Answer:
The pH of a 0.0335 M solution of oxalic acid is approximately 1.214.
Step-by-step explanation:
To find the pH of a 0.0335 M solution of oxalic acid, we need to consider the dissociation of the acid into its respective ions. Oxalic acid (HOOCCOOH) is a diprotic acid, meaning it can donate two protons (H+ ions) in solution. The dissociation reactions are as follows:
1. HOOCCOOH ⇌ H+ + OOCCOOH
2. OOCCOOH ⇌ H+ + OOCOO-
The acid dissociation constant, Ka, is related to the concentration of the ions in solution. The pKa value is the negative logarithm of the Ka value.
Given pKa1 = 1.23 and pKa2 = 4.19, we can use these values to calculate the pH of the solution:
1. Calculate the concentration of H+ ions from the first dissociation:
[H+] = 10^(-pKa1) * [HOOCCOOH]
= 10^(-1.23) * 0.0335
= 0.0603 M
2. Calculate the concentration of H+ ions from the second dissociation:
[H+] = 10^(-pKa2) * [OOCCOOH]
= 10^(-4.19) * 0.0335
= 0.000682 M
3. Calculate the total concentration of H+ ions in solution:
[H+]total = [H+] from the first dissociation + [H+] from the second dissociation
= 0.0603 + 0.000682
= 0.06098 M
4. Calculate the pH using the concentration of H+ ions:
pH = -log10[H+]
= -log10(0.06098)
≈ 1.214
Therefore, the pH of a 0.0335 M solution of oxalic acid is approximately 1.214.