Amount of Substance Revision

Amount of substance is a quantity used to count the number of particles in a substance, measured in moles. One mole is the amount of substance that contains 6.02 x10^23 particles. The Avogadro Constant is 6.02x10^23 mol-1, the number of particles in each mole of carbon-12. 12g of carbon-12 contains 6.02x10^23 atoms. Mass of one mole of any element is the relative atomic mass in grams. E.g. one mole of iron has a mass of 55.8g. 

Molar mass gives the mass in grams in each mole of the substance. Molar mass is the mass per mole of a substance, the units are gmol-1. 

mass = molar mass x moles

Molecular Formula- this is the number of atoms of each element in a molecule. 

Empirical formula- this is the simplest whole-number ratio of atoms of each element in a compound.

Relative molecular mass Mr - compares the mass of a molecule w the mass of an atom of carbon-12. Calculates by adding up the  relative atomic massesof the elements in a molecule. 

Relative formular mass - compares the mass of a formula unit w the mass of an atom of carbon-12. Calculated by adding the relative atomic masses of the elements in the empirical formula. 

Analysis- investigating the chemical composition of a substance. 

Hydrates salts- many coloured salts are hydrated, water molecules are part of their crystalline structure. This is known as water of crystallisation. When blue crystals of hydrated copper (II) sulfate are heated, bonds holding the water within the crystal are broken and water is driven off, this leaves behind white anhydrous copper (II) sulfate. 

CuSO4.5H2O -> CuSO4 +5H2O

Assumptions…