Question

1. As the intermolecular forces between molecules increase in magnitude, do you expect each of the following to increase, decrease or remain the same?

My answers:

Viscosity: increase
Boiling point: increase
Vapor pressure: decrease
Surface tension: increase
Heat of Vapirization: increase


2. The melting point of compound X is 34 degrees Celsius at 1.00 atm pressure. The temperature of its triple point is 45 degrees Celsius. It may be helpful to sketch a phase diagram.

A) Compound X expands when it freezes
B) Compound X contracts when it freezes
C) Compound X's volume does not change when frozen

My answer: A


3. Growing up in a dry climate,we cooled the house using evaporative cooling. Like air, other things can be cooled using evaporation. How many grams of water can be cooled from 35 degrees C to 20 C by the evaporation of 65 g of water? The heat of vaporization of water in this temperature range is 43 kJ/mol. The specific heat of water is 4.18 J/g C.

My answer : 1.708g