A 25.0-mL sample of 0.150 M hydrocyanic acid is titrated with a 0.150 M NaOH solution. What is the pH before any base is added? The K_a of hydrocyanic acid is 4.9 × 10^-10. A)5.07 B)8.6 × 10^-6 C)9.31 D)8.49 E)3.1 × 10⁸

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Quizplus · Accepted Answer

The pH before any base is added is determined by the dissociation of hydrocyanic acid (HCN). Using the formula for weak acid dissociation, pH = -log[H⁺], where [H⁺] is calculated from the expression √(Ka × [HCN]), we find the pH to be approximately 5.07.

A 250-ML Sample of 0