Answer:
3.47 x 10⁻⁹.
Explanation:
- The concentration of OH⁻ = 0.16 M.
∵ [OH⁻] = √(Kb)(C).
Kb for ammonia = 1.8 x 10⁻⁵.
∴ [OH⁻] = √(Kb)(C) = √(1.8 x 10⁻⁵)(0.16 M) = 2.88 x 10⁻⁶ M.
∵ [H⁺][OH⁻] = 10⁻¹⁴.
∴ [H⁺] = 10⁻¹⁴/[OH⁻] = 10⁻¹⁴/(2.88 x 10⁻⁶) = 3.47 x 10⁻⁹ M.
∵ pH = - log[H⁺] = - log(3.47 x 10⁻⁹) = 8.459 ≅ 8.46.
