J.R. S. answered 05/17/25
Ph.D. University Professor with 10+ years Tutoring Experience
CaCO3(s) <==> Ca2+(aq) + CO32-(aq) ... Kp = 3.2x10-9
Ksp = [Ca2+][CO32-]
3.2x10-9 = (0.0025)(x) since Ca2+ is a common supplied by Ca(NO3)2
x = [CO32-] = 1.28x10-6 M = 1.3x10-6 M (doesn't agree with your answer. Differs by 10 fold)
Co(OH)2(s) <==> Co2+(aq) + 2OH-(aq)
Q = [Co2+][OH-]2
Q = (0.33)(3.33x10-4)2
Q = 3.66x10-8 = 3.7x10-8
Since Q is greater than Ksp, a precipitate WILL form.
The answers to both questions should have 2 significant figures.