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State symbols
s = solid, l = liquid, g = gas, aq = aqueous (dissolved in water)
How to calculate relative formula mass (Mr)
Add up relative atomic masses (Ar) from all elements present
What is a mole
The measure of amount of a substance.
The mass of 1 mole of a substance is the Mr of the substance in g
(Mr water = 18, mass of 1 mol water = 18g)
What is the formula that links mass moles and mr
Mass = moles x mr
How to calculate the % of an element in a compound
Mass of element / molecular mass x 100
How to calculate % yield
Actual produced / theoretical x 100
How to find the formula of a metal oxide experimentally
Weigh crucible and lid
Repeat with mg (metal) inside
Heat crucible with lid until mg burns
Lift lid occasionally
Stop heating when no further sign of reaction
Cool and reweigh
Calculate mass of magnesium oxide
Finding formula of salt containing water of crystallisation
Weigh crucible
Weigh crucible with hydrated copper sulphate
Heat crucible gently to drive off water (Blue —> white)
Allow to cool
Reweigh
Table
Empirical formula
Simplest whole number ratio of atoms present in a compound.
Molecular formula
Actual number of atoms of each element present in a compound
How to calculate molecular and empirical formula from experimental data
Mass mr moles table
Divide each mole vale by the smallest
Round to nearest whole number
This gives you empirical
If given Mr you can use this to work out molecular formula
Note 
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