# Thermodynamics Problem

1. Feb 6, 2009

### Robershky

1. The problem statement, all variables and given/known data

When 1380 J of heat are added to one mole of an ideal monatomic gas, its temperature increases from 272 K to 275 K. Find the work done by the gas during this process.

2. Relevant equations

I assume $$\Delta$$U = Q - W is the formula to use. But for some reason I'm just confused.

3. The attempt at a solution

I tried using 1380 = 275 - W, and got -1105. But that is not the correct answer.

2. Feb 6, 2009

### Mapes

Can you relate $\Delta U$ to $\Delta T$?

3. Feb 6, 2009

### Robershky

That's the problem, I don't understand how they relate. Is there a conversion from Kelvin to Joules? Or do I just use 3K = 1380J - W?

4. Feb 6, 2009

### Mapes

Check your book, notes, or reference for an equation of the internal energy (U) of an ideal gas.

5. Feb 6, 2009

### Brian_C

Internal energy increases with increasing temperature, but the exact relation will depend on the type of gas. You should figure out how many degrees of freedom are present in a monatomic gas, then use equipartition of energy to express the internal energy as a function of temperature.

6. Feb 7, 2009

### Andrew Mason

You are given Q and you can determine $\Delta U = nC_v\Delta T$. So it is just a matter of applying the first law to determine W.

AM