Gradebook PrintCalculatorPeriodic Table uestion 23 of 23 Sap

Gradebook PrintCalculatorPeriodic Table uestion 23 of 23 Sapling Learning The K of a monoprotic weak acid is 7.68x10. What is the percent ionization of a 0.147 M solution of this acid? Number Incorrect. 1228m_ %1 isnotvalid. Youshouldusethe The assumption you made is not valid. You should use the quadratic equation instead

Solution

HA + H2O = H3O^+ + A^-

For which Ka = 7.68 * 10^-3

Ka = [ H3O^+ ] [ A^- ] / [ HA ]

let [ H+ ] = x

Ka = x^2 / 0.147 - x

x^2 = ( 7.68 *10^-3) * ( 0.147 - x)

x^2 = 0.00113 - 7.68*10^-3 x

x^2 + 7.68 * 10^-3 x + 0.00113 = 0

solve quadratic equation for x

x = 0.0299

[ H+ ] = 0.0299

% dissociation = [ H+] / [ HA ] *100

% dissociation = 0.0299 / 0.147 * 100

% dissociation = 20.34 %