Question

Bone was dissolved in hydrochloric acid, giving 48.0 mL of solution containing calcium chloride, CaCl2. To precipitate the calcium ion from the resulting solution, an excess of potassium oxalate was added. The precipitate of calcium oxalate, CaC2O4, weighed 1.437 g. What was the molarity of CaCl2 in the solution?

Answer 1

mm = molar mass
grams CaCl2 = grams CaC2O4 x (mm CaCl2/CaC2O4) = 1.437 x (mm CaCl2/mm CaC2O4) = ?
Then moles CaCl2 = grams CaCl2/mm CaCl2 = ?
Finally, M CaCl2 = mols CaCl2/L of solution = moles CaCl2/0.048L = ?
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