# Combined Gas Law

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1. May 4, 2015

### CheesyPeeps

I am studying National 5 physics, and my exam is tomorrow. I need some last-minute help.
I'm struggling a little bit with the combined gas law, P1V1/T1 = P2V2/T2, and I'm not sure why.
It would help me a lot if you could show step-by-step how the formula is used.
Thanks for your time, it's very much appreciated.

2. May 4, 2015

### Staff: Mentor

Where exactly are you having problems with it?

3. May 4, 2015

### CheesyPeeps

That's the problem: I'm not sure where things are going wrong. I think it may be when I substitute in the values and then have to rearrange the equation, which seems strange because usually rearranging equations is the easiest part!

4. May 4, 2015

### Staff: Mentor

I'd suggest finding a homework question and posting it in the homework forums, that way the homework helpers can walk you through it and find out where you're having trouble.

5. May 4, 2015

### CheesyPeeps

Okay!
Thanks a lot for your time.

6. May 4, 2015

### Staff: Mentor

I'm sure I'll stop by your thread later, as we are studying the gas laws in class this week.

7. May 4, 2015

### CheesyPeeps

Update: I did some exam-style questions on it and I've got it now! I think it was a mixture of me overcomplicating it and occasionally forgetting to convert the temperature into kelvin

8. May 5, 2015

### Staff: Mentor

Yes, I just clarified this with my instructor tonight. Makes sense, otherwise you end up with negative numbers when your temperature goes below zero!