First, we have to convert the starting measurements for the HCl and CaCO3 content into moles so we can compare the ratios to the formula. 40cm^3=0.04dm^30.04dm^32.5mol.dm^-3=0.1 moles of HClmass/molar mass= moles5.67g/100=0.0567 moles of CaCO30.1 moles of HCl will fully react to 0.05 moles of CaCO30.0567>0.05 so HCl is the limiting reagent 0.1 moles of HCl fully reacting will produce 0.05 moles of CO2 as the coefficient of HCl is 2 and the coefficient of CO2 is 1.0.05 moles CO244 g/mol=2.2 grams of CO2(g)