The Ksp for BaCrO4 is 1.2X10-10. Will BaCrO4 precipitate when 10 mL of 1 X10-5M Ba(NO3)2 is mixed with 10 mL of 1X10-3M K2CrO4?

Question

I am not sure where to start

Answer 1

You want to calculate Qsp and compare that with Ksp.
Ba(NO3)2 + K2CrO4
You are given concns before mixing.
After mixing each is diluted by factor of 2. New concns are
(Ba^2+) = 1E-5M x (10 mL/20 mL) = ?
(CrO4^2-) = 1E-3 x (10 mL/20 mL) = ?

Plug those new concns and calculate Qsp. If Qsp > Ksp there will be a ppt; if Qsp < Ksp there will be no ppt.