Chapter 15, Problem 15.70SP

Interpretation Introduction

Interpretation:

The value of K_p and K_c at 25 ⁰ C for the equilibrium ${\text{H}}_2\text{O(l) }\rightleftharpoons {\text{ H}}_2\text{O(g)}$ should be calculated.

Concept introduction:

Equilibrium constant expression for gas phase reactions are written using partial pressures as follows:

$\text{aA(g) }\rightleftharpoons \text{ bB(g) + cC(g)}$

Or,

${\text{K}}_P=\frac{{\left(P_B\right)}^b{\left(P_C\right)}^c}{{\left(P_A\right)}^a}$

Here, P_A, P_B and P_C are partial pressures of A, B and C gases respectively.

The concentration or partial pressure of pure solids and pure liquids are not included in the equilibrium constant expression.

The relationship between K_p and K_c is given by the following equation:

$K_p=K_c{\left(RT\right)}^{\Delta n}$

Here,

K_p = equilibrium constant in terms of partial pressure

K_c = equilibrium constant in terms of concentrations.

R = Universal gas constant

T = absolute temperature

$\Delta n=\text{ moles of gaseous products - moles of gaseous reactants}$