For carbonic acid (H₂CO₃), K_a1 = 4.30 *10^-⁷ and K_a2 = 5.62 *10^-¹¹. Calculate the pH of a 0.50 M solution of Na₂CO₃.

Question

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The correct answer is A because the pH of a 0.50 M solution of Na2CO3 can be calculated using the dissociation constants of carbonic acid (H2CO3) and the ICE table. The first dissociation constant (Ka1) for carbonic acid is 4.30 x 10^-7 and the second dissociation constant (Ka2) is 5.62 x 10^-11. The ICE table shows the initial concentrations of the species in the solution, the changes in concentrations after the first and second dissociation steps, and the equilibrium concentrations. The pH of the solution can then be calculated using the equilibrium concentrations of H+ and OH- ions.

For Carbonic Acid (H2CO3), Ka1 = 4

For Carbonic Acid (H₂CO₃), K_a1 = 4