Question

Henry's law constant for CO2 at 38°C is 2.28 × 10−3 mol / L · atm. Calculate the pH of a solution of CO2 at 38°C in equilibrium with the gas at a partial pressure of 5.30 atm.

Answer 1

Partial pressure of the CO_2 P_CO_2 = 5.30 atm Henry's constant of CO_2 at 38 degree C = k = 0.00228 m/L atm Molar solubility of CO_2 gas, = k p_CO_2 = (0.00228) (5.30) = 120 times 10^-2 = 0.0120 mol/L (or) m CO_2 + H_2O Rightarrow H_2CO_3 [H_2CO_2] = 0.0128 m H_2CO_3 (aq) + H_2O (l) Rightarrow HCO_3^- (aq) + H_3O + (aq) I: 0.0128 0 0 C: x +x + x M: (0.0.128 - x) x x 1^st k_a_1 = [HCO_3^-] [H_3O^+]/[H_2CO_3] 9.3 times 10^-7 = (x) (x)/0.0128 - x x^2 + 4.3 times 10^-7 times -5.5 times 5.50 times 10^-9 = 0 x = 7.39 times 10^-5 m [HCO_3^-] = [H_3O^+] = x = 7.39 times 10^-5 m HCO_3^- (aq) + H_2O (l) Rightarrow CO_3^-2 (aq) + H_3O^+ (aq) I 7.39 times 10^-5 0 7.39 times 106-5 C -x +x +x E 7.39 times 106-5 - x x 7.39 times 106-5 + x 2^nd k_a_1 = [HCO_3^-] [H-3O]/[H-2CO-3]