[shell52080]

Pchem isn't my thing. I'm having trouble with the following problem:

When 3 mol O2 is heated at a constant pressure of 3.25 atm, the temp increases from 260K to 285K. Given that the molar hear capacity of O2 at constant pressure is 29.4JK^-1mol^-1, calculate q, delta U and delta H.

I found delta H to be 1323 J which is also q. Let me know if that's wrong.

I'm having trouble with the delta U. I found V1 and V2 using Van der Waal's equation. V1=19.6L and V2=21.51L

I then used the equation:

delta H= delta U + p(delta V)

I found delta U to be -61.6kJ. This does not seem right to me. Does anyone know what I'm doing wrong? For a perfect gas delta H is equal to delta U at constant pressure and volume. Is that true for real gases too?

Thanks!