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The heat capacity of liquid water is 4.18 J/g middot degree C and the heat of va

ID: 1073437 • Letter: T

Question

The heat capacity of liquid water is 4.18 J/g middot degree C and the heat of vaporization is 40.7 kJ/mol. How many kilojoules of heat must be provided to convert 1.00 g of liquid water at 67 degree C into 1.00 g of steam at 100 degree C? 22.7 kJ 40.8 kJ 2.2 kJ 2, 400 J 40.8 J Calculate the molality of a 20.0% by mass ammonium sulfate (NH_4)_2SO_4 solution. The density of the solution is 1.117 g/mL. 0.150 m 1.51 m 1.70 m 1.89 m 2.10 m Consider a solution made from a nonvolatile solute and a volatile solvent. Which statement is true? The vapor pressure of the solution is always greater than the vapor pressure of the pure solvent. The boiling point of the solution is always greater than the boiling point of the pure solvent. The freezing point of the solution is always greater than the frying point of the pure solvent.

Explanation / Answer

5. Heat required = 1 x 4.18 x (100 - 67) + 1 x 40.7 x 10^3/18

                           = 2,400 J

Answer : D) 2,400 J

6. Molality = moles of solute/kg of solvent

moles = 20 g/132.14 g/mol = 0.151 mol

mass of solvent = (100 - 20)/1000 = 0.08 kg

molality = 0.151/0.08 = 1.89 m

Answer : D) 1.89 m

7. For a solution of non-volatile solute and volaile solvent, the true statement would be,

B) the boiling point of solution is always greater than the boiling point of pure solvent