Chapter 23, Problem 23.27P

Interpretation Introduction

Interpretation:

Value of ${\text{ΔG}}_{rxn}^o$ at $25°C$ has to be calculated. The dissociation of nitrous acid whether takes place spontaneous has to be identified when $\left[N{O}_2^{-}\right]=\left[H_3{O}^{+}\right]=\left[{\text{HNO}}_{\text{2}}\right]=1.00\text{ M}$. Also, the value of ${\text{ΔG}}_{rxn}$ and the dissociation is whether spontaneous has to be determined when $\left[N{O}_2^{-}\right]=\left[H_3{O}^{+}\right]=1.0\times {10}^{-5}\text{ M}$ and $\left[{\text{HNO}}_{\text{2}}\right]=1.0\text{ M}$.

Concept Introduction:

The Gibbs free energy or the free energy change is a thermodynamic quantity represented by $\Delta G$. Value of $\Delta G_{rxn}^o$ is determined as follows,

  ${\text{ΔG}}_{rxn}^o=-\text{RT}\text{ln K}$

The formula of ${\text{ΔG}}_{\text{rxn}}$ in is given below,

    ${\text{ΔG}}_{rxn}=\text{RT}\text{ln }\left(\frac{{\text{Q}}_c}{K_c}\right)$

If $Q_c>{\text{ K}}_c$ then the reaction is spontanous in backward reaction (from right to left).

If $Q_c{\text{< K}}_c$ then the reaction is spontanous in forward reaction (from left to right).

If $Q_c={\text{ K}}_c$ then the reaction will be at equilibrium.

K_a is the equilibrium constant referring to the dissociation of a particular acid.