13.2Colligative Properties

13.2Colligative properties –

13.2Colligative properties – Anytime a solute is dissolved in

a solvent, the properties of the solvent are changed.

13.2Colligative properties – Anytime a solute is dissolved in

a solvent, the properties of the solvent are changed.

These changes are based on the number of particles dissolved, not the type of particle.

13.2Colligative properties – Anytime a solute is dissolved in

a solvent, the properties of the solvent are changed.

These changes are based on the number of particles dissolved, not the type of particle.

The van’t Hoff factor (i) takes the number of particle(s) into account.

i = the number of particles in solution.

NaCl(s) Na1+(aq) + Cl1-(aq) i = 2

C6H12O6 C6H12O6 i = 1

13.2What is an electrolyte? Nonelectrolyte?

13.2Electrolyte – a solute that when dissolved in a solution

produces ions and it will conduct electricity. This could happen through dissociation or ionization.

Nonelectrolyte – a solute that when dissolved in a solution does not produce ions and it will not conduct electricity.

13.2Electrolyte – a solute that when dissolved in a solution

produces ions and it will conduct electricity. This could happen through dissociation or ionization.

Nonelectrolyte – a solute that when dissolved in a solution does not produce ions and it will not conduct electricity.

Are the following electrolytes or nonelectrolytes?

CaCl2C6H12O6

HCl

NH4Cl

13.2Electrolyte – a solute that when dissolved in a solution

produces ions and it will conduct electricity. This could happen through dissociation or ionization.

Nonelectrolyte – a solute that when dissolved in a solution does not produce ions and it will not conduct electricity.

Are the following electrolytes or nonelectrolytes?

CaCl2C6H12O6

HCl

NH4Cl

What would be the van’t Hoff factor for each of the above?

13.2What does nonvolatile mean?

13.2What does nonvolatile mean?

It does not evaporate easily. All of the solutes in this chapter are nonvolatile.

13.21. What happens to the vapor pressure of the solvent,

when a nonvolatile solute is added?

13.21. Reduction of vapor pressure

The higher the number of solute particles present, the lower the vapor pressure above the solution.

13.21. Reduction of vapor pressure

The higher the number of solute particles present, the lower the vapor pressure above the solution.

Because fewer of the solvent particles turn into a gas, the vapor pressure lowers and the liquid phase exists over a larger temperature range.

13.22. What happens to the freezing point of the solvent

when a solute is added?

13.22. What happens to the freezing point of the solvent

when a solute is added?

13.22. Freezing point depression

The higher the number of solute particles dissolved in the solvent, the lower the freezing point.

13.22. Freezing point depression

The higher the number of solute particles dissolved in the solvent, the lower the freezing point.

Each solvent has a unique constant that its freezing point is lowered by for each mole of particles dissolved in a kilogram of solvent. P. 448

13.22. Freezing point depression

The higher the number of solute particles dissolved in the solvent, the lower the freezing point.

Each solvent has a unique constant that its freezing point is lowered by for each mole of particles dissolved in a kilogram of solvent. P. 448

Water’s freezing point goes down by 1.86ºC for every mole of particles dissolved.

13.22. Freezing point depression

The higher the number of solute particles dissolved in the solvent, the lower the freezing point.

Each solvent has a unique constant that its freezing point is lowered by for each mole of particles dissolved in a kilogram of solvent. P. 448

The change in the freezing point can be calculated using:

Δtf = i Kfm

13.23. What happens to the boiling point of a solvent

when a solute is added?

13.23. What happens to the boiling point of a solvent

when a solute is added?

13.23. Boiling point elevation

The higher the number of solute particles dissolved in the solvent, the higher the boiling point.

13.23. Boiling point elevation

The higher the number of solute particles dissolved in the solvent, the higher the boiling point.

Again, each solvent has a unique constant that its boiling point is elevated by for each mole of particles dissolved in a kilogram of solvent. P. 448

Water’s boiling point goes up by 0.51ºC for every mole of particles dissolved.

13.23. Boiling point elevation

The higher the number of solute particles dissolved in the solvent, the higher the boiling point.

Again, each solvent has a unique constant that its boiling point is elevated by for each mole of particles dissolved in a kilogram of solvent. P. 448

The change in the boiling point can be calculated using:

Δtb = i Kbm

13.2Example 1: What will be the new freezing point and

boiling point of an aqueous solution containing 55.0g glycerol, C3H5(OH)3, in 250g of water? Glycerol is a nonvolatile nonelectrolyte.

13.2Example 2: How many grams of glucose, C6H12O6, are

required to lower the freezing point of 150g of H2O by 0.750ºC? Glucose does not dissociate in water.

13.2Example 3: What would be the freezing point of a

solution combining 5.13g of KBr in 255g of water?

13.2What does this mean?

13.2Using percent composition, change in freezing point or

boiling point, and grams used, this can be used in the lab to determine a new compound formed.

13.2Example 4: Lauryl alcohol (a nonelectrolyte) is

obtained from coconut oil and is used to make detergents. A solution of 5.00g of lauryl alcohol in 0.100kg of benzene freezes at 4.1ºC. What is the molar mass of lauryl alcohol?

13.2Example 5: What is the change in boiling point and

freezing point if 3.69 g of K2SO4 is added to 100.0 mL of water?

13.24. What is osmosis? What is osmotic pressure?

13.24. Osmotic Pressure

Osmosis is the movement of a solvent through a semi permeable membrane.

13.24. Osmotic Pressure

Osmosis is the movement of a solvent through a semi permeable membrane. The solvent always moves from an area of high solvent concentration to an area of lower solvent concentration.

13.24. Osmotic Pressure

Osmosis is the movement of a solvent through a semi permeable membrane. The solvent always moves from an area of high solvent concentration to an area of lower solvent concentration.

Osmotic pressure is the pressure that must be applied to stop osmosis from happening.

13.24. Osmotic Pressure

Osmosis is the movement of a solvent through a semi permeable membrane. The solvent always moves from an area of high solvent concentration to an area of lower solvent concentration.

Osmotic pressure is the pressure that must be applied to stop osmosis from happening.

The higher the number of solute particles dissolved in the solvent, the higher the osmotic pressure which must be applied to stop osmosis.

Tube is filled with water on one side and sucrose solution on the other.

Water particles move to the right. As the sucrose solution increases in height it exerts a pressure against the water moving.

If extra pressure is applied to the sucrose side, the water can be forced to move “backwards”.

REVERSE OSMOSIS FILTRATION

TIME RELEASE DRUG CAPSULE

CHAPTER 13 TEST15 multiple choice (4 points each)5 colligative property questions (5 points each)5 writing net ionic equations (3 points each)1 extra credit (5 points)

Dissociation vs ionizationWriting equations for both

Precipitation reactionsWriting net ionic equationsPredicting precipitatesLabeling spectator ions

Electrolytes vs nonelectrolytesWeak vs strong electrolytes

4 colligative propertiesVapor pressure reductionBoiling point elevationFreezing point depressionOsmotic pressure

Calculate changes in boiling point or freezing pointCalculate molar massCalculate molality