# Homework Help: Final pressure

1. Dec 6, 2011

### gwiber

1. The valve between a 5 liter tank in which the gas pressure is 911.925 kPa and a 10 liter tank containing gas at 4560 torr is turned open and equilibrium is established at constant temperature. What is the final pressure in the two tanks in atmospheres?

2. PV = nRT

3. The attempt at a solution

2. Dec 6, 2011

### ptolema

This is solved using weighted averages. The final pressure in the 2 tanks is the weighted average of the initial pressure. The weights come from the volumes: V1/(V1+V2) for tank 1, V2/(V1+V2) for tank 2.