C2.1 - Purity And Separating Mixtures Flashcards
what is a pure material
a material that is composed of only one type of particle with distinct chemical properties
what is a mixture
two or more pure substances in which each pure substance retains its individual chemical properties
what is an alloy
a mixture of (at least) 2 elements, one of which is a metal
what are some properties of an alloy
strong, malleable, corrosion resistant
where are the atoms in an alloy
in an alloy, the atoms of the second element fit into the spaces between the metal atoms
what molecules does pure water contain
pure water contains water molecules
what atoms does pure gold contain
pure gold contains gold atoms
where are the atoms in a normal metal
in a normal metal, the atoms are arranged, in a regular structure
why are most alloys stronger than metals
because the layers in alloys cannot slide over each other easily (because of the arrangement of atoms in an alloy)
how can you check the purity of a substance
by comapring the boiling point of the substance to the specific boling point at room temperature
what causes the substnace to boil at a different temperature
any impurities cause the substance to boil at different temperature
what is a solution
a solute dissolved in a solvent
what is a solute
a substance that is dissolved in a solvent
what is a solvent
a liquid in which chemical dissolve to make a solution (e.g. water, ethanol)
what is an aqueous solution
a solution where the solvent is water
what happens in filtration
a solid is separated from a liquid (e.g. copper oxide in copper sulfate solution)
what happens in crystallisation
a solvent is evaporated off to leave behind) a solute in crystal form (e.g. salt in water
what happens in distillation
two liquids with significantly different boiling points are separated i.e. when heated, the liquid with the lowest boiling point evaporates first and the vapour is condensed and collected
what happens in fractional distillation
a mixture of liquids with different boiling points are separated (e.g. petrol from crude oil)
what happens in chromatography
substances in a mixture are separated using a stationary phase and a mobile phase
what is a stationary phase
a fixed absorbant material e.g. paper (used for simple paper chromatography), or gel on a solid plate (for thin layer chromatography)
what is a mobile phase
the solvent which carries the soluble compounds of the mixture
what is paper chromatography useful for
paper chromatography is useful for separating mixtures of dyes in solution (e.g. dyes in ink)
is thin layer chromatography or paper chromatography more accurate
thin layer chromatography is more accurate
