Answer to Question #149065 in General Chemistry for Flexus

Question

Solve the problems below and show the complete solution.

1.) Calculate the pH of a carbonate buffer system that contains 0.0065 M HCO3- and 0.0084 M CO32-.
( Ka of HCO3- is 4.7x10-11)

Answer 1

HCO₃^- = H⁺ + CO₃^2-

Ka=[H⁺]*[CO₃^2-]/[HCO₃^-] = [H⁺]*c(CO₃^2-)/c(HCO₃^-) = 4.7*10^-11

[H⁺] = Ka*c(HCO₃^-)/c(CO₃^2-) = 4.7*10^-11*0.0065/0.0084 = 3.6369*10^-11

pH = -log₁₀([H⁺]) = -log₁₀(3.6369*10^-11) = 10.44