separation techniques Flashcards
name the 6 physical methods of separation techniques
filtration evaporation to dryness crystallisation simple distillation fractional distillation chromatography
define soluble
able to dissolve in water
define insoluble
not able to dissolve in water
what is suspension
it is a liquid-solid mixture
another term of solvent
liquid
what does the filtration technique separate
separates insoluble solid from liquid in a liquid-solid mixture
what are residues in a filtration technique
they are insoluble solids
what is the use of filter paper in a filtration technique
to trap residues and allow small substances to pass through
what does the evaporation to dryness technique separate
separates dissolved solids in a solid-liquid mixture
what is left behind in the evaporating dish after heating the solution in evaporation to dryness technique
residues are left behind
why are the residue is left behind in the evaporating dish in the evaporation to dryness technique
that is because it does not decompose on strong heating
what does the crystallisation technique separate
separate solid from a solution
describe the steps of crystallisation
1) when heating, the solution forms a saturated solution (very concentrated)
2) let it cool, pure crystals will appear
3) filter to obtain the crystals
4) wash crystals with cold distilled water then dry between filter papers
what happens to the solids that are soluble in liquid upon heating in a crystallisation technique
solids that are soluble in liquid decompose on strong heating
why wash crystals in cold distilled water in a crystallisation technique
to remove impurities
what does it mean to decompose in a crystallisation technique
breaks down into sugar only
decompose sugar is carbon+water
define miscible
liquids that can mix together
for eg ethanol+water
define immiscible
liquids that cannot mix together
for eg oil+water
what does the simple distillation technique separate
separate pure liquid from a solid-liquid mixture? liquid-liquid mixture
what does a thermometer used for in a simple distillation
to measure the temperature of hot vapour entering the condenser
how to know if the liquid in the colonial flask is pure in a simple distillation technique
if the thermometer reading remain 100-degree celsius throughout
what is the use of boiling chips in a simple distillation technique
ensure smooth and even boiling
why is a round bottom flask used in a simple distillation technique
ensure even heating of the solution
what is the use of a condenser in a simple distillation technique
provides a cool environment for vapour to condense to water
why does the volume of distillate collected reduce in a simple distillation technique
this is because some of the hot vapour will escape the condenser instead of condensing it into the beaker
why does the ´water in´ in the condenser against gravity in a simple distillation technique
as it is efficient in condensing the water vapour and
the water stays longer in the condenser as it is against gravity
what does the fractional distillation technique separate
separate liquid in a solution
what is the use of glass beads in a fractional column in a fractional distillation technique
provides large surface area so that vapour can undergo repeated condensation and boiling
which liquid will distil first?
the highest or lowest boiling point
lowest boiling point
why is the condenser sloping downwards
to make sure that the pure solvent can run into the beaker
explain how the fractional column works
vaporization occurs first
the LBP rise up into consider and condenses into liquid and collect as distillate
while LBP is collected, condensation occurs
water vapour of HBP condenses and drops back into the flask
after LBP is collected, temperature rises rapidly
difference between fractional and simple distillation
1) fractional uses fractional column but simple does not
2) fractional separates miscible liquids but simple separates solvent from a solution
what does the chromatography technique separate
separate small amount of subs from mixture based on different solubilities of components
why is the line drawn by pencil and not pen in a chromatography technique
this is because the pencil is insoluble in the solvent and won’t affect the experiment/ interfere with the result
why is the starting line above solvent in a chromatography technique
to prevent dyes to dissolve into the solvent before the start of the chromatogram
what does it say when a dye moves the furthest
it is more soluble in the solvent
why are the spots far apart on the line
to prevent interference with each other
so as to avoid smudging and overlapping dyes
what does it say when there is no dye on a chromatogram paper
that it does not dissolve in the solvent
aka it is insoluble
what does it say when there is one spot on a chromatogram paper
it means that the substance is pure
how does the solvent separate the components in the sample
the solvent dissolves the component
the more soluble the component is, the further it travels
