Chapter 13, Problem 88IAE

Interpretation Introduction

Interpretation:

The temperature at which the equilibrium pressure of water vapor is 75 torr needs to be determined.

Concept introduction:

The Gibb’s equation of thermodynamic proposed a relation between $\text{ΔS}$, $\text{ΔH}$ and $\text{ΔG}$ with temperature. The mathematical expression of Gibb’s equation can be written as

$\text{ΔrG}°\text{ = ΔrH}°\text{ - TΔrS}°$

$\text{ΔrG}°$, $\text{ ΔrH}°$ and $\text{ΔrS}°$ can be calculated with help of given equation:

$\begin{array}{l}\text{ΔrH° = ΔrH°(product) - ΔrH°(reactant) }\\ \text{ΔrS° = ΔrS°(product) - ΔrS°(reactant) }\\ \text{ΔrG° = ΔrG°(product) - ΔrG°(reactant) }\end{array}$

With the help of this equation one can predict the change in $\text{ΔS}$, $\text{ΔH}$ and $\text{ΔG}$. ${\text{K}}_{\text{p}}$ or $\text{Kc}$ are the equilibrium constants for the reaction which are ratio of gaseous and aqueous products and reactant molecules. The relation between equilibrium constant and $\Delta \text{rG}°$ can be written as:

$\text{ΔrG° = - 2}\text{.303 RT log K}$