A weak acid solution of 0.24 M has a pH of 3.49. Determine the Ka value of this weak acid? Question 15 options: 6.4x10-8 4.37x10-7 2x10-6 1.8x10-5

Question

A weak acid solution of 0.24 M has a pH of 3.49. Determine the Ka value of this weak acid?

Question 15 options:

	6.4x10-8
	4.37x10-7
	2x10-6
	1.8x10-5

Answer 1

HA ==> H⁺ + A^-

Ka = [H+][A-] / [HA]

[H⁺] is obtained from the pH: [H⁺] = 1x10^-3.49 = 3.24x10^-4 M

Ka = (3.24x10^-4)² / 0.24

Ka = 4.37x10^-7

Not sure how you arrived at 1.8x10^-5 since you didn't show your work.