Adiabatic expansion of an ideal gas

[Elvis 123456789]

Homework Statement

An ideal monatomic gas has initial pressure Po and occupies initial volume Vo. The gas undergoes an adiabatic expansion in which the volume is doubled. Calculate in terms of Po and Vo

a) the final pressure of the gas

b) the change in its enthalpy during the expansion

Homework Equations

I posted two attachments with my attempted solutions. All the relevant equations are there. Just posting to see if anyone can spot anything wrong with my solutions. I feel fairly confident about part a, but not so much about part b.

The Attempt at a Solution

 

[TSny]

I feel fairly confident about part a, but not so much about part b.

In part b you treated T as constant during the process.

 

[Elvis 123456789]

In part b you treated T as constant during the process.

Yeah that's the part I felt most uncomfortable about. Is this the right approach then, or do I have to go about it another way?

 

[ehild]

Yeah that's the part I felt most uncomfortable about. Is this the right approach then, or do I have to go about it another way?

Using the equation pV^γ=const for adiabatic processes?

 

[Elvis 123456789]

Using the equation pV^γ=const for adiabatic processes?

yes that's it! thanks :)