Which Ka value would indicate a relatively stronger weak acid?

Which Ka value would indicate a relatively stronger weak acid?

• A. 10^-6
• B. 10^-7
• C. 10^-4
• D. 10^-9

Answer: (C)

The strength of a weak acid is determined by its acid dissociation constant, Ka. A larger Ka means the equilibrium lies more toward dissociation into H+ and A−, so more acid molecules split apart and the solution becomes more acidic. Among the given values, 1×10^-4 is the largest Ka, so it corresponds to the relatively stronger weak acid. The smaller values (1×10^-6, 1×10^-7, and 1×10^-9) indicate progressively less dissociation and thus weaker acids. In short, a bigger Ka signals a stronger weak acid.

The strength of a weak acid is determined by its acid dissociation constant, Ka. A larger Ka means the equilibrium lies more toward dissociation into H+ and A−, so more acid molecules split apart and the solution becomes more acidic. Among the given values, 1×10^-4 is the largest Ka, so it corresponds to the relatively stronger weak acid. The smaller values (1×10^-6, 1×10^-7, and 1×10^-9) indicate progressively less dissociation and thus weaker acids. In short, a bigger Ka signals a stronger weak acid.