Question

A solution contains 0.236 M potassium hypochlorite and 6.74×10^-2 M hypochlorous acid.

The pH of this solution is

Answer 1

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The answer is pH=8.00

Given a buffer solution of weak acid and it's conjugate base.

Potassium hypochlorite (KOCl) will give K⁺ and OCl^- ions in aqueous solution.

K⁺ will not have any effect on pH of solution and   OCl^- ion reacts with water and forms HClO (HYPOCHLOROUS ACID).

From Henderson Equation of a Buffer consisting weak acid and it's conjugate base We have formulae to determine pH ofsolution

pH=pKa+log{ (Conjugate Base) / (Weak acid) }

pKa of HClO is 7.46 which is a standard value

pH= 7.46 + log{ (0.236)/(0.0674) } (6.74*10^(-2)=0.0674)

pH= 7.46+0.54

pH= 8.00

The answer is pH=8.00