100 ml each of a 0.003M solution of Ba^2+ (aq) and a 0.002M solution of CO3^2- (aq) are mixed. Will a precipitate form?

Question

100 ml each of a 0.003M solution of Ba^2+ (aq) and a 0.002M solution of CO3^2- (aq) are mixed. Will a precipitate form?

ksp for BaCo3= 5.0*10^-9

a)precipitate will form

b)system is at equilibrium

c)precipitate will not form

d)not enough information given

Answer 1

To determine if a precipitate forms, you want to compare Q to Ksp.

We are given the Ksp, so we need to find Q (reaction quotient).

100 ml of 0.003 M Ba²⁺ = 0.1 L x 0.003 mol/L = 0.0003 moles Ba²⁺

100 ml of 0.002 M CO₃^2- = 0.1 L x 0.002 mol/L = 0.0002 moles CO₃^2-

BaCO₃(s) <==> Ba²⁺(aq) + CO₃^2-(aq)

Q = [Ba²⁺][CO₃^2-] = (0.0003)(0.0002)

Q = 6x10^-8

Compare this to Ksp of 5x10^-9

Q > Ksp so a precipitate WILL form