# Physics: Expansion at constant pressure

1. Apr 8, 2012

### FutureE'neer

An unknown number of moles of an ideal monoatomic gas expand reversibly from Vi = 2.30 m3 to Vf = 3.10 m3, at a constant pressure of 1.71 atm and an initial temperature of 300 K.
Find the number of moles of gas.
Find the final temperature of the gas K.
Calculate the work done by the gas.

I cannot find the number of moles and I don't know what I'm doing wrong.
I'm using PV=nRT
Converting the pressure in atm to N/m^2 and m^3 to L. I'm using the initial volume for V, 8.315 for R and the initial temp in K and solving for n. I keep getting the same answer and it is coming up wrong. Please help!

2. Apr 8, 2012

### 256bits

Keywords are "ideal monoatomic gas expand reversibly "
What does that mean to you?

3. Apr 8, 2012

### FutureE'neer

that's how much it fluctuate's?

4. Apr 8, 2012

### nasu

Can you show what you did (and how do you know is wrong)?
The method (using equation of state for initial state) seems OK.

5. Apr 9, 2012

### Emilyjoint

Don't change m^3 to litres