Butyric acid is responsible for the odor in rancid butter. A solution of 0.25 M butyric acid has a pH of 2.71. What is the K_a for the acid?

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Quizplus · Accepted Answer

The pH of 2.71 corresponds to an H⁺ concentration of about 1.95 × 10⁻³ M. Using the formula for Kₐ = [H⁺]² / [HA], where [HA] is the initial concentration of the acid (0.25 M), the Kₐ is calculated to be approximately 1.5 × 10⁻⁵.

Butyric Acid Is Responsible for the Odor in Rancid Butter