increased by 5 degree Celsius.We needed just over a dozen floor tiles for our model room.We needed 14 floor tiles for our model room.The liquid boiled in 5 min.The liquid took only a few minutes to boil.The mass of this solid is 5g more than that one.This solid is heavier than that one.He drinks eight glasses of water each day.He drinks 2L of water each day.

Question: If you were a diabetic and had to watch you sugar intake, would you want to know the concentration of a drink qualitatively or quantitatively? Why?

______________________________________________________________

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“With numbers”such as units of grams

per litre (g/L)

“With words” like dilute and concentrated

Complete Math and Science Connect P. 272

1. Convert each of the following from mL to L.

a) 1000 mL = __________________ L

b) 500 mL = ___________________ L

c) 100 mL = ___________________ L

d) 10 mL = ____________________ L

e) 5 mL = _____________________ L

f) 1 mL = _____________________ L

2. Convert each of the following from g/mL to g/L.

a) 10 g/ 100 mL = _______________________

b) 52 g/ 100 mL = _______________________

c) 65 g/ 100 mL = _______________________

d) 100g/ 100 mL = _______________________

e) 137g/ 100 mL = _______________________

f) 0.15g/ 100 mL = _______________________

Saturated vs. Unsaturated Solution

(Refer to p.264)

Define:

Saturated Solution:

________________________________________________________________________

____________________________

Unsaturated Solution:

__________________________________________ ______

____________________________________________________

Question:

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1. If there are two glasses on Kool Aid on the table, one is unsaturated the other is

saturated. How would you be able to tell the difference between the two?

________________________________________________________________________

____________________________________________________

2. It is possible to “unsaturate a saturated solution”. Suggest ways you might be

able to do this. (Hint: How could you make more sugar to dissolve in a glass of

water?)

________________________________________________________________________

____________________________________________________

______________________________________________________________

Solubility

(Refer to p. 264)

Define:

Solubility:

________________________________________________________________________

____________________________________________

Factors that effect the Rate of dissolving

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Factor How does it affect the solubility?

A. Size of Solute

B. Temperature

C. Pressure

Grade 7 Science Core Lab Activity 8-2A Pages 268-9

Unit 3: Mixtures and Solutions

How Does Temperature Affect Solubility?

Procedure: Part 1 Refer to text page 268.

Complete the graph on the graph paper provided on the next page.

Questions:1. Describe the shape of the lines on your graph.

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2. What happens to the lines as the temperature increases?

3. Predict the solubility of each solute at 90 degrees Celsius? Sucrose Potassium Chlorate Ammonium Chloride

Title: ___________________________________________________________________

Part 2:

Name: ______________________________

Partners: ____________________________ ____________________________

____________________________ _____________________________

Problem: How does temperature affect the solubility of a solid in a liquid solvent?

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Hypothesis:

Materials: graduated cylinder thermometer beakersugar cubes stopwatch

Procedure: Measure 100 mL of cold water for one beaker. Measure 100 mL of hot water for another beaker. Record the initial temperatures of both beakers. Drop one sugar cube in each beaker and record the amount of time it takes to

completely dissolve.Results:

Sugar Mixture Temperature Temperature (Class Average)

Time Time(Class Average)

ColdHot

Analyze:

How did the solubility in warmer water of the substance you tested compare with its

solubility in colder water?

________________________________________________________________________

________________________________________________________________________

________________________________________________________________________

Key Terms

Dissolves________________________________________________________________________________________________________________________________________________

Insoluble

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________________________________________________________________________________________________________________________________________________

Soluble________________________________________________________________________________________________________________________________________________

Solute________________________________________________________________________________________________________________________________________________

Solvent________________________________________________________________________________________________________________________________________________

Concentrated Solution________________________________________________________________________________________________________________________________________________

Concentration________________________________________________________________________________________________________________________________________________

Dilute Solution________________________________________________________________________________________________________________________________________________

Saturated Solution________________________________________________________________________________________________________________________________________________

Solubility________________________________________________________________________________________________________________________________________________

Unsaturated Solution________________________________________________________________________________________________________________________________________________

Comprehension Questions

1. a) Vinegar in insoluble in vegetable oil. Does this mean that vinegar is a totally insoluble substance?__________________________________________________________________

b) Why or why not?

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____________________________________________________________________________________________________________________________________

2. List two substances that are soluble in water.

i) ____________________________________________________________ii) ____________________________________________________________

3. List two substances that are insoluble in water.

i) ____________________________________________________________ii) ____________________________________________________________

4. Name a substance that is insoluble in water but is soluble in a different solution.__________________________________________________________________

5. You put 3 teaspoons of sugar in jug and you put 2 teaspoons of sugar in another jug exactly the same size. Which jug is more concentrated?__________________________________________________________________

6. What does the units g/L mean?____________________________________________________________________________________________________________________________________

7. What is the difference between a saturated solution and an unsaturated solution?______________________________________________________________________________________________________________________________________________________________________________________________________

8. Explain this statement: “The solubility of salt is 357 g/L at 0℃.______________________________________________________________________________________________________________________________________________________________________________________________________

9. How does the size of the solute affect the rate of dissolving?____________________________________________________________________________________________________________________________________

10. Refer to Table 8.2 on page 264.a) Which is the most soluble substance? ________________________________b) Which is the least soluble substance? ________________________________

11. a) Suppose that you add some solid detergent to the water in a washing machine. Then, you decide that your clothes are really dirty, so you add more detergent. Is the solution of detergent and water more concentrated or more dilute? Explain.________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

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Temperature (0℃¿ Solubility in Water (g/L)Sugar Potassium Chlorate Ammonium Chloride

10 1910 50 32020 2040 70 37030 2200 110 41040 2390 150 46050 2610 210 50060 2870 270 55070 3200 340 600

12. Using the table above, which solute has the highest solubility at each of the following temperatures?

a) 20℃ ______________________b) 60℃ ______________________c) 90℃ ______________________

13. Why must you include information about temperature when you state the solubility of a substance?______________________________________________________________________________________________________________________________________________________________________________________________________

Goal • Use this word search puzzle to review Key Terms from Chapter 8.

Create a list of 11 words from the descriptions below. Then find the words in the puzzle that follows.1. A solution in which the amount of solute is high compared to the amount of solvent2. What happens to a solute such as sugar when it is mixed with water3. A word used to describe a substance such

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as glass when it is mixed with water4. The opposite of the term you found for number 15. A solution that has as much solute dissolved in it for a given temperature6. A word used to describe a substance such as motor oil when it is mixed with gasoline7. The amount of solute that will dissolve in a given quantity of solvent at a certain temperature8. Another name for a homogeneous mixture9. A word used to describe a mixture such as salt water in which you can still dissolve more salt10. Term used for what you mix into a substance such as water to form a solution11. Term used for what you mix with a substance such as salt to form a solution

Goal • Check your understanding of Chapter 8.

What to DoCircle the letter of the best answer. 1. Which of the following statements accurately describes a solution

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of copper in silver?A. The copper is the solute and the silver is the solvent.B. The copper is the solution and the silver is the solvent.C. The silver is the solute and the copper is the solvent.D. The silver is the solution and the copper is the solvent.

 2. Which of the following statements is true?A. Chlorophyll is soluble in water.B. Gasoline is insoluble in motor oil.C. Gasoline is soluble in motor oil.D. Salt is insoluble in water.

 3. How is a concentrated solution different from a dilute solution?A. The concentrated solution has a large mass of dissolved solvent for a certain quanity of solute.B. The concentrated solution has a large mass of dissolved solute for a certain quantity of solvent.C. The concentrated solution has a small mass of dissolved solute for a certain quantity of solvent.D. They both have different solubilities.4. Which statement best describes what is meant by the term “rate of dissolving?”A. how fast a mixture must be stirredB. how fast a solute dissolves in a solventC. the solubility of a substance at a given temperatureD. the temperature at which a solute dissolves in a solvent

 5. What happens when you remove the cap from a bottle of pop?A. The pressure inside the bottle lowers very quickly.B. The pressure inside the bottle remains the same at a certain temperature.C. The pressure inside the bottle rises very quickly.D. The solution increases in pressure at a certain temperature.

6. At 0°C, 357 g of salt will dissolve in 1 L of water. At this temperature, why will no additional salt dissolve?A. The rate of dissolving is equal to its solubility.B. The solution is concentrated.C. The solution is saturated.D. The solution is unsaturated.

Match the term on the left with the best description on the right.Each description may be used only once.

Term Description

_____  7.solute_____  8.solubility_____  9.solution

A. describes a substance that will dissolve in another substance

B. the mass of a solute that can dissolve in 15

_____ 10. solvent_____ 11.saturated_____ 12.soluble

a certain amount of solvent at a certain temperature

C. the mass of a solvent that can dissolve in a certain solute at a certain temperature

D. the substance in which something dissolves

E. a homogeneous mixtureF. the substance that dissolves in another

substanceG. describes a solution in which no more

solute will dissolve at a certain temperature.

H. describes a solution in which no more solute will dissolve

Short Answer Questions13. Give examples of each of the following.

solid-in-solid solutions

(1) ______________________ (2) ______________________

liquid-in-liquid solutions

(1) ______________________ (2) ______________________

gas-in-gas solutions (1) ______________________

14. Use the particle theory of matter to explain why some substances are soluble in water while other substances are not soluble in water._______________________________________________________________________

__________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

15. Suppose that you have a solution of table salt dissolved in water. Explain how you could find out whether or not this solution is saturated.________________________________________________________________________________________________________________________________________________________________________________________________________________________

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_____________________________________________________________________________________________________________16. The solubility of sugar in water is 1792 g/L at 0°C. How much sugar must be added to 50 mL of water to make a saturated solution at 0°C?__________________________________________________________________________________________________________________________________17. The solubility of a substance can be expressed qualitatively and quantitatively. Use examples to explain this statement for sugar dissolved in water.____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

18. In the space to the right, sketch the shape of a graph that shows how the solubility of sugar in water changes as the temperature of the water increases. Label the axes correctly, and title the graph.

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