Topic 1 - The mole and reacting masses

SOME REVISION QUESTIONS

• A mole of any element is its relative atomic mass in grams. 
• So, for instance, a mole of magnesium which has an Ar = 24 is 24g. 
• There are 0.18 moles in 7.2g of calcium ( 7.2/40 = 0.18).

MOLES OF COMPOUND

• The mole of any compound is its relative molecular mass in grams. So a mole of water is 18g. 
• An ionic compound possesses no molecules and therefore cannot have a relative molecular mass. Of course, it does possess a formula, and this is taken to be the ‘molecule’. We refer to this as the relative formula mass. 

CALCULATING THE SIMPLEST FORMULA

• The stages in the calculation:
  • 1) Divide…