C3 - Quantitative Chemistry

• Conservation of Mass


  The total mass of the products of a chemical reaction is always equal to the total mass of the reactants
• Half equation


  • Used to show what happens to one of the reactants in a chemical reaction
• Ionic equation


  • A simplified version of a chemical equation, which just shows the species that are involved in the reaction
• Species


  • The different atoms, molecules or ions that are involved in a reaction
• Relative formula mass (Mr)


  The sum of the relative atomic masses of all the atoms shown in the formula
• Relative atomic mass (Ar)


  •The ratio of the average mass per atom of the element to one-twelfth the mass of an atom of carbon-12 •The number above the element name in the periodic table
• Concentration


  The amount of substance in a given volume, normally measured in units of mol/dm³
• Mole (mol)


  The unit for measuring the amount of substance; one mole of any substance contains the same number of particles; the mass of one mole of a substance is equal to the relative formula mass in grams
• Avogadro constant


  •The number of particles in one mole of any substance

  •6.02 x 10^23
• Limiting reactant


  The reactant that is completely used up in a reaction; it stops the reaction from going any further and any further products being produced
• Calculating the amount of substance

  mass of substance (g) ÷ atomic mass (g/mol)
• Due to conservation of mass, the sum of the relative formula masses of all the reactants is always equal to the sum of the relative formula masses of all the products
• Percentage mass of an element in a compound ( times this by 100 to get %)


  Ar × number of atoms

  % Mass = --------------------

  Mr of the compound
• 1 mole of a substance has a mass (g) equal to it's relative formula mass (Mr)
• No. of moles = mass of substance / Mr of substance
• Concentration (g/dm^3) = mass (g) / volume (dm^3)