A sample contained a mixture of MgCO3 and BaCO3. The amount of MgCO3 was determined by reacting 10.37 g of the sample with an excess of HCl to release CO2 from each compound; MgCO3(s) + 2 HCl(aq) ® MgCl2 + CO2(g) BaCO3(s) + 2 HCl(aq) ® BaCl2 + CO2(g) If the sample reacted completely and produced 2297 mL of carbon dioxide at 24.88 °C and 736.6 mm Hg, what was the mass percentage of MgCO3 in the mixture?