A 0.180 m solution of a weak acid (ha) has a ph of 2.91. calculate the acid ionization constant (ka) for the acid.

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Chemistry

Sosa

1 June, 02:59

A 0.180 m solution of a weak acid (ha) has a ph of 2.91. calculate the acid ionization constant (ka) for the acid.

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Talon Santiago · Answer 1

Answer is: the acid ionization constant (Ka) for the acid is 8.46·10⁻⁶.

Chemical reaction: HA (aq) ⇄ H⁺ (aq) + A⁻ (aq).

pH = 2,91.

[H⁺] = 10∧ - 2,91 = 0,00123 M.

[H⁺] = [A⁻] = 0,00123 M.

[HA] = 0,18 M - 0,00123 M.

[HA] = 0,1787 M.

Ka = [H⁺] · [A⁻] / [HA].

Ka = (0,00123 M) ² / 0,1787 M.

Ka = 8,46·10⁻⁶ M.