# Problem: The value of Ka for nitrous acid (HNO2) at 25 °C is 4.5×10−4.a. Write the chemical equation for the equilibrium that corresponds to Ka1. H+(aq) + NO−2(aq) ⇌ HNO2(aq)2. HNO2(aq) ⇌ H+(aq) + NO−2(aq)3. HNO2(aq) ⇌ H−(aq) + NO+2(aq)4. HNO2(aq) + H+(aq) ⇌ H2NO+2(aq)5. HNO2(aq) + H−(aq) ⇌ H2NO+2(aq)b. By using the value of Ka , calculate ΔG° for the dissociation of nitrous acid in aqueous solution.  c. What is the value of ΔG at equilibrium?        d. What is the value of ΔG when [H+] = 5.9  ×10−2 M , [NO−2] = 6.7 × 10−4 M , and [HNO2] = 0.21 M ?

###### FREE Expert Solution

A.

$\overline{){{\mathbf{K}}}_{{\mathbf{a}}}{\mathbf{=}}\frac{\mathbf{products}}{\mathbf{reactants}}{\mathbf{=}}\frac{\left[{H}^{+}\right]\left[{{\mathrm{NO}}_{2}}^{-}\right]}{\left[{\mathrm{HNO}}_{2}\right]}}$

###### Problem Details

The value of Ka for nitrous acid (HNO2) at 25 °C is 4.5×10−4.

a. Write the chemical equation for the equilibrium that corresponds to Ka

1. H+(aq) + NO−2(aq) ⇌ HNO2(aq)

2. HNO2(aq) ⇌ H+(aq) + NO−2(aq)

3. HNO2(aq) ⇌ H(aq) + NO+2(aq)

4. HNO2(aq) + H+(aq) ⇌ H2NO+2(aq)

5. HNO2(aq) + H(aq) ⇌ H2NO+2(aq)

b. By using the value of Ka , calculate ΔG° for the dissociation of nitrous acid in aqueous solution.

c. What is the value of ΔG at equilibrium?

d. What is the value of ΔG when [H+] = 5.9  ×10−2 M , [NO−2] = 6.7 × 10−4 M , and [HNO2] = 0.21 M ?