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### application of PV=nRT

Posted: **Sat Jan 13, 2018 2:15 pm**

by **Peter Dis1G**

I know this formula is for the ideal gas. So when there is a reaction related to gas, say combustion reaction, and question tells us to find the internal energy, is that the correct way of applying? Thanks.

### Re: application of PV=nRT

Posted: **Sat Jan 13, 2018 2:24 pm**

by **Curtis Tam 1J**

I think heat should still be calculated with q=mc(deltaT). The only difference with these ideal gases is that the heat capacities could be any of those found on page 281. I'm not entirely sure if this is what you're referring to though.

### Re: application of PV=nRT

Posted: **Sat Jan 13, 2018 2:37 pm**

by **Peter Dis1G**

Sorry I forgot to add, I am referring to reaction enthalpies.

### Re: application of PV=nRT

Posted: **Sun Jan 14, 2018 5:08 pm**

by **Anh Nguyen 2A**

You can calculate reaction enthalpies (ΔH) by using standard formulation enthalpies.

Change in internal energy is ΔU.

∆U=ΔH-Δn(gas)RT or you can replace Δn(gas)RT with PΔV.