Chapter 9, Problem 9.31P

Interpretation Introduction

(a)

Interpretation:

The PV work needs to be calculated in kJ. The direction of flow of work energy needs to be determined.

Concept introduction:

The PV work can be calculated as follows:

$W=-P_{\text{external}}\Delta V$

Here, $P_{\text{external}}$ is external pressure and $\Delta V$ is change in volume.

Interpretation Introduction

(b)

Interpretation:

The change in internal energy for the combustion of 1 mol of ethanol needs to be determined.

Concept introduction:

The enthalpy is sum of types of internal energies.

Thus,

$\Delta H=\Delta E+P\Delta V$

Here, $\Delta E$ is change in internal energy.