The amount of calcium carbonate (CaCO3; molar mass 100.1 g/mol) in the ore dolomite can be determined by gravimetric analysis. The dolomite sample is dissolved in acid and the calcium ions (Ca2+) present are precipitated as calcium oxalate (CaC2O4; molar mass 128.1 g mol/1). The calcium oxalate is fltered, driedand strongly heated to form calcium oxide (CaO; molar mass 56.1 g mol).In one analysis the mass of dolomite used was 3.72 g. The mass of calcium oxide formed was found to be 1.24 g.The percentage of calcium carbonate in the dolomite sample is closest to:A. 26.9B. 33.3C. 56.0D. 59.5Two possible sources of error in this analysis areI. the precipitate of calcium oxalate is not rinsed with water after being fltered.II. the calcium oxide is not heated to constant mass.Which of these two errors, if any, would lead to a result that is too high?A. I onlyB. II onlyC. both I and IID. neither I nor II
moles CaO 1.24 g / 56.1 0.0221 moles CaC2O4 moles CaCO3 mass CaCO3 0.0221 mol x 100.1 g/mol2.21 g % 2.21 x 100/ 3.72 59.5 C
