What are the final pressure for the gas?

[itryphysics]

Homework Statement

A 1.00-mol sample of an ideal diatomic gas, originally at 1.00 atm and 15 celcius, expands adiabatically to 2.00 times its initial volume.

What are the final pressure for the gas? (Assume no molecular vibration.)
What are the final temperature for the gas?

Homework Equations

lnP + gamma lnV = constant

The Attempt at a Solution

I don't know how to use this equation and its the only one given in the adiabatic expansion section of my book. Can someone please guide me through. Thanks!

 

[Confundo]

http://en.wikipedia.org/wiki/Adiabatic_process

 

[itryphysics]

I was able to solve for the final pressure. can you please show me how to find the final temperature. Thanks!

 

[Confundo]

Just use the ideal gas equation again. You've know V_2 = 2V_1

 

[itryphysics]

but the no numerical value for volume is given...

 

[Confundo]

Use the ideal gas equation to find V_1

 

[Confundo]

You could also use the equation involving P, T and gamma. Using the ideal gas equation afterwards is a good check though.