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Question 9 When 0.0031 moles of a weak acid are dissolved in enough water to make 0.500 L, the pH of the resulting solution is 4.36 Calculate K Incorrect Mark 0.00 out of 1.00 Answer 2.71e-7 Flag question

Answer 1

0.0031 mol/0.500 L = 0.0062 m change P^H to [H^+] like this [H^+] = 10^- PH = 10^- 4.36 = 4.36 times 10^- 5 m The weak aid ionizes as follows HA rightarrow H^+ + A^- from this, we know that [A^-] = 4.36 times 10^- 5 k_a = [(4.36 times 10^- 5) (4.36 times 10^- 5)]/[0.0062] = 1.90096 times 10^- 9/0.0062 k_a = 3.066 times 10^- 7