3. Compounds, Formulae and Equations

• Moles, mass and Mr

  Moles = mass/Mr
• Moles and volume at RTP

  Moles = volume(dm^3)/24
• Ideal gas equation


  pv=nRT
• Unit of temperature in the ideal gas equation

  Kelvins, K
• Unit of pressure in the ideal gas equation

  Pascals
• Concentration, moles and volume

  Moles = concentration x volume(dm^3)
• Unit of volume in the ideal gas equation


  M^3
• Avagadro’s constant


  6.02 x10 23
• 1dm^3 = 1000cm^3 = 100000m^3
• Degrees Celsius to degrees

  Kelvin

  +/- 273
• Kelvins are used as an alternative unit of measurement for temperature.
• Percentage yield

  (actual yield / theoretical yield) x 100
• Atom economy

  (Sum of molar masses of desired products / sum of molar masses of all products) X 100
• Nitrate


  NO3 -
• Carbonate 


  CO3 2-
• Sulphate

  SO4 2-
• Hydroxide

  OH -
• Ammonium ion


  NH4 +
• Ammonia ion


  NH3 +
• Zinc ion


  Zn 2+
• Silver ion 


  Ag +
• Empirical formula


  The simplest whole number ratio of atoms of each element present in a compound.
• Molecular formula


  The number and type of atoms of each element in a molecule.
• Percentage yield tells you how wasteful a process is. The higher the percentage yield, the more efficient the reaction is.
• Atom economy is a measure of the proportion of reactant atoms that become part off the desired product in the balanced chemical equation.
• Low atom economies means that lots of waste is produced. It cost money to separate the desired product from the waste products and more money to dispose of the waste products safely, so they don't harm the environment.
• Reactant chemicals are usually expensive, and it's a waste of money is a high proportion of them end up as useles prodcuts.
• Reactions with low atom economies are less sustainable. Many raw materials are limited in supply, so it makes sense to use them efficiently so they last as long as possible.