# Homework Help: Expanding monotomic gas

1. May 10, 2005

### ~angel~

We start with 5.00 moles of an ideal monatomic gas with an initial temperature of 127C. The gas expands and, in the process, absorbs an amount of heat equal to 1220 J and does an amount of work equal to 2180 J.

I fouind out the change in U, which is -960. I'm just not sure how to calculate Q. Any help would be greatly appreciated.

2. May 11, 2005

### OlderDan

I don't understand the question. Why isn't Q the heat absorbed that you were given?

3. May 11, 2005

### ~angel~

Sorry, I forgot to ask the question (I just copied and pasted it).

The question is:

What is the final temperature T_final of the gas?
Use R = 8.3145 J/mol/K for the ideal gas constant.

4. May 11, 2005

### jdstokes

Use $Q = \Delta U + W$.

5. May 11, 2005

### OlderDan

You should be able to calculate the initial internal energy of the gas, given that you know the termperature, how much gas you have, and that it is ideal monatomic. You know how much internal energy was lost in the process, so you know the final internal energy, from which you can calculate the final temperature. Look for the discussion in your text or notes about how internal energy in an ideal gas is distributed.