# Problem with ideal gas pressure

1. Aug 13, 2008

### ttkingdom

1. The problem statement, all variables and given/known data

Diagram here:
http://img99.imageshack.us/img99/7189/systemgk9.jpg [Broken]

Two bulbs, A of volume 100cm3 and B of volume 50cm3 , are connected to a three way tap T which enables them to be filled with gas or evacuated. The volume of the tubes may be neglected.
Initially bulb A is filled with an ideal gas at 10oC to a pressure of 3.0 x 105 Pa. Bulb B is filled with an ideal gas at 100oC to a pressure of 1.0 x 105 Pa. The two bulbs are connected with A maintained at 10oC and B at 100oC. Calculate the pressure at equilibrium.

2. Relevant equations
PV = nRT

3. The attempt at a solution

I have the total Volume, total n but I can't find the final temperature of the system.

Initially you have $P_A V_A=n_A R T_A$ and $P_B V_B=n_B R T_B$. You can figure out all of those numbers, right? Finally you have a new pressure $P$ and new molar numbers $n'_A$ and $n'_B$, three unknowns. So you need three equations to find them. You have two PV=nRT equations in the final state (one for each bulb) and $n_A+n_B=n'_A+n'_B$.