Question

Benzoic acid is a weak acid that has antimicrobial properties. Its sodium salt, sodium benzoate, is a preservative found in foods, medications, and personal hygiene products. Benzoic acid ionizes in water:

C6H5COOH⇌C6H5COO−+H+

The pKa of this reaction is 4.2. In a 0.57 M solution of benzoic acid, what percentage of the molecules are ionized?

Express your answer to two significant figures and include the appropriate units.

Answer 1

                          

Initial                            0.57                          0                    0

Final                           (0.57 - x )                    x                    x

assuming (0.57-x) is equal to 0.57 we get

Percent Ionization =