A 50.00-mL solution of 0.0400 M hydrofluoric acid (K_a = 7.2 × 10^-4)is titrated with a 0.0153 M solution of NaOH as the titrant.What is the pH of at the equivalence point? (K_w = 1.00 × 10^-14) A) 7.59 B) 11.45 C) 6.41 D) 10.86 E) 3.14

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Quizplus · Accepted Answer

At the equivalence point in the titration of a weak acid with a strong base, the solution contains the conjugate base of the weak acid (in this case, fluoride ion, F-), and the pH is determined by the hydrolysis of this conjugate base. The pH can be calculated using the formula for the hydrolysis of the conjugate base and the Kb of the conjugate base, which can be found using the equation Kw = Ka * Kb. Given the Ka of HF and the Kw, we can find Kb and then use it to calculate the pH, which results in a value greater than 7, indicating a basic solution. The correct answer is the one that reflects a basic pH value consistent with the hydrolysis of a weak acid's conjugate base, which is option A, 7.59.

A 5000-ML Solution of 0