Question

If a `5.0*g` mass of calcium carbonate is strongly heated to give a `2.8*g` mass of calcium oxide, and a `2.2*g` mass of carbon dioxide, how does this demonstrate the conservation of mass? How is this represented as an equation?

Answer 1

`CaCO_3(s) + Delta rarr CaO(s) + CO_2(g)uarr`

Explanation:

Is mass balanced in the given equation? We started with a mass of `5.0*g` of calcium carbonate; from the reaction we get a mass of `2.8*g` of oxide, and `2.2*g` of gas. `(2.8+2.2)*g=5.0*g` as required, and mass is manifestly conserved.

We can take this further, and investigate the particle nature of calcium carbonate, and we have a molar quantity of `(5.0*g)/(100.09*g*mol^-1)=0.05*mol` of calcium carbonate, and we get a `0.05*mol` of calcium oxide, and a `0.05*mol` quantity of carbon dioxide gas.

AS in this reaction, and EVERY other chemical reaction EVER performed, mass is conserved.