concentration of calcium

[rainashley]

if i add 4x10 -4 M CaCl2 to 1 x 10 -3 Cl-
Ksp of CaCl2 = 4 x10 -18
What is the final concentration of calcium and chloride?


I understand that I do Keq=[Ca][Cl]2
and its like a common ion thing where i cross out 2x since its negligible
x = 4 x 10 -12 M for Ca+2
So if I want to find Cl do I do 2(4 x 10 -12 + 1 x 10 -3)? Is that right?
Or do I have to square it too?
Thanks

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[rainashley]

?

 

[wooki]

this isn't the full question. i am pretty sure this is from one of the AAMC test. type out the whole question if you really want help, or look in the AAMC test subforums.

since i forgot what chemical reaction you are doing, i can't really help you get the answer. CaCl2 + Cl -> ?