Separating Mixtures Flashcards
how do you identify a pure substance
by measuring its melting/boiling point because a pure substance has a specific, sharp melting/boiling point
what happens to the melting point of a solid if an impurity is present
the melting point is lowered
what happens to the boiling point of a liquid if a dissolved impurity is present
it increases the boiling point
what are the differences between a pure substance and a mixture
a pure substance is made up of a single element or compound but a mixture has two or more substances
a pure substances’ compound cannot be changed, but a mixtures can
a pure substance has a specific, sharp melting/boiling point but a mixture melts/boils over a range of temperatures
a compound cannot be separated into its elements using physical processes
why are flat sections seen on a cooling curve when a gas is condensing to liquid or a liquid is freezing to a solid
energy is given out when bonds are formed between the particles which prevents the continuation of cooling
what is a solution
a mixture of a solid substance dissolved in a liquid
what is a solvent
a liquid in which a substance dissolves in to form a solutin
what is a solute
a solid that dissolves in the solvent
what solvents are used to dissolves substances that are insoluble in water
white spirit, ethanol and propanone
what does magnetism do
separates magnetic materials from non-magnetic materials
what does crystallisation do
it separates a soluble solid from its solution
what does filtration do
it separates an insoluble solid from a liquid
what does simple distillation do
separates the solvent from its solution
what does fractional distillation do
separates liquids with different boiling points
what does chromatography do
it separates a mixture of different colours
explain the process of filtration
a filter funnel is lined with filter paper
the mixture is poured through the filter paper
the filter paper only allows liquids to pass through
the insoluble solid is left in the filter paper and the liquid is collected in the beaker below
what is the solid which remains in the filter paper
residue
what is the liquid that passes through the filter paper
filtrate
what are the hazards in filtration
you could slip and fall if some water was spilt on the floor
how do you avoid slipping on water split on the floor during filtration
mop up spillages immediately to reduce the risk of slipping
explain the process of crystallisation
heat the solution slowly using a gentle blue flame until most of the water evaporates
leave the solution in a warm place to cool and crystallise
the remaining solvent will evaporate slowly and crystals will form
dry the crystals between filter papers
how do you get large crystals in crystallisation
heat the solution slowly using a gentle blue flame
do not evaporate all of the water
leave the solution to cool at room temperature so crystals form
what are the hazards in crystallisation
if the solution is heated until too dry, the hot liquid/crystals could spit out from the evaporating basin causing burns
the apparatus will get too hot and could cause a burn if touched
how to avoid hot crystals spitting out in crystallisation
use a gentle blue flame and stop heating before the solution is dry.
Wear safety glasses