Colligative properties

Ethlene glycol-antifreeze

Changes where:1. Boiling point elevation2. Freezing point depression3. Osmotic pressure4. Reduction of vapor pressure

Salty tears

This frog is frozen but is still alive because the water in it did not turn into ice crystals, which would have ruptured the cells in its body.

Glucose and glycerin in its blood and cells prevent water from freezing. In other words, glucose and glycerin get in the way of water trying to organize itself to create ice crystals. Also, their presence created disorder in the water. So water as to overcome that disorder in order to arrange itself neatly into ice crystals.

Freeze tolerance

1. Effect of sucrose on the freezing and boiling point of water

30.0 gof table sugar, sucrose (non-electrolyte), C12H22O11, is added to 30.0 g of H2O(Kf=-1.86oC/Kg; Kb= 0.52oC/Kg)

Freezing point: ΔT= -5.44oCBoiling point: ΔT= 1.52oC

2. If the addition of an unknown amount of ethylene glycol to 150 g og water dropped the freezing point of the solution by -1.86, what mass of ethylene glycol was used?

Mass of solute: 9.3 g

3. A solution of 10.0 g of NaCl is added to 100.0 g of water (Kb= 0.52oC/Kg) in an attempt to elevate the boiling point. What is the new boiling point of the solution?

van’t Hoff factor: 2 ΔT= 1.78oCBoiling point: 101.78oC

4. A physician studying hemoglobin dissolves 21.5 mg of the protein in water at 5.0oC to make 1.5 ml of solution in order to measure its osmotic pressure. At equilibrium, the solution has an osmotic pressure of 3.61 torr. What is the molar mass of the hemoglobin?

M= 6.89 x 104 g/mol

6. A solution is prepared by dissolving 3.423 g of aluminium sulfate in 25.00 mL water at 45.0 °C. At 45.0 °C, the vapor pressure of water is 26.47 torr and its density is 0.985 g cm-3. What is the vapor pressure of the solution?

Psolution=(0.98558) (26.47 torr)Psolution= 26.09 torr

5. 210.0 g of the nonvolatile solute sucrose (C12H22O11) is added to 485.0 g of water at 25.0 °C. What will be the pressure of the water vapor over this solution? (The vapor pressure of pure water is 23.8 torr at 25.0 °C.)

Psolution=(0.9772) (23.8 torr)Psolution= 23.3 torr

The sugar used in the U.S. is normally fructose. The ingredients say 39 grams of sugar. Since water is the solvent, the Kf is 1.86°C·kg/mol. 12 oz is 355 mL.So the water present is close to 355 grams or 0.355 kg. The molar mass of fructose is 180.16 g/mol.1. Problem: How many degrees Celsius does the sugar reduce the freezing point of water in the can?ΔT = Kf msolute

Observation: Why Diet Coke is called “Diet Coke”?A can of Diet Coke could explode from freezing but the regular Coke in can will not freeze and therefore will not explode. Why?Regular coke has about 39 grams of sugar dissolved in it. Diet Coke has only about 0.1 gram of Aspartame sweetener in it. The 39 grams of sugar interfered with the water trying to freeze. So the freezing point of regular Coke was lower than that of Diet Coke. Diet Coke's freezing point is basically the same as water since very little is dissolved in Diet Coke.