A 4.50 g sample of limestone (impure CaCO3) was dissolved in 0.1M HCl solution according to the following equation. CaCO3(s) + 2HCl(aq) → CaCl2 (aq) + CO2 (g) + H2O (l) Excess of (NH4)2C2O4(aq), was added to the resulting solution to precipitate the calcium ions as calcium oxalate, CaC2O4(s). Ca2+(aq) + C2O42-(aq) → CaC2O4 (s) The precipitate was filtered, dried and weighed at 2.15 g. (Show your work) a) Determine the percentage by mass of calcium carbonate (CaCO3) in the limestone sample. (MM of CaCO3 is 100.09 g/mol) b) Why we need to dry the precipitate until we get a constant mass? c) Is the precipitate of calcium oxalate (CaC2O4) stable and in the final form or not? Explain.
A 4.50 g sample of limestone (impure CaCO3) was dissolved in 0.1M HCl solution according to the following equation.
CaCO3(s) + 2HCl(aq) → CaCl2 (aq) + CO2 (g) + H2O (l)
Excess of (NH4)2C2O4(aq), was added to the resulting solution to precipitate the calcium ions as calcium oxalate, CaC2O4(s).
Ca2+(aq) + C2O42-(aq) → CaC2O4 (s)
The precipitate was filtered, dried and weighed at 2.15 g.
(Show your work)
a) Determine the percentage by mass of calcium carbonate (CaCO3) in the limestone sample.
(MM of CaCO3 is 100.09 g/mol)
b) Why we need to dry the precipitate until we get a constant mass?
c) Is the precipitate of calcium oxalate (CaC2O4) stable and in the final form or not? Explain.
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