Chapter 5, Problem 5.18NP

Interpretation Introduction

Interpretation: The value of q, $\Delta U$ and $\Delta H$ needs to be determined for each step in the cycle and also, for the total cycle.

Concept introduction:

The work done can be calculated using the two equations depending on the conditions.

  $w=-nRT\ln \frac{V_f}{V_i}$

Here, n is number of moles, R is Universal gas constant, T is temperature, $V_f$ is final volume and $V_i$ is initial volume.

Also,

  $w=n{C}_{V,m}\left(T_f-T_i\right)$

For the isothermal process, change in enthalpy can be calculated as follows:

  $\Delta H=C_{P,m}n\Delta T$

Here, $C_{P,m}$ is molar heat capacity at constant pressure.

Also, the change in internal energy as follows:

  $\Delta U=C_{V,m}n\Delta T$

Here, $C_{V,m}$ is molar heat capacity at constant volume.