** SOLUTIONS**

Solutions are often called ______________________________; no matter where you
sample them, they have the same ______________________ but they are composed of
____________ or more materials.

I. Basic Terms

________________

Substance __________ ___________________

Can be individual _______________, ____________________ or ___________

Won’t ____________________

Can’t be ____________________

________________________ light (but may absorb some colors)

SOLVENT

Substance ____________________ the _________________

Two types:

1. _________________: _____________ and those substances

______________with water

ex. alcohol, ammonia

2. ________________________: __________________ with ____________

ex. oil, paint thinner, mineral spirits, dry cleaning fluids

II. Types of Solutions

SOLUTE SOLVENT EXAMPLES

Solid ______________ salt in water

iodine in alcohol

Solid _____________ alloys such as:

brass (Cu/Zn)

steel (Fe/Cr/C)

14K gold (Cu/Au)

Liquid Liquid alcohol in water

glycols in water

Solid metal tooth fillings

(Hg in Ag)

__________ Liquid Oxygen in water

soda = CO2 in water

“carbonated”

Gas Gas Air

III. Degrees of Solubility

How much solute is dissolved in the solvent?

______________________ - could hold more solute

____________________ - holding as much solute as is possible at this temperature

______________________ - holding more solute than is normal at a certain
temperature (do this by heating the saturated solution to get extra solute
dissolved then carefully cool it)

IV. Factors that Influence the Rate of Dissolving

A. _______________________

- important for ____________ and ____________

ex. sugar: __________ __________ ___________

rate of

dissolving: __________--------->__________ -----------> __________

Crushing it exposes more ______________________ for the ____________ to attack.

B. ____________________

- affects only ______________ ex. can of soda

C. _____________________

Suppose we make five ___________________ solutions using the same solute in 100
mL of water, but heat the water each time. We find that __________ dissolves as
the water gets hotter.

From this data we construct a _________________ _______________

Any solution on the curve is _________________

What is the solubility at 60oC? ___________________

A solution at 60oC that contains 80 g is _______________________: any solution
________________ the line is ________________________

A solution at 60oC that contains 2 grams is ____________________

IV. Concentrations of Solutions

A. Molarity

Molarity =

Example 1: Suppose you have 1.00 mol of sucrose (or about 342.3 grams) and you
mix it into some water. It dissolves and makes sugar water. You keep adding
water, dissolving and stirring until all the solid is gone. There is exactly 1
liter of solution.

What is the molarity of this solution?

Answer:

Molarity =

Example 2: Suppose you had 2.00 moles of solute dissolved into 1.00 L of
solution. What is the molarity?

Answer:

Molarity =

Example 3: What is the molarity when 0.75 mol is dissolved in 2.50 L of
solution?

Answer:

Molarity =

Example 4: Suppose you had 58.44 grams of NaCl and you dissolved it in exactly
2.00 L of solution. What is the molarity of the solution?

Answer:

Example 5: Calculate the molarity of 25.0 grams of KBr dissolved in 750.0 mL.

Example 6: 80.0 grams of glucose (C6H12O6; molar mass = 180.0 g/mol) is
dissolved in enough water to make 1.00 L of solution. What is its molarity?

Practice Problems

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

2) 100.0 grams of sucrose is dissolved in 1.50 L of solution. What is the
molarity?

3) 49.8 grams of KI is dissolved in enough water to make 1.00 L of solution.
What is the molarity?

B. Molality

Molality =

Example 1: Suppose you have 1.00 mole of sucrose (about 342.3 grams) and you mix
it with exactly 1.00 liter of water. What is the molality?

Example 2: Suppose you had 2.00 mol of solute dissolved into 1.00 L of solvent.
What’s the molality?

Example 3: What is the molality when 0.75 mol is dissolved in 2.50 L of solvent?

Example 4: Suppose you had 58.4 grams of NaCl and you dissolve it in exactly
2.00 kg of pure water. What would the molality of this solution be?

Example 5: Calculate the molality of 25.0 grams of KBr dissolved in 750.0 mL of
pure water.

Example 6: 80.0 grams of glucose is dissolved in 1.00 kg of water. Calculate the
molality.

Practice Problems

1) Calculate the molality when 75.0 grams of MgCl2 is dissolved in 500.0 grams
of solvent.

2) 100.0 grams of sucrose is dissolved in 1.50 L of water. What is the

molality?

3) 49.8 grams of KI is dissolved in 1.00 kg of solvent. What is the molality?

V. Colligative Properties

______________________ - a property of a solution that depends on the number of
solute particles

A. Boiling Point Elevation

1. Fact: A solution will boil at a _______________ temperature than a pure
solvent.

Why? The vapor pressure of a solution is ____________ than that of the pure
solvent at any temperature. A _____________ temperature is needed to raise the
solution’s vapor pressure to equal external pressure.

2. Equation

Tb = i Kb m

a. Tb = change in the boiling point (units: oC)

if the Tb is the normal boiling point of the pure solvent

then, Tb(solution) = Tb + Tb

b. i = van’t Hoff factor (no units)

the change in boiling point ( Tb) is directly related to the

number of solute particles that are in the solution

for sugar: C12H22O11 (s) --------> C12H22O11 (aq)

* substances that do not dissociate in solution, like sugar, have

i = _______

for NaCl: NaCl (s) -------> Na+ (aq) + Cl- (aq)

* substances which dissociate into two ions, like NaCl, KCl, and

NaOH, have i = ______

for MgCl2: MgCl2 (s) ------> Mg2+ (aq) + 2 Cl- (aq)

* substances which dissociate into three ions, like MgCl2 and

Mg(OH)2 have i = ______

c. Kb is the molal boiling point elevation constant (units: oC/m or

oC . mol/kg)

every solvent has a unique Kb

ex. Kb (H2O) = 0.52 oC/m

d. m is the molality

Examples:

1) Which solution has a higher boiling point, 1 mol of Al(NO3)3 in 1000 g of
water or 1.00 mol of KCl in 1000 g of water? Explain.

2) What is the boiling point of a 1.50 m NaCl solution?

3) What is the boiling point of each solution?

a) 0.50 mol glucose in 1000 g of water

b) 1.50 mol NaCl in 1000 g of water

B. Freezing Point depression

1. Fact: A solution will freeze at a _____________ temperature than the pure
solvent.

Why? The vapor pressure of a solution is ___________ than that of the solvent at
any temperature, the solution freezes at a temperature than the solvent.

2. Equation

Tf = i Kf m

Tf = change in freeing point

so... Tf (solution) = Tf (solution) - Tf

i = van’t Hoff factor

Kf = molal freezing point depression constant (units: oC/m)

m = molality

Example:

1) What is the freezing point of each solution?

a) 1.40 mol Na2SO4 in 1750 g of water

b) 0.60 mol MgSO4 in 100 g of water

2) Determine the freezing points of each 0.20 m solution:

a) K2SO4

b) CsNO3

c) Al(NO3)3

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