Question 8.4: Acid Strength Which is the stronger acid: (a) Benzoic acid w...

Introduction to General, Organic and Biochemistry [EXP-46650]

Acid Strength

Which is the stronger acid:

(a) Benzoic acid with a $K_{ a } \text { of } 6.5 \times 10^{-5}$ or hydrocyanic acid with a $K_{ a }$ of $4.9 \times 10^{-10}$ ?

(b) Boric acid with a $p K_{ a }$ of 9.14 or carbonic acid with a $p K_{ a }$ of 6.37?

Strategy

Relative acid strength is determined by comparing the $K_{ a }$ values or the $p K_{ a }$ values. If using $K_{ a }$ values, the stronger acid has the larger $K_{ a }$ . If using $p K_{ a }$ values, the stronger acid has the smaller $p K_{ a }$ .

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