Calculate the approximate pH of a 0.100 M solution of formic acid (HCO₂H) in water. (HCO₂H: K_a = 1.8 x 10^-4)

Question

Quizplus · Accepted Answer

The pH of a solution of a weak acid can be calculated using the formula pH = 1/2(pKa - log[C]), where pKa = -log(Ka). For formic acid, pKa = -log(1.8 x 10^-4) ≈ 3.74. Substituting into the formula gives pH ≈ 1/2(3.74 - log(0.100)) = 1/2(3.74 - (-1)) ≈ 2.37, which is closest to choice A, 2.4.

Calculate the Approximate PH of a 0