The law of conservation of mass states that no atoms are lost or made during a chemical reaction so the mass of the products equals the mass of the reaction
A mass of 33.6g of magnesium carbonate (MgCO3) is completely decomposed when it was heated. It made 16.0g of magnesium oxide ( MgO). Calculate the mass of carbon dioxide produced.
Mass of C02 = mass of MgCO3 - mass of MgO = 33.6g - 16.0g = 17.6g
if a gas is a product in a reaction the mass appears to decrease this is because it is lost to the atmosphere.
If one of the reactants is a gas, then the products will appear to weigh more than the reactants. This is because the mass of the gas is added the mass of the reactants. ( wasn't weighed in the first place )
