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Terms

• Soluble

• Insoluble

• Saturated solution

• Unsaturated solution

• Supersaturated solution

• Concentration

• Molarity

• Dilution

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Chapter 15Chapter 15

SOLUTIONSSOLUTIONS

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Some solutions contain Some solutions contain ELECTROLYTESELECTROLYTES

HCl, MgClHCl, MgCl22, and NaCl are , and NaCl are strong strong electrolyteselectrolytes. - . - dissociate completely into dissociate completely into ions.ions.

weak electrolytesweak electrolytes. . - - dissociate a little into ions.dissociate a little into ions.

Aqueous Aqueous SolutionsSolutions

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Aqueous Aqueous SolutionsSolutions

Some compounds dissolve in Some compounds dissolve in water but do not conduct water but do not conduct electricity. They are called: electricity. They are called:

nonelectrolytnonelectrolytes.es.

Examples include:Examples include:sugarsugarethanolethanolethylene glycolethylene glycol

Examples include:Examples include:sugarsugarethanolethanolethylene glycolethylene glycol

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Colligative PropertiesColligative Propertiesdepend on the concentration of particles in a solution, not of the identity of the particles.

Boiling Point Elevation Freezing Point Depression Osmotic Pressure

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Freezing Point DepressionFreezing Point Depression

Each mole of solute particles lowers the freezing point of 1 kilogram of water by 1.86 degrees Celsius.

Each mole of nonvolatile solute particles raises the boiling point of 1 kilogram of water by 0.51 degrees Celsius.

Boiling Point ElevationBoiling Point Elevation

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Electrolyte or Nonelectrolyte!Electrolyte or Nonelectrolyte!

Test each sample to see if it is a strong

electrolyte, weak electrolyte, or nonelectrolyte.

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Parts of a SolutionParts of a Solution

• SOLUTE –part that is being dissolved

• SOLVENT – part that dissolves the solute

• Solute + Solvent = Solution

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How Salts dissolve

O H

H HO

HHO

HH

O

HH

O

H HOH

H OH

HO

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Dissolving and Solutions

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Solubility curve

Saturated

Unsaturated

Supersaturated

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Solubility curve

• Any point on a line represents a saturated solution.

• In a saturated solution, the solvent contains the maximum amount of solute.

• Example

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Solubility curve• Any point below a

line represents an unsaturated solution.

• In an unsaturated solution, the solvent contains less than the maximum amount of solute.

• Example

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Solubility curve• Any point above a line

represents a supersaturated solution.

• In a supersaturated solution, the solvent contains more than the max solute.

• It is unstable • TemporaryTemporary

• accomplished in one of accomplished in one of two ways:two ways:1.1. Warm the solutionWarm the solution

2. Evaporate some of the solvent

• Example

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Solubility curve

Any solution can be made saturated, unsaturated, or supersaturated by changing the temperature.

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Solubility Curve

Determine if each of the following is unsaturated, saturated, or supersaturated.

•55g of NH3 at 20oC._________

•80g of NaNO3 at 10oC. _________

•10g of Ce2(SO4)3 at 10oC_________

•145g of NaNO3 at 80oC. _________

•25g of KNO3 at 60oC. _________

•35g of NaCl at 100oC. _________

•65g of NH4Cl at 80oC. _____________

•12g of NH3 at 90oC. ______________

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The concentration of a solution tells you how much solute that is dissolved in a given amount of solvent (water).The molarity is the concentration of a solution.

Molarity = MolesLiter

1. 2.255 moles of NaCl is dissolved in 4.0 L of water, calculate the molarity.

Molarity =

= 0.56 moles/liter= 0.56 M (Molar)where M means moles per 1 liter

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2. 5.00 g KOH is dissolved in 250. mL of water, calculate the molarity.

Molarity =

= 0.356 M

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Step 1: Step 1: Change mL to L.Change mL to L.

= 0.250 L= 0.250 L

Step 2: Step 2: Calculate Moles Calculate Moles

= 0.0125 moles= 0.0125 moles

Step 3: Step 3: Convert moles to grams.Convert moles to grams.

= = 1.13 g1.13 g

USING MOLARITYUSING MOLARITYUSING MOLARITYUSING MOLARITY

moles = M•Vmoles = M•V

What mass of oxalic acid, What mass of oxalic acid, HH22CC22OO44, is, is

required to make 250. mL of a 0.0500 Mrequired to make 250. mL of a 0.0500 Msolution?solution?

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Molarity PracticeMolarity Practice

• What is the molarity of an aqueous solution containing 40.0 g of glucose (C6H12O6) in 1.5 mL of solution?

• What is the molarity of bleach solution containing 9.5 g of NaOCl per liter of bleach?

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3. How many moles are there in 205. mL of a 0.172 M solution?

0.0353 moles

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4. How many grams NaCl are there in 250.0 mL of 0.500 M solution?

7.31 g

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Dilutions

24Diluting Solutions

Concentrated solutions have a relatively high molarity.Dilute solutions have a relatively low molarity.

M1V1 = M2V2

M1= the initial molarity M2 = the final molarity

V1 = the initial volume V2 = the final volume

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NaCl(aq)

NaCl(aq)

Concentrated solution

Diluted solution

water

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1. 25.0 mL of 0.10 M solution is diluted by adding 75.0 mL of water. Calculate the molarity of the new solution.

M1V1 = M2V2

Initial Solution

M1= 0.10 M M2 = ?

V1 =25.0 mL V2 = 100.0 mL

25.0 mL + 75.0 mL

(0.10 M)(25.0 mL) = M2(100.0 mL)

M2 = 0.025 M

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2. What volume of 0.250 M CoCl2 solution can be diluted to 100.0 mL in order to make a 0.0150 M solution?

Initial Solution

M1V1 = M2V2

M1= 0.250 M M2 = 0.0150 M

V1 = ? V2 = 100.0 mL

(0.250 M) V1 = (0.0150 M)(100.0 mL)

V1 = 6.00 mL

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3. 50.0 mL of 0.500 M CuSO4 solution is diluted to 250.0 mL. Calculate the new concentration and the number of grams CuSO4 in the new solution.

Initial Solution

M1V1 = M2V2M1= 0.500 M M2 = ?

V1 = 50.0 mL V2 = 250.0 mL

(0.500 M)(50.0 mL) = M2(250.0 mL)

M2 = 0.100 M

0.0500 L 0.500 mol 1 L

x x 159.6 g 1 mol

= 3.99 g

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PracticePractice1) If I add 25 mL of water to 125 mL of a 0.15 M NaOH solution, what will the molarity of the diluted solution be?

 

 2) If I add water to 100 mL of a 0.15 M NaOH solution until the final volume is 150 mL, what will the molarity of the diluted solution be?

3) How much 0.05 M HCl solution can be made by diluting 250 mL of 10 M HCl?

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PracticePractice4) I have 345 mL of a 1.5 M NaCl solution. If I boil the water until the volume of the solution is 250 mL, what will the molarity of the solution be?

 

5) How much water would I need to add to 500 mL of a 2.4 M KCl solution to make a 1.0 M solution?

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PracticePractice

6. 734 grams of lithium sulfate are dissolved to make 2500. mL of solution.

7. 6.70 x 10-2 grams of Pb(C2H3O2)4 are dissolved to make 3.50 mL of solution.

8. 83 grams of sodium hydroxide to 750 mL of water.