# I have no idea how to solve this problem, please help me out.... thanks

a) A liter of a solution saturated at 25degree with calcium oxalate, CaC2O4, is evaporated to dryness, giving a 0.0061gm residue of CaC2O4. calculate the concentrations of the ions, and molar solubility and the solubility product constant for this salt at 25 degree C.

b)answer the above question, using a solution of 0.15M CaCl2 as the solvent instead of pure water.

So you have 0.0061 g CaC2O4 per liter of solution.

How many mols is that?

Isn't that also the molarity since it is in 1 L?

Now write the solubility equation.

CaC2O4 ==> Ca^+2 + C2O4^=

Ksp = (Ca^+)(C2O4^=) .

Plug in the values for the molarity and calculate Ksp. Post you work if you get stuck.

For part b, same thing EXCEPT you have more Ca^+ than in the saturated solution of water alone.