Question

"what is the ph of a 0.160 m ammonia solution"? express your answer numerically to two decimal places.

Answer 1

3.47 x 10⁻⁹.

Step-by-step 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.