C2) Amount of substance

• Relative molecular mass (Mr)= Average mass of one molecule/Mass of 1/12th of 12-carbon
• Avogadro constant: 6.022 x 10^23

  It's the number of atoms in 12g of carbon-12
• A mole is the amount of substance that contains 6.022x10^23 particles
• Number of moles= mass (g)/mass of 1 mole (g)
• moles in a solution= conc (mol/dm3) x vol (cm3)/ 1000
• PV= nRT


  P= pressure (Pa)

  V= volume (m3)

  n= number of moles

  R= gas constant (J K-1 mol-1) -8.31

  T= Temperature (K)
• Empirical formula is the simplest whole number ratio of a compound. e.g. C6H12O6 ---> CH6O
• Molecular formula is the actual number of atoms of each element in a molecule.
• % yield= actual mass/theoretical mass x 100
• % atom economy= Mr of desired product/Mr of reactants x 100
• Reasons % yield isn't 100%

  -Reversible reaction

  -Gases lost

  -Solution spilled