Empirical formula

Empirical formula

1. Molecular formula

   • actual ratio in which atoms combine
   • relative Molecular mass (Mr)
     • can be found using mass spectrometer
     • is equal to sum of relative atomic mass (Ar) of all the atoms
       • relative atomic mass (Ar) is the mass of atom as compared to carbon-12 atom
   • simple multiple (n) of emperical formula
     • n = relative molecular mass (Mr) / emperical mass
       • molecular formula = n x emperical formula

2. simplest ratio in which atoms combine

3. empirical mass

4. can be found by experiment

   • steps
     • find the ratio of actual mass of elements
     • convert mass ratio to mole ratio
       • no of moles = given mass / mass of 1 mole
     • reduce mole ratio to simplest ratio
     • write empirical formula from simples mole ratio