amount of substance

• unit to measure amount of substance

  mole
• avogadros constant represents


  number of atoms per mole of the carbon-12 isotope
• mass of 1 mole = relative atomic mass in grams
• moles (mol) = mass(g) / molar mass(gmol-1)
• avogadros law


  under the same temperature and pressure, one mole of any gas would occupy the same volume
• molar gas volume


  the volume per mole of gas molecules
• different gas particles occupy the same volume because the gas particles are very spread out so individual differences has no effect
• moles (mol) = volume (dm3) / 24

  or

  moles (mol) = volume (cm3 / 24000
• ideal ways in which gases behave:

  • they are in continuous motion

  • no intermolecular forces experienced

  • exert pressure when they collide with eachother or container

  • no kinetic energy is lost in the collisions

  • when temperature increases, kinetic energy of gases also increase
• ideal gas equation


  pV=nRT

  pressure (Pa) x volume (m3) = number of moles (mol) x gas constant (8.314Jmol-1) x temperature (K)
• 1 atmospheric pressure (atm) is 101325 Pa
• 0°C is 273K
• concentration of a solution is the amount of solute dissolved in 1dm3 of solvent
• moles (mol) = concentration (moldm-3) x volume (dm3)
• a standard solution is a solution of known concentration
• steps to prepare a standard solution:

  1. weigh the solute using the weigh by difference method
  2. in a beaker dissolve the solute using the solvent
  3. pour the solution into a volumetric flask
  4. rinse the beaker using the solution and add it to the flask
  5. add solvent to the flask carefully until it reaches the graduation line
  6. mix the solution thoroughly to ensure complete mixint
• concentrated - large amount of solute per dm3 of solvent

  dilute - small amount of solute per dm3 of solvent
• a species in a chemical reaction is any particle that takes part in a reaction
• percentage yield is 


  the efficiency of which reactants are converted into products
• reasons for not getting 100% yield:

  1. reaction may be at equilibrium
  2. reactants may be impure
  3. side reactions could happen
  4. reactants or products may be left behind while transferring
  5. loss of products during separation and purification
• percentage yield = (actual amount of product (mol) / theoretical amount of product (mol)) / 100
• atom economy tells us the proportion of desired products compared with all the products formed in the reaction
• atom economy = (molecular mass of desired product / sum of the molecular masses of all products) x 100
• 100% yield doesnt mean 100% atom economy because not all products of the reactants will be the required products
• addition reactions have 100% atom economy