Stoichiometry

Cards (19)

  • Valency
    The amount of electrons an atom has to gain or lose in order to achieve a full outer shell
  • Valency
    • Groups 1-3 (metals) will LOSE electrons
    • Groups 5-7 (non-metals) will GAIN electrons
    • Group 4 can do either
  • Ion
    An atom that has lost or gained electrons, resulting in a charge
  • Determining chemical formula
    1. Know the valencies of the atoms
    2. Swap the numbers around
    3. Cancel out if valencies are equal
  • Word equation
    Chemical equation written in words
  • Symbol equation
    Chemical equation represented by symbols, must be balanced
  • Balancing chemical equations
    1. Ensure same number of each type of atom on both sides
    2. Cannot change original chemical formula
    3. Add numbers in front of reactants/products
  • State symbols
    Represent the physical state of reactants/products
  • Mole
    6.02 x 10^23 atoms, molecules or ions of a substance
  • Mole equations
    • Moles = Mass / Relative formula mass
    • Volume = Moles x 24 dm3/mol
    • Concentration = Moles / Volume
  • Relative formula mass (Mr)

    Sum of all the different relative atomic masses (Ar)
  • Calculating mass from moles
    1. Write balanced equation
    2. Calculate moles of reactant
    3. Calculate moles of product
    4. Calculate mass of product
  • Calculating volume from moles
    1. Calculate moles of gas
    2. Use mole equation 2 to find volume
  • Calculating volume from mass
    1. Calculate moles of gas
    2. Use mole equation 2 to find volume
  • Calculating volume of reactant from volume of product
    1. Use balanced equation to find mole ratio
    2. Calculate moles of reactant
    3. Use mole equation 2 to find volume of reactant
  • Calculating percentage yield
    Actual yield / Theoretical yield x 100
  • Calculating percentage purity
    Mass of pure substance / Total mass x 100
  • Empirical formula
    Simplest whole number ratio of atoms in a compound
  • Molecular formula
    Actual number and type of atoms in a compound