Question

How many ionization constants are associated with oxalic acid (H2C2O4)?

Answer 1

There are 2 ionization constants associated with oxalic acid.

Answer 2

Answer: Two.

Explanation: Number of ionization constants associated with an acid equals to the number of hydrogen ions(protons) that it produces in aqueous solution.

For example, HCl is a monoprotic acid as it produces only one hydrogen ion in aqueous solution and so only one ionization constant is associated with it.

$H_2SO_4$ (sulfuric acid) is a diprotic acid as it produces two hydrogen ions in aqueous solution and hence there are two ionization constant values associated with this.

Similarly, Oxalic acid is also a diprotic acid and so two ionization constant values are associated with this.

The two ionization equations of oxalic acid are as follows:-

$H_2C_2O_4\rightleftharpoons H^++HC_2O_4^-$

$HC_2O_4^-\rightleftharpoons H^++C_2O_4^-^2$

$Ka_1$ and $Ka_2$ are the two ionization constants for first and second equations respectively.