Calculate the pH of a 0.345 mol L^-1 solution of formic acid, K_a = 1.8 × 10^-4. A) 2.10 B) 2.49 C) 3.17 D) 1.60 E) 2.04

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The pH of a weak acid can be calculated using the Henderson-Hasselbalch equation:pH = pKa + log([A-]/[HA])where pKa is the negative logarithm of the acid dissociation constant, [A-] is the concentration of the conjugate base, and [HA] is the concentration of the acid.For formic acid, K_a = 1.8 × 10^-4, so pKa = -log(1.8 × 10^-4) = 3.74.Let x be the concentration of H+ ions in the solution. Then, the concentration of formate ions ([A-]) will be 0.345 - x, and the concentration of formic acid ([HA]) will be x.Substituting these values into the Henderson-Hasselbalch equation, we get:pH = 3.74 + log((0.345 - x)/x)Solving for x, we get:x = 2.10 × 10^-3 MTherefore, the pH of the solution is:pH = -log(2.10 × 10^-3) = 2.10

Calculate the PH of a 0