Carboxylic acids are weak acids and dissociate in aqueous solution to the carboxylate anion. The extent of dissociation is given by the equilibrium dissociation constant; K_a, which is often expressed in its logarithmic form as pK_a (The cation is written simply as H⁺ and is understood to be solvated with one or more water molecules in solution ) If a butyric acidlbutyrate buffer is 0.020 M in butyric acid and has a pH of 4.91, what is the molar concentration of the butyrate ion? The pK_a of butyric acid is 4.81.

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