A new organic acid was discovered and at 25 degrees celsius a 0.115 M solution of this acid in water had a pH of 3.42. Calculate the Ka for this acid

Question

jfraser · Answer

knowing the pH gets you the [H+]. knowing the starting concentration of acid allows you to set up an equilibrium table:

$$HA \space \space \space \space \space\rightleftharpoons H^+ \space + \space A^-$$
plug in the values for the [H+] and [A-] that you get from the pH, and solve for Ka.