AQA GCSE – CHEMISTRY - COMBINED: TRIOLOGY
Mixtures
There are different ways to separate mixtures, such as filtration, crystallisation, simple
distillation, fractional distillation and chromatography. The method chosen depends on the
type of mixture.
Pure substances and mixtures
The meaning of pure
The word 'pure' is used in chemistry in a different way from its everyday meaning. For
example, shops sell cartons labelled as ‘pure' orange juice. The label means that the contents
are just orange juice, with no other substances added. However, the juice is not pure in the
chemical sense, because it contains different substances mixed together. In chemistry:
• a pure substance consists only of one element or one compound
• a mixture consists of two or more different substances, not chemically joined together
The substances in a mixture can be elements, or compounds, or both. Being part of a mixture
does not change the chemical properties of the substances that are in it.
Separating mixtures
Mixtures can be separated by physical processes. These processes do not involve chemical
reactions, and no new substances are made.
Filtration and crystallisation
Filtration
Filtration is used to separate an insoluble solid from a liquid. It is useful for separating sand
from a mixture of sand and water, or excess reactant from a reaction mixture.
, Filtration works because the filter paper has tiny holes or pores in it. These are large enough
to let small molecules and dissolved ions through, but not the much larger particles of
undissolved solid.
Filtration:-
Method used to separate an insoluble solid from a liquid using a physical barrier such as
paper.
Insoluble:-
Unable to dissolve in a particular solvent. For example, sand is insoluble in water.
Excess:-
In chemistry, a substance is in excess if there is more than enough of it to react with another
reactant.
reactant:-
A substance that reacts together with another substance to form products during a
chemical reaction.
Molecules:-
A collection of two or more atoms held together by chemical bonds.
Dissolved:-
A substance is said to be dissolved when it breaks up and mixes completely with a solvent to
produce a solution.
ions:-
Electrically charged particle, formed when an atom or molecule gains or loses electrons.
Separating insoluble solids
1. One beaker contains a mixture of solid and liquid, the other contains a funnel with
filter paper
Mixtures
There are different ways to separate mixtures, such as filtration, crystallisation, simple
distillation, fractional distillation and chromatography. The method chosen depends on the
type of mixture.
Pure substances and mixtures
The meaning of pure
The word 'pure' is used in chemistry in a different way from its everyday meaning. For
example, shops sell cartons labelled as ‘pure' orange juice. The label means that the contents
are just orange juice, with no other substances added. However, the juice is not pure in the
chemical sense, because it contains different substances mixed together. In chemistry:
• a pure substance consists only of one element or one compound
• a mixture consists of two or more different substances, not chemically joined together
The substances in a mixture can be elements, or compounds, or both. Being part of a mixture
does not change the chemical properties of the substances that are in it.
Separating mixtures
Mixtures can be separated by physical processes. These processes do not involve chemical
reactions, and no new substances are made.
Filtration and crystallisation
Filtration
Filtration is used to separate an insoluble solid from a liquid. It is useful for separating sand
from a mixture of sand and water, or excess reactant from a reaction mixture.
, Filtration works because the filter paper has tiny holes or pores in it. These are large enough
to let small molecules and dissolved ions through, but not the much larger particles of
undissolved solid.
Filtration:-
Method used to separate an insoluble solid from a liquid using a physical barrier such as
paper.
Insoluble:-
Unable to dissolve in a particular solvent. For example, sand is insoluble in water.
Excess:-
In chemistry, a substance is in excess if there is more than enough of it to react with another
reactant.
reactant:-
A substance that reacts together with another substance to form products during a
chemical reaction.
Molecules:-
A collection of two or more atoms held together by chemical bonds.
Dissolved:-
A substance is said to be dissolved when it breaks up and mixes completely with a solvent to
produce a solution.
ions:-
Electrically charged particle, formed when an atom or molecule gains or loses electrons.
Separating insoluble solids
1. One beaker contains a mixture of solid and liquid, the other contains a funnel with
filter paper
