# Colligative Properties of Nonelectrolyte Solutions

1. Nov 24, 2005

### erik-the-red

How many grams of sucrose ($$C_{12} H_{22} O_{11}$$) must be added to 552 g of water to give a solution with a vapor pressure of 2.0 mmHg less than that of pure water at $$20 ^ \circ$$ C? The vapor pressure of pure water at $$20 ^ \circ$$ C is 17.5 mmHg.

This is one of many similar types of problems in Chemistry (7th ed.) by Raymond Chang.

I don't know how to start this. Does it involve Raoult's Law?

2. Nov 24, 2005

### Gokul43201

Staff Emeritus
Yes, (in the limit of a dilute solution) you can use Raoult's Law.

PS : Next time, such questions go in the appropriate section of the Homework/Coursework forum. And before posting there, please read the rules for posting (also found in the second line of my sig.)