Another Dalton Question (Partial Pressure)?

Question

1. A 54.0 mL sample of oxygen is collected over water at 23C at 770.0 torr pressure. What is the volume of the dry gas at STP? (Vapor pressure of water at 23C=21.1 torr)

2. THe partial pressure of F2 in a mixutre of gases where the total pressure is 1.00 atm is 300. torr. What is the mole fraction of F2?

Answer 1

1. Start by subtracting 21.1 from 770. Then use pV = nRT.

2. Divide 300 by 760.