Percentage composition of compounds

• Chemical equation


  Reaction information shown using word and symbol equations
• Mass is conserved in chemical reactions
• No atoms are made or destroyed in chemical reactions
• Relative atomic mass


  Used to find the relative formula mass of a compound
• Percentage composition of compounds

  Percentage of a compound that is made from a particular element
• Calculating percentage composition


  Work out the M_r of the compound

  2. Work out the total A_r of the element

  3. Divide the total A_r of the element by the M_r of the compound, then multiply by 100
• Percentage composition examples


  • Percentage of calcium in calcium carbonate, CaCO_3

  Percentage of iron in iron(III) oxide, Fe_2O_3