Amounts of substances in equations

• The masses of reactants and products can be calculated from balanced symbol equations
• Chemical equations can be interpreted in terms of moles. For example:

  Mg + 2HCl —> MgCl2 +H2

  shows that one mole of magnesium reacts with two moles of hydrochloric acid to produce one mole of magnesium chloride and one mole of hydrogen gas