Ideal Gas Law, Pressure equilibrium

[pengy44]

Ok so I just need help with clarifying in how I should attempt to solve this problem. There's two question involving the same information. I've solved the first question but need help with setting up the second one.

Here is the problem:
Two containers, A and B are filled with argon. The containers are connected by a pipe of negligible volume, but initially a valve in this pipe is CLOSED. Here are the given information:

Temperature of A and B = 300.15 Kelvin
Volume(A) = 0.05 cubic meters
Volume(B) = 0.15 cubic meters
Pressure in A and B = 101326.5 Pascals


Here is a rough drawing of the picture
__________
___ l l
l l____l B l
l A ____ l
l___l l_________l

Questions 1:
With the valve still shut, A is now heated up to 400.15 Kelvin while the temperature of B maintains at 300.15 Kelvin. The volumes remains the same. Calculate the pressure in A at 400.15 Kelvin.

(For this question, I manage to find the pressure at 400.15 Kelvin which is 135085.1 Pascal by using the equation (PV)/T=(PV)/T. So we can skip this question.)


Question 2:
The valve in the connecting tube is now OPENED while A and B are each maintained at 400.15 Kelvin and 300.15 Kelvin, respectively. What will the final (equilibrium) pressure of the system?

(I'm having problems with this question, I'm not sure on how to set it up. I was thinking of finding the new pressure for container A and then the pressure for container B. Then just average them for the equilibrium.)



It seems like there's a lot of information here but really I just need help with how to begin solving question 2. Thanks!

 

[Andrew Mason]

Ok so I just need help with clarifying in how I should attempt to solve this problem. There's two question involving the same information. I've solved the first question but need help with setting up the second one.

Here is the problem:
Two containers, A and B are filled with argon. The containers are connected by a pipe of negligible volume, but initially a valve in this pipe is CLOSED. Here are the given information:

Temperature of A and B = 300.15 Kelvin
Volume(A) = 0.05 cubic meters
Volume(B) = 0.15 cubic meters
Pressure in A and B = 101326.5 Pascals

...
Question 2:
The valve in the connecting tube is now OPENED while A and B are each maintained at 400.15 Kelvin and 300.15 Kelvin, respectively. What will the final (equilibrium) pressure of the system?

(I'm having problems with this question, I'm not sure on how to set it up. I was thinking of finding the new pressure for container A and then the pressure for container B. Then just average them for the equilibrium.)

First you have to determine how many moles are on each side initially and then determine how many moles there must be on each side in order to equalize pressure. That last part is the tricky one.

Write out the expression for the number of moles of gas on each side initially. What is the total amount of gas? Does that change?

Write out the expression for the total amount of gas in the system after the pipe opens and pressure equalizes by writing out the expression for the n for each side and then adding them together.

That will give you an expression containing only one unknown, P. (You know n_total, Va, Vb, Ta, Tb).

AM