# Energy required to heat a house

1. Sep 25, 2007

### physicnow

I have an problem that can not solve, any help would greatly appreciated.

A house has well-insulated walls.It contains a volume of 100m3 of air at 300K. Calculate the energy required to increase the temperature of this diatomic gas by 2 degree celsius. Assume it is heating at constant pressure and use Cp=7R/2.

2. Sep 25, 2007

### Dick

What's stopping YOU from solving it? You've got a heat capacity, you've got a temp difference. What more could you want? Oh, yeah, maybe the number of moles?

3. Sep 26, 2007

### physicnow

Thanks Dick, that's problem I couldn't solve for the number of moles. I know the formular

PV=nRT, the problem here, how can I find P & R? P is constant? T is 275 right? or Delta T is 275, make me confuse.... the answer is:118KJ,236KJ,354KJ,472KJ

4. Sep 26, 2007

### Dick

They are talking about a 'house'. I think you can assume the pressure is 1 atmosphere. You don't 'find' R. It's a constant. You look it up. The problem you quoted says T=300K.

5. Sep 26, 2007

### physicnow

Hi Dick,

I wonder "Calculate the energy required to increase the temperature of this diatomic gas by 2 degree celsius. Assume it is heating at constant pressure and use Cp=7R/2."

They asked for the energy required to increase the temperature of this diatomis gas by 2 degree celsius. I got stuck in here.

6. Sep 26, 2007

### Dick

(Change in energy)=(Heat capacity)*(change in temperature)*(amount of stuff). You are already given two quantities on the right side - you just need to find the amount of stuff. Number of moles, remember?