separation and purification
practial work in the lab involves
materials -apparatus -methods
solvent
substance that dissolves a solute
solute
substance that dissolves in a solvent
solution
a mixture of one or more solutes and solvents
solubility
the amount of solution that dissolves in 100ml of water at a set temperature
making a saturated solution
solubility increases with temperature a solution is saturated when no more solute can dissolve at that temperature
method to separate a solid from a liquid
filtering to remove solids -crystallisation to obtain solids from its solution -evapouration to remove all solvent
method to separate two solids
find solvent that can only dissolve one solid - add solvent -filter mixture -rinse residue -separate remaining solvent from solute
steps to simple distillation
-heat solution on a flask vapour will rise as it boils -condenser is cold and water will condense - water drips into beaker and residue stays in flask
steps in fractional distillation
-heat mixture to lowest boiling point -vapour condenses when it hits the flask -when beads reach the temperature the vapour will no longer condense only the compound with a higher boiling point will -vapour passes to condenser thermometer reads above lower boiling point
uses for fractionall distillation on a large scale
petroleum refining -ethanol production -separate noble gases from air
uses for paper chromaography
-separate substances in a mixture -check substance purity -identify substances in a mixture
how is paper chromatography uses to separate substances in a mixture
a thick black line is drawn on paper -paper is places in beaker with ethanol (line must be above ethanol) -ethanol rises dissolving ink and colour appears on paper
how does paper chromatography separating substances work
-ethanol moves through capillary action -ethanol dissolves substances in ink and they travel with it -each substance travels at different speeds depending on solubility
method to check substance purity using chromotagraphy
-draw pencil line on paper - stand paper in solvent -solvent will rise -if solvent separates into different blocks it is not pure
method to identify substances in a mixture using chromography paper
-make concentrated solution of substances in mixture and mixture -put solutions in propane and draw line above rhem all -solvents will rise -mixture will separate and any substances at the same height are in the mixture
how to use melting or boiling points to check purity
pure substances have a definite boiling points -impure substances have lowet melting points and higher boiling points -impure substances have range in their melting and boiling points
how to increase purity
-rinsing solid product with distilled water -repeat seperation techniques