chemical reactions

• theoretical yield - the largest possible mass made in a chemical reaction. using the mole equation.
• actual yield - how much mass, of the desired product, you actually made.
• percentage yield - actual yield / theoretical yield x 100
• reasons why the actual yield may be less than 100 %

  transfer losses - as the chemicals are being transported, some may spill.

  reversible reactions.

  unwanted side products

  impure reactants.
• atom economy - how efficient the reaction is,, and how many atoms are in the desired product compared to how many atoms there are in the reactants [that you started with]
• atom economy equation

  total mass of desired product / total mass of reactants x 100

  [mass = Mr or Ar]
• 100 % atom economy means that all the atoms in the reactants have been turned into desired products. the higher the atom economy, the " greener " the process.
• molar volumes


  moles = volume / 24

  volume is in dm3
• cm3 to dm3

  to go from cm to dm, divide by a thousand. to go from dm to cm, multiply by a thousand
• molar volume - the volume occupied by one mole of any substance at room temperature and pressure
• molar volume of gas at room temperature and pressure is 24 dm3
• RTP - room temperature and pressure, 20 degrees celsius, 1 atmosphere
• volume = moles x 24
• moles = volume / 24
• why can the theoretical mass of a product be calculated if you know the mass of everything else?

  due to the law of conservation of mass, the mass before the reaction will be the same as the mass after the reaction as no atoms are created or destroyed.
• factors to be considered when choosing a reaction pathway?

  • percentage yield
  • atom economy
  • usefulness of by - products
  • rate of reaction
  • position of equilibrium (if the reaction is reversible)
  • availability and cost of reactants
• how can rate of reaction be calculated?

  rate of reaction = amount of product formed or amount of reactant used / time
• concentration = mass / volume
• concentration = moles / volume
• molar volume = gas volume / number of moles
• volume = moles x 24