Help with Chemistry?

Question

Lead metal is added to .100 M Cr(3+) (aq). What are [Pb(2+)], [Cr(2+)], and [Cr(3+)] when equilibrium is established in the reaction?

Reaction:

Pb(s) + 2Cr(3+)(aq) <----> Pb(2+)(aq) + 2Cr(2+)(aq)

Kc = 3.2E-10

note: (s), etc is states, (2+), etc is oxidation number, or ion

Would someone tell me how to do this problem? I want to know the steps. Thank you.

Answer 1

Write the expression for Kc:

Kc = [Pb2+] x [Cr2+] squared/[Cr3+] squared

Let y = [Pb2+]

Then y x 2y squared/(0.1 - 2y) squared = Kc.

Now do some algebra!