You carefully weigh out 10.00 g of caco3 powder and add it to 40.50 g of hcl solution. you notice bubbles as a reaction takes place. you then weigh the resulting solution and find that it has a mass of 46.40 g . the relevant equation is caco3(s)+2hcl(aq)→h2o(l)+co2(g)+cac l2(aq) assuming no other reactions take place, what mass of co2 was produced in this reaction?

4.1g

The law of conservation of mass saying that the mass can't be created or destroyed. That means the total weight of reactant should be equal to the total weight of the product. But, if the reaction creates a gas product, the gas produced could fly away and makes the product lighter. The mass of the CO2 that goes away in this reaction would be:

reactant=product 
caco3 + HCL solution = CO2 + resulting solution
10g + 40.5g= CO2+ 46.4
CO2= 50.5g- 46.4g= 4.1g