Solve for

the number of grams of Ca2+
ion in a solution prepared by adding 1.00 gram of calcium oxalate (Ksp=1.3x10^-8)powder to 100 mL at pH 9.

1 answer

I'm assuming that at a pH of 9 the H^+ will not increase the solubility over that of a saturated solution of CaC2O4.

............CaC2O4 ==> Ca^2+ + C2O4^2-
I............solid......0........0
C............solid......x........x
E............solid......x........x

Ksp = (Ca^2+)(C2O4^2-)
Substitue the E line and solve for x = (Ca^2+) in mols/L. Correct for mols in 100 mL and convert to grams.