Answer to Question #170660 in Chemistry for Hyeri

Question

Nitrous acid in 0.1 F solution is 5.4 percent ionized. Calculate the ionization constant for this acid.

Answer 1

Nitrous acid dissociation:

HNO₂ + H₂O = H₃O⁺ + NO₂^-

Ionization (dissociation) constant can be calculated using the formula:

K_a = [H₃O⁺] [NO₂^-] / [HNO₂]

Since the solution is 5.4 % ionized:

[H₃O⁺] = [NO₂^-] = 5.4 % × 0.1 F / 100% = 0.0054 F

[HNO₂] = 0.1 F - 0.0054 F = 0.0946 F

From here:

K_a = [H₃O⁺] [NO₂^-] / [HNO₂] = 0.0054 × 0.0054 / 0.0946 = 3.08 × 10^-4

Answer: 3.08 × 10^-4