Composition & yield

Theoretical yield

maximum amount of product that can be made

Actual yield

The amount of product made by carrying out the reaction

Percentage yield equation

Actual yield/theoretical yield x 100

Reasons % yield is less than 100%

Reversible reaction, product is lost, side reactions

Reversible reaction

A chemical reaction in which the products re-form the original reactants

Ways product is lost

Stuck in the reaction vessel, or by separation from the reaction mixture

Side reactions

Reactions that do not give the desired product of a reaction

Use of percentage yield

To measure the efficiency of a reaction

Molecular formula

A chemical formula that shows the number and kinds of atoms in a molecule, but not the arrangement

Empirical formula

a chemical formula showing simplest ratio of elements in a compound

Hydrated

A crystal containing water molecules

Anhydrous

A crystal which doesn't contain any water molecules

Heating to constant mass

Heating and weighing, and repeating this until two readings are the same

Thermal decomposition

The breakdown of a compound by heat

Determining waters of crystallisation

Heat hydrated compound to constant mass