Hclo is a weak acid (ka = 4.0 * 10-8) and so the salt naclo acts as a weak base. what is the ph of a solution that is 0.030 m in naclo at 25 °c?

Question

Tyree Frederick

Chemistry

13 August, 15:41

Hclo is a weak acid (ka = 4.0 * 10-8) and so the salt naclo acts as a weak base. what is the ph of a solution that is 0.030 m in naclo at 25 °c?

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Toby Ho · Answer 1

Chemical reaction 1: NaClO (aq) → Na⁺ (aq) + ClO⁻ (aq).

Chemical reaction 2: ClO ⁻ (aq) + H₂O (l) ⇄ HClO (aq) + OH⁻ (aq).

c (NaClO) = 0,030 M.

[ClO ⁻] = 0,03 M - x.

Ka (HClO) = 4·10 ⁻⁸.

Ka · Kb = 10 ⁻¹⁴.

Kb (ClO ⁻) = 2,5·10⁻⁷.

Kb (ClO ⁻) = [OH⁻] · [HClO] / [ClO⁻].

[OH ⁻] = [HClO] = x.

2,5·10 ⁻⁷ = x² / (0,03 M - x).

Solve quadratic equation: x = [OH ⁻] = 0.0000893 M.

pOH = - log (0.0000893 M) = 4.05.

pH = 14 - 4.05.

pH = 9.95.