When 20 grams of calcium carbonate decomposes, how many grams of calcium oxide are produced?

Answer 1

Two ways to do this, one short way and one long way.
Long way.
CaCO3 ==> CaO + CO2
mols CaCO3 = grams/molar mass = ?
Using the coefficients in the balanced equation, convert mols CaCO3 to mols CaO.
Then convert to g CaO. g CaO = mols CaO x molar mass CaO.

Short way.
20 g CaCO3 x (molar mass CaO/molar mass CaCO3) = ?g CaO.