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BELL WORK 3-10-14

What is a chemical solution? Try to explain it as if to a 5th grader, be

as “scientific” as possible!

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Homework Packet Turn-In1. Pressure Conversions-ppt. 1-6

2. White review—Boyles’ 1-4

3. White review Charles’ 5-8

4. White review Combined 9-13

5. White Review Mixed 14-20

6. Ideal and Combined (white sheet) 1-19 odds.

7. Gas Stoichiometry (white sheet) 1-4, 5-10.

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10 March 2014

Agenda:

Solutions

Solubility

Molarity

Objective: You will KNOW the parts of a solution, UNDERSTAND how to calculate molarity, and tommorow APPLY your knowledge to making solutions

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Concentration and Reaction Rates Video

http://www.youtube.com/watch?v=kjKyEdrVXJA

5Some Definitions

A solution is formed when a ____________ and _____________are mixed.

Solvent

Solute

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PARTS OF SOLUTIONSSOLUTE –what’s being

dissolved (usually the lesser amount)

SOLVENT –what’s dissolving the solute (usually the greater amount)

Solute + Solvent = Solution

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Definitions

Solutions can be

saturated or unsaturated.

__________solution contain the maximum amount of solute.

An __________solution contains less solute than a solvent can hold at a particular temp.

Saturated

unsaturated

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Definitions

SUPERSATURATED SOLUTIONS contain more solute than a solvent can hold

They are unstable. The super saturation is only temporary, and usually accomplished in one of two ways:

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To Make a Supersaturated Solution

1. Warm the solvent so that it will dissolve more, then cool the solution

2. Evaporate some of the solvent carefully so that the solute does not solidify and come out of solution.

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SupersaturatedRock Candy

Crystal Rock candy

This supersaturated sucrose and food coloring solution uses a “seed” crystal to make…

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Factors affecting solubility—dissolve

1. _______ increases solubility in most liquids

* solubility of_________ are greater in cold water than hot.

2. ________ the solubility of gas increases w/ increasing pressure

Heat

gases

True:

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Polarity Review

• http://www.youtube.com/watch?v=PVL24HAesnc

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Factors affecting solubility

3. __________ molecules will only dissolve in _________ molecules

Non- polar molecules will only dissolve in non-polar molecules

“_________dissolves__________”

Polar

Polar

like like

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Polarity Recall"polar" molecules: An uneven distribution

of electron density. Ex. water H2O

“non polar” molecules: an even distribution of electron density.

Ex. Oil, propane, etc.

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QuestionA solution is made up of 25 grams of

cyclohexane (non-polar) and 7 grams of acetonitrile (polar).

What is the solute ?

What is the solvent?

Would you expect the solvent to readily mix with the solute?

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With your neighborMr. Brunenkant tried to mix

1-butanol (non-polar) with cyclohexane (non-polar) to make a solvent that would clean a water soluble crystal residue on his desk.

1. Will the two solvents mix readily?

2. Do you think the solvent mixture would dissolve the water soluble crystals? Why or why not?

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The amount of solute in a solution is given by its concentration.

M = mol

L

Molarity (M) = moles soluteliters of solution

Concentration of a solution

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Less than 1.0 L of

water was used to

make 1.0 L of

solution. Why?

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Dissolve 5.00 g of NiCl2 in enough water to make 250 mL of solution.

Calculate the Molarity.

Practice

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Step 1: Calc. moles of NiCl2

mol 0.0388 = g 129

mol 1 • g .005

M 0.155 = L 0.250

mol 0.0388Step 2: Calculate Molarity

[NiCl2] = 0.155 M

Dissolve 5.00 g of NiCl2 in enough water to make 250 mL of solution. Calculate the Molarity.

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Step 1: Calc. moles of NiCl2in 100ml

0.1M sol.

Step 2: Calculate grams

0.100L x 0.1mol/L = 0.01moles

0.01mol x 129g/mol = 1.29grams

What amount (grams) of NiCl2 is needed to make a 0.1M solution

at a volume of 100ml?

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Step 1: Calc. moles of NaCl in 500ml 0.5M sol.

Step 2: Calculate grams

0.500L x 0.5mol/L = 0.25moles

0.25mol x 58g/mol = 14.5grams

What amount (grams) of NaCl is needed to make a 0.5M solution

at a volume of 500ml?

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ClosureWrite down your answer:

1.What is a chemical solution?

2.What is a solute?

3.What is a solvent?

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Homework1. What is the molarity of 7 g of NaCl in

300 mL of water?

2. What is the molarity of 12 g of KBr in 700 mL of water?

3. If you have a 0.7 molar NaCl solution, how many moles of NaCl are there in 1200 mL?

4. Based on your answer from #3, how many grams would that be?

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BW 3-12-13

1) What is the molarity if you have 3.7 moles and 2.1 L?

2) If you dissolve 10.00 g of CaCl2 in enough water to make 500 mL of solution, what is the Molarity?

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12 March 2013

Agenda:

Molarity

Practice

Objective: You will understand molarity and how to calculate it.

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moles = M•V

What mass of oxalic acid, H2C2O4, is required to make 250. mL of a 0.0500 M solution?

Using Molarity

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Step 1: mL L.

250 mL x 1L/1000mL = 0.250 L

Step 2: Calculate.

Mol=(0.05 mol/L) (0.250 L) = 0.0125 mol

Step 3: Convert moles grams.

(0.0125 mol)(90.00 g/mol) = 1.13 g

moles = M•Vmoles = M•V

What mass of oxalic acid, H2C2O4, is required to make 250. mL of a 0.05 M solution?

Using Molarity

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PracticeHow many grams of NaOH are required to prepare 400 mL of 3.0M NaOH solution?

1) 12 g

2) 48 g

3) 300 g

30Practice makes Perfect

Calculate the molarity when 75.0 grams of MgCl2 is dissolved in 500.0 mL of solution.

100.0 grams of sucrose (C12H22O11)is dissolved in 1.50 L of solution. What is the molarity?

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Molarity Pre-lab time!

• Get a sheet of paper out and title it:

Determining Molarity Lab

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HW: Problems 1-11 odds

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BELL WORK 3-13-13

What is the molarity of a solution with 6.2 grams of HNO4 dissolved in 350ml of water?

If molarity of HNO4 is .090 M and you have 5 liters, how many moles is that? Grams?

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Happy Pi Day!BELL WORK

3-14-131. 49.8 grams of KI is dissolved in

enough water to make 3.14 L of solution. What is the molarity?

2. What makes up a solution?

3. How do you increase solubility?

4. What type of substance does a polar substance dissolve in?

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Bell Work 3/15/20131. What is the molarity of a solution if it

has 7 moles of HCl and there are 2.1 L of solution?

2. How many grams of KBr must you weigh out in order to make 500 mL of a 3M solution?

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15 March 2013

Agenda:

Dilutions

“Killer Kool Aid Lab”--Friday

Objective: you will understand how to use the dilutions formula and apply it in a laboratory setting

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DILUTIONGoing from one concentration to another

M1V1=M2V2

M = molarity (mol/L)

V = volume (what unit ????)

Starting/ what you have M1 and V1

Ending/ what you want M2 and V2

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4.5

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Dilution is the procedure for preparing a less concentrated solution from a more concentrated

solution.

Dilution

Add Solvent

Moles of solutebefore dilution (i)

Moles of soluteafter dilution (f)=

M1V1 M2V2=

4.5

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M1V1 = M2V2

M1 = 4.00 M2 = 0.200 V2 = 0.06 L V1 = ? L

V1 =M2V2

M1

=0.200 x 0.06

4.00= 0.003 L = 3 mL

3 mL of acid + 57 mL of water= 60 mL of solution

How would you prepare 60.0 mL of 0.2M HNO3 from a stock solution of 4.00 M HNO3?

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DILUTIONWhat would the new molarity be of a 250ml 0.8M solution of HCl if it was diluted to 450ml?

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PracticeWhat is the molarity of a solution with 2.0 grams of NaOH dissolved in 300ml of water. What would be the new molarity if you diluted to solution of 630ml?

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Bellwork 3-18-13

How many moles of KNO3 are needed to create 500 mL of 6.0M solution of KNO3?

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Lab TimeKiller Kool Aid!!!

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Lab TimeKiller Kool Aid!!!

So, group 1 does dilutions for Red 2.2M 0.176, Blue 1.50M 0.135M, Green 3.60M 0.324M.

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Preparing SolutionsPreparing SolutionsPreparing SolutionsPreparing Solutions

Weigh out a solid solute and dissolve in a given quantity of solvent.

Dilute a concentrated solution to give one that is less concentrated.

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TitrationsIn a titration a solution of accurately known concentration is added gradually added to another solution of unknown concentration until the chemical reaction between the two solutions is complete.

Equivalence point the point at which the reaction is complete

Indicator – substance that changes color at (or near) the equivalence point

Slowly add baseto unknown

acidUNTILthe indicator

changes color

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H2C2O4 (aq) + 2NaOH (aq) Na2C2O4 (aq) + 2H2O (l)

acid base

Carry out this reaction using a TITRATION.

Oxalic acid,Oxalic acid,

HH22CC22OO44

Acid Base Rxn Titration

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Setup for titrating an acid w/ a base

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TitrationTitration1. Add solution from the buret.

2. Reagent (base) reacts with compound (acid) in solution in the flask.

3. Indicator shows when exact stoichiometric reaction has occurred. (Acid = Base)

This is called NEUTRALIZATION.

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For most Acid-Base Rxns

The generic equation for most acid base rxn is:

AH + BOH AB + H2O

You will get a salt and water out of an acid base rxn!

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You try… write out the products:

AH + BOH AB + H2O

You will get a salt and water out of an acid base rxn!

1) HCl + NaOH

2) HNO3 + KOH

3)TrickyCH3COOH + NaOH

NaCl + H2O

KNO3 + H2O

NaCH3COO + H2O

Acetate ion

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volume acid moles acid moles base volume base

H2SO4 + 2NaOH 2H2O + Na2SO4

4.50 mol H2SO4

1000 mL solnx

2 mol NaOH

1 mol H2SO4

x 1000 ml soln

1.420 mol NaOHx

25.00 mL = 158 mL

M

acid

Mole

Bridge

M

base

What volume of a 1.420 M NaOH solution is required to titrate 25.00 mL of a 4.50 M H2SO4 solution?

WRITE THE BALANCED CHEMICAL EQUATION!