Question

Calculate Ka for an acid whose 0.30 M solution has a percent ionization of 2.1 x 10-3%.
HA + H2O ---> H3O+ + A-
Select one:

Answer 1

a. 3.98 x 10-11
b. 7.52 x 10-5
c. 6.3 x 10-6
d. 1.33 x 10-10

Answer 2

\(\sf K_A=\dfrac{(percent~ionization*[HA])^2}{[HA]-percent~ionization*[HA]}=\dfrac{[(2.1*10^{-3}\%)*0.3]^2}{0.3-[0.3*(2.1*10^{-3}\%)]}\)

Answer 3

^you can arrive at this result by constructing an I.C.E. table.