Question

What is the equilibrium concentration of hydrogen sulfite in a 0.150 M solution of H₂SO_3?

Answer 1

Ka for H2SO3 = 1.54 * 10^(-2)

                        H2SO3 ------> H+ + HSO3-

Initial                0.150            0        0

Final               (0.150-x)         x        x

Ka = [H+][HSO3-]/[H2SO3]

1.54 * 10^(-2) = x^2/(0.150-x)

x^2 + 1.54 * 10^(-2)x - 2.31 * 10^(-3) = 0

D = b^2 - 4ac = (1.54 * 10^(-2))^2 + 4(1)(2.31 * 10^(-3)) = 94.7716 * 10^(-4)

square root of D = 9.735 * 10^(-2)

x = [-1.54 * 10^(-2) + 9.735 * 10^(-2)]/2 = 0.040975M