Homework SourseCalculate the pH of a weak acid solution quadratic equation
Calculate the pH of a weak acid solution (quadratic equation).
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Calculate the pH of a 0.182 M aqueous solution of chlorous acid (HClO2, Ka = 1.1×10-2) and the equilibrium concentrations of the weak acid and its conjugate base.
| pH | = | _______________ |
| [HClO2]equilibrium | = | _______________ M |
| [ClO2- ]equilibrium | = | ________________M |
Solution
HClO2 + H2O <===> H3O^+(aq) + ClO2^-(aq)
Ka = [H3O+][ClO2^-] /[HClO2 ]
[H3O+] = [ClO2^-]
[H3O+]^2 = Ka x [HClO2] => 1.1*10^-2 * 0.182
[H3O^+] = 0.0447 M
pH = - log (0.0447)
pH = 1.35
At equilibrium [ClO2^-] = 0.0447 M
At equilibrium [HClO2] = 0.182 - 0.0447 => 0.1373 M
