## 4.7b

$w=-P\Delta V$
and
$w=-\int_{V_{1}}^{V_{2}}PdV=-nRTln\frac{V_{2}}{V_{1}}$

Alicia Lin 2F
Posts: 83
Joined: Wed Sep 18, 2019 12:17 am

### 4.7b

(a) Calculate the work that must be done against the atmosphere for the expansion of the gaseous products in the combustion of 1.00mol C6H6 (l) at 25°C and 1.00 bar. (b) Using data in Appendix 2A, calculate the standard enthalpy of the reaction. (c) Calculate the change in internal energy, ΔU, of the system.

For part b, I took the sum of the standard enthalpies of formations for the products and subtracted the sum of the standard enthalpies for reactants. I got -3135.52 kJ/mol. The book says the answer is -3267.5 kJ/mol. Am I missing a step? Or did I go about this problem wrong?

Brian_Ho_2B
Posts: 221
Joined: Fri Aug 09, 2019 12:16 am

### Re: 4.7b

There is a chart in the book that lists the standard reaction enthalpies of different combustion reactions. On a side note, how did you do part A of 4.7? I've been stuck on why the answer is 3.72 kJ