If 10.0 g of CaCO3(s) is heated, 5.61 grams of solid CaO will remain (4.39 g CO2 gas is driven off)

Question

If 3.25 g of NaCl(s), which does not undergo decomposition, is mixed with 5.30 g of CaCO3(s) and the mixture is heated long enough to decompose all of the calcium carbonate, how many grams of solid will remain?

Answer 1

You CAN go through the stoichiometry and arrive at the amount of CaO remaining but a simpler way of working the problem is to ask yourself the percent CaO in CaCO3 (which you calculate from the first part of the problem). That is (5.61/10)*100 = ??

Apply that same percentage to 5.30 g to arrive at the amount CaO remaining, then add the amount NaCl in the original mixture. The sum should be the solid remaining after the reaction.