2.1.3 - amount of substance

• the symbol for amount of substance is ’ n ‘
• Moles (mol) = mass (g) / molar mass (g mol -1)
• Avogadro’s law is that under the same temperature and pressure, one mole of any gas would occupy the same volume.
• A gas occupies 24 dm3 or 24000 cm3 volume at room temp and pressure
• Molar gas volume is the volume per mole of gas molecules
• Different gas partices occupy the same volume because the gas particles are very spread out hence indivdual differences have no effect.
• The ideal ways in which gases behave is that they are in continuous motion

  experience no intermolecular forces

  exert pressure when they collide with each other or container

  no kinetic energy is lost in the collisions

  when temperature increases, kinetic energy of gases also increases
• Ideal gas equation:

  pV = nRT

  pressure (Pa) x volume (m3) = moles (mol) x gas constant (8.314 J mol-1) x temperature (K)
• 1 atmospheric pressure = 101325 Pa
• 0 degrees = 273 Kelvin
• Concentration of a solution is the amount of solute dissolved in 1dm3 of solvent
• A standard solution is a solution of known concentration
• Dilute - small amount of solute per dm3 of solvent
• A species in a chemical reaction is any particle that takes part in a reaction
• The four state symbols are

  solid (s)

  liquid (l)

  gaseous (g)

  aqueous (aq)
• Percentage yield is the efficiency of which reactants are converted into products
• Percentage yield is not always 100% because

  reaction may be at equilibrium

  the reactants may be impure

  side reactions could happen

  reactants or products may be left behind while transferring

  loss of products during separation and purification
• Percentage yield =

  ( actual amount of product / theoretical amount of product ) x 100
• Atom economy = ( mr of desired product / sum of mr of all products ) x 100
• Addition reactions have 100% atom economy because two or more reactants are combined to form one desired product