Question

Calculate the approximate pH of an aqueous solution of sodium carbonate Na₂CO₃ , 0.28 M, at 25°C. (Note: consider one decimal place for the pH answer.)

pKa H₂CO₃ /HCO₃⁻ = 6.35, pKa HCO₃^- /CO₃^2-= 10.30

Answer 1

CO2- 11 Ka I HCO3 + ht kan но Ht ton ka tu (032- (aq) + H2O(l) HCO₃-coq) toti cea) K = alb take place reaction only appreciable two lo-14 10 -3.7 = 1.995 x 10-4 . 10-10.3 H Cog-laqst on-lags CO₂ a Carq) + H₂O (2) с x guilial! Eqb: C - x x² liggs x lo-t K = [hco;-] con- icazz-3 (0.28 - x) to be small 1., 0:28 - x 0.28 متها assume 1.995 x 0.28 x 10-4 0 74 74 x 10-2 TY 7-474 x 10-3 :: OH-3 2.1264 3 Con-I log - log! 17.474) = pona pH = 14 14 -poh on, 2.1264 - 11.8736 11.9 (A decimal placed 11.9 the solution Роли, pH of given