A crucible and sample of CaCO₃, weighing 42.670 g, was heated until red hot in order to decompose the sample.

CaCO₃(s) $\rightarrow$ CaO(s) + CO₂(g)
The empty crucible weighed 35.351 g. What is the theoretical weight of the crucible and residue after the decomposition is complete?

Question

A crucible and sample of CaCO₃, weighing 42.670 g, was heated until red hot in order to decompose the sample.

CaCO₃(s)

\rightarrow

CaO(s) + CO₂(g)
The empty crucible weighed 35.351 g. What is the theoretical weight of the crucible and residue after the decomposition is complete?

Quizplus · Accepted Answer

The weight of the residue (CaO) is the initial weight of CaCO3 minus the weight of CO2 released. The molar mass of CaCO3 is 100.09 g/mol, and CaO is 56.08 g/mol. The weight of CaO is (42.670 g - 35.351 g) * (56.08/100.09) + 35.351 g = 39.451 g.

A Crucible and Sample of CaCO3, Weighing 42 →\rightarrow→ CaO(s) + CO2(g) the Empty Crucible Weighed 35

A Crucible and Sample of CaCO₃, Weighing 42 $\rightarrow$ CaO(s) + CO₂(g)
the Empty Crucible Weighed 35