Chemistry: Calculate the pH of a 0.46 M solution of NH 4Cl. ( K b for NH 3 = 1.8 × 10 –5) a. 9.59 b. 4.41 c. 4.80 d. 0.34 e. 9.20

Calculate the pH of a 0.46 M solution of NH 4Cl.

clairefc2019

05.02.2022

pH of the solution = 4.8

Further explanation

NH₄Cl is a salt of a weak base and a strong acid so that it will be partially hydrolyzed

Reaction:

NH₄Cl -----> NH₄⁺ + Cl⁻

NH₄ will be hydrolyzed in water

NH₄⁺ + H₂O ------> NH₃ + H₃O⁺ (H⁺)

This solution releases H⁺ ions so they are acidic

Formula

$\tt [H^+]=\sqrt{\dfrac{Kw}{Kb}.M }$

Kw = The water equilibrium constant = 10⁻¹⁴

Kb = the ionization constant of a base = 1.8.10⁻⁵

M = 0.46

$\tt [H^+]=\sqrt{\dfrac{10^{-14}}{1.8.10^{-5}}\times 0.46 }$

[H+]=√2.55 x 10⁻¹⁰ = 1.599 x 10⁻⁵

pH = - log [H+]

pH = 5-log 1.599 = 4.796≈ 4.8

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