Consider a 0.10 M solution of a weak polyprotic acid (H2 A) with the possible values of Ka1 and Ka2 given below. Calculate the contributions to [H3O+] from each ionization step.
Ka1 = 1.0x10 - 4 ; Ka2 = 5.0x10 - 5
We are being asked to calculate the contributions to [H3O+] from each ionization step in H2A.
• can donate two protons (H+) → diprotic acid
• two equilibrium equations → two equilibrium constants
• Equilibrium constants (Ka) given:
▪ Ka1 = 1.0x10-4
▪ Ka2 = 5.0x10-5
Construct an ICE Chart for the 1st equilibrium reaction: