ChemistryName :

Worksheet : Ch. 17-18 ; Obj. 35-39 problemsDate :

  1. What is the mole fraction of solute and solvent of a solution made from dissolving1.6 grams of glucose (C6H12O6) in 100.0 grams of water?
  1. What are the mole fractions of a solution formed by dissolving 15.0 grams of sucrose (C12H22O11) in 355 grams of water?
  1. What is the freezing point of a solution made from dissolving 5.50 grams of glucose in 200.0 grams of water (Kf = 1.86 ºC)?
  1. What is the boiling point of a solution made by dissolving 85.0 grams of sucrose in 500.0 grams of water? (Kb = .512 ºC/m)
  1. What is the boiling point of a solution made by dissolving 25.0 grams of sodium chloride in 300.0 grams of water?
  1. What is the boiling point of a solution made by dissolving 15.0 grams of magnesium chloride in 400.0 grams of water?

7. Calculate the freezing point and boiling point of an antifreeze solution that is 40.0% by mass of ethylene glycol (HOCH2CH2OH, FW= 62.08 g/mol) in water. Ethylene glycol is a nonelectrolyte. (Kf for water = 1.86 ºC/m)(Hint : Assume you have 100. grams of the solution).

8. A solution contains 35.5 grams of a nonvolatile, nonelectrolyte solute in 400.0 grams of water. If the solution freezes at -1.20 ºC, what is the molecular mass of the solute?

9. A solution contains 155 grams of a nonvolatile, nonelectrolyte solute in 650.0 grams of water. If the solution boils at 101.8 ºC at 1 atm, what is the molecular mass of the solute?

10. Calculate the freezing-point depression of an aqueous solution containing 1.0 g/L of a protein (molar mass = 9.0 x 104 g/mol) if the density of the solution is 1.0 g/cm3.(Hint : calculate kg of solvent (water) by subtracting mass of solute from total mass).

Answers : 1. Xgl = .0016 ; XH2O = .9984 2. Xsu = .00222 ; XH2O = . 998 3. -0.284 ºC 4. 100.254 ºC 5. 101.46 ºC 6. 100.605 ºC 7. F. pt. = -19.9 ºC, B. pt. = 105.48 ºC 8. 138 g/mol 9. 67.8 g/mol 10. 2.1 x 10-5 ºC