AQA GCSE Chemistry - Equations

Avogadro's number

There are 6.02 x 10²³ particles of a substance in 1 mole.

The mole

moles = mass/relative atomic mass

Concentration in g/dm³

concentration = mass (g)/volume (dm³)

Concentration in mol/dm³

concentration = moles (mol)/volume (dm³)

or

moles = concentration x volume (in dm³)

Gas volumes

1 mole of any gas has a volume of 24dm³

volume (dm³) = moles x 24dm³

Converting from cm³ to dm³

1dm³ = 1000cm³

Percentage Yield

(mass of product actually made/maximum theoretical mass of product) x 100

Atom Economy

(relative formula mass of desired product from equation/sum of relative formula masses of all reactants from equation) x 100

Calculating energy changes

Energy change in a reaction = Total energy needed to break the bonds in reactants - Total energy released when bonds in the products are formed

Rate of reaction

mean rate of reaction = quantity of reactant used/time taken

mean rate of reaction = quantity of product formed/time taken

(Quantity usually measured as a mass or volume)

Chromatography

Distance moved by substance/distance moved by solvent