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)
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?
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.