Finding the change in pressure and entropy of a quasistatic adiabatic process

1. Sep 19, 2010

rg2004

1. The problem statement, all variables and given/known data
Suppose that one mole of an ideal gas expands in a quasi-static adiabatic process from P1 = 1 Pa and V1 = 1m3 to V2 = 8m3. What is the change in the pressure and the entropy of the gas?

2. Relevant equations

PV$$\gamma$$=constant

3. The attempt at a solution
I can't come up with a second equation that doesn't introduce another unknown. I've been working on thermodynamics for the past two days almost non-stop and I'm drained. Any help would be nice. thanks.

2. Sep 19, 2010

rg2004

perhaps I am supposed to assume that the gas is monoatomic? My textbook is vague and its not clear to me whether all ideal gasses are considered monoatomic.

this is what i found:

$$\gamma$$= 5/3 (ideal monatomic gas).