What is the [C2O4] in the resulting solution when a strong acid is added to .015M oxalic acid until pH of 0.5?

Answer 1

You know that [H+] x [(C2O4)2-] = Ka.

If pH = 0.5, [H+] = 10(-0.5) - ten to the power of -0.5.

So [(C2O4)2-] = Ka/[H+]