Amount of substance

• The relative atomic mass (Ar) is the average mass of an atom of an element relative to 1/12 the mass of an atom of carbon-12.
• The relative molecular mass (Mr) is the mass of a molecule relative to 1/12 the mass of an atom of carbon-12.
• An empirical formula shows the simplest whole number ratio of the atoms of each element in a compound.
• A molecular formula shows the actual number of atoms of each element in one molecule of the substance.
• Chemical reactions involve spectator ions, ions which do not take part in the reaction, meaning the balanced equation can be rewritten as an ionic equation.
• Amount in moles = Mass divided by Mr.
• n= m/Mr
• The Avogadro constant in the number of particles in one mole, it is 6.02 x 10 to the power of 23.
• Mass/Mr = Amount in moles = Number of particles/ Avogadro constant
• m/Mr = n = Number of particles/L
• m = n x Mr
• Mr = n/m
• Solutions contain a solute dissolved in a solvent. The amount in moles can be determined from the solution volume and concentration of solution.
• Amount in moles = Solution volume (cm3) x Concentration (mol dm-3)/ 1000
• n = (vc)/1000
• v = n x 1000/ c
• c = n x 1000/ v
• The ideal gas equation is pV=nRT.

  p = pressure in Pa

  V = volume in m3

  n = amount of moles in mol

  R = gas constant (8.31JK-1 mol-1)

  T = temperature in K
• pv=nRT


  What is the ideal gas equation?
• percentage atom economy = (mass of desired product / mass of all reactants) x 100
• Percentage yield = (actual yield/ theoretical yield)/ 100
• Actual yield = (percentage yield x theoretical yield)/ 100
• Actual yield is defined as the quantity of a product found to be formed in a chemical reaction.
• The theoretical yield is the quantity of the product that should be obtained in the reaction if it goes to completion. It is the maximum product you could get.

  Basically calculate the Mr.
• Developing chemical processes with a high atom economy benefits society and industry by reducing waste, lowering cost (cost effective), improving sustainability and enhancing environmental and economic efficiency.