Question

How to calculate the pH of NH4OH(0.1M)

Answer 1

Answer is: pH of ammonium hydroxide is 11.13.
Chemical reaction of ammonium hydroxide in water: NH₄OH → NH₄⁺ + OH⁻.

Kb(NH₄OH) = 1,8·10⁻⁵.
c₀(NH₄OH) = 0.1 M.
c(NH₄⁺) = c(OH⁻) = x.
c(NH₄OH) = 0.1 M- x.
Kb = c(NH₄⁺) · c(OH⁻) / c(NH₄OH).
0,000018 = x² /  0.1 mol/L - x.

Solve quadratic equation: x = c(OH⁻) = 0.00133 M.

pOH = -logc(OH⁻).

pOH = 2.87.

pH = 14 - 2.87.

pH = 11.13.