Amount of Substance

Amount of Substance

1. Relative masses

   • Relative atomic mass
     • The average mass of one atom of an element/1/12th the mass of an atom of C12
   • Relative molecular mass
     • Average mass of one molecule/1/12th the mass of an atom of C12
   • Relative formula mass
     • (For Ionic compounds) Average mass of one ionic compund/1/12 the mass of C12

2. Avogadro's constant

   • The number of atoms in 1g of hydrogen is 6.022 x 10^23
   • Definition: The number of atoms in 12g of carbon 12.
   • The mole contains this number of particles

3. Number of moles

   • n = m/Mr
   • n = c x v
   • n = vol x 24
   • n = PV/Rt

4. Formula

   • Empirical Formula
     • 1) Atoms 2) Mass 3) Moles 4) Ratio 5) Formula
   • Molecular Formula
     • Divide actual Mr by the Mr of the empirical formula

5. Ionic Equations

   • Get rid of spectator ions

6. Balencing equations

   • Fractions can be used for gasses, make sure numbers add up on both sides