Oxalate

The solubilty of calcium oxalate (CaC2O4) in urine is 9 x 10^-5 M. Ksp of CaC2O4 is 8.1 x10^-9. 

THe solubility of magnesium oxalate (MgC2O4) is 0.0093 M. Ksp of MgC2O4 is 8.65 x 10^-5.

If the concentration of Ca is 5 mM, the concentration of oxalate is 4.02 x 10^-5 mM.

a) The pH of subject A’s urine was 5.9. What fraction of total oxalate, cT, is present as oxalate ion, C2O4, at pH 5.9? The Ka values for oxalic acid in urine are the same as in water. Hint: find the ration C2O4 / cT at pH 5.9.

b) If the total oxalate concentration in Subject A’s urine was 15.0 mM, should a calcium oxalate precipitate form?