Question

A 21.5997 g sample of impure magnesium carbonate was heated to complete decomposition
according to the equation
MgCO3(s) → MgO(s) + CO2(g).
After the reaction was complete, the solid
residue (consisting of MgO and the original
impurities) had a mass of 15.5207 g. Assuming that only the magnesium carbonate had
decomposed, how much magnesium carbonate was present in the original sample?
Answer in units of g

Answer 1

21.5997-15.207 = ? = mass CO2
g CO2 x (1 mol MgCO3/1 mol CO2) = g MgCO3.

Answer 2

I don't know eather!

Answer 3

That should be 21.5997-15.5207 = mass CO2.

Answer 4

I assume you mean either.