Question

Malonic acid [ molecular formula C₃H₄O₄] is a diprotic acid with pKa₁ = 2.83 and pKa₂ = 5.69 . Determine the concentrations of the neutral acid, the monoanion and the dianion [H₂A, HA^- and A^2-] in a solution contaning 50.0 mg of malonic acid in 1.00 liter of solution.

Answer 1

1 mol 1000 mg 1.00L 104. 1 g-480x10-M Concentrati on of malonic acid, H2A - ICE table constructedis as follows; I(M) 480x10 C(M) E(M) (4.80×10%) ズ 1st aci dionization constant.KH A 10-1.5x103 4.80x10-4-x x 3.82 x104 M From the equilibrium table, [H,0 x 3.82x10-*M [HA]- (4.80x104-x)M -(480x101-382x10)M 9.80x10M ICE table constructed for the 2ndionization of HA is as follows HA (a) + H(aa)H(aa) I(M) 3.82x10 C(M) E(M): (3.82 x 10-x) 3.82x1оґ 3.82x10+x 2nd acidionizati on constant, K,2 - HA-1 (3.82x10* +x)() -3.82x10-4- 10-569= 204 x10 x- 2.02x10-6 According to the equilibrium table, AM 202x10M According to the equilibrium table. ГНА--(3.82x10-4-r)M 2( 3.82 × 10.2.02 × 10-6)M= 3.80×10-4 M = (3.82×10, 2.02×10-6 )M 3.84x104M pH-log [H3Ơ ]--log (3.84x10-4)-3.42