# Partial Pressure Problem

1. Jan 16, 2008

### elitespart

1. Assume that two cylinders at 27° C are connected by a closed stopcock(valve) system. The right-hand cylinder contains 2.4L of hydrogen at 0.600 atm; the left cylinder is larger and contains 6.8 L of helium at 1.40 atm.
a) How many moles of each gas are present?
b) What is the total pressure when the valve is open?
c) Determine the partial pressure of these two gases at 27° C when the stopcock is opened.

2. Relevant equations: PV=nRT and Dalton's partial pressure equation.

3. I got the moles of each gas for part a. For b and c, do I just add up the the individual volumes to get the total volume when the valve is opened? For some reason I'm just thinking that there is a tube connecting the two cylinders which would add additional volume. Thanks.

2. Jan 17, 2008

### chemisttree

Neglect the tube volume.