separation techniques

Question 1

name the 6 physical methods of separation techniques

Answer 1

filtration 
evaporation to dryness 
crystallisation
simple distillation 
fractional distillation 
chromatography

Question 2

define soluble

Answer 2

able to dissolve in water

Question 3

define insoluble

Answer 3

not able to dissolve in water

Question 4

what is suspension

Answer 4

it is a liquid-solid mixture

Question 5

another term of solvent

Answer 5

liquid

Question 6

what does the filtration technique separate

Answer 6

separates insoluble solid from liquid in a liquid-solid mixture

Question 7

what are residues in a filtration technique

Answer 7

they are insoluble solids

Question 8

what is the use of filter paper in a filtration technique

Answer 8

to trap residues and allow small substances to pass through

Question 9

what does the evaporation to dryness technique separate

Answer 9

separates dissolved solids in a solid-liquid mixture

Question 10

what is left behind in the evaporating dish after heating the solution in evaporation to dryness technique

Answer 10

residues are left behind

Question 11

why are the residue is left behind in the evaporating dish in the evaporation to dryness technique

Answer 11

that is because it does not decompose on strong heating

Question 12

what does the crystallisation technique separate

Answer 12

separate solid from a solution

Question 13

describe the steps of crystallisation

Answer 13

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

Question 14

what happens to the solids that are soluble in liquid upon heating in a crystallisation technique

Answer 14

solids that are soluble in liquid decompose on strong heating

Question 15

why wash crystals in cold distilled water in a crystallisation technique

Answer 15

to remove impurities

Question 16

what does it mean to decompose in a crystallisation technique

Answer 16

breaks down into sugar only

decompose sugar is carbon+water

Question 17

define miscible

Answer 17

liquids that can mix together

for eg ethanol+water

Question 18

define immiscible

Answer 18

liquids that cannot mix together

for eg oil+water

Question 19

what does the simple distillation technique separate

Answer 19

separate pure liquid from a solid-liquid mixture? liquid-liquid mixture

Question 20

what does a thermometer used for in a simple distillation

Answer 20

to measure the temperature of hot vapour entering the condenser

Question 21

how to know if the liquid in the colonial flask is pure in a simple distillation technique

Answer 21

if the thermometer reading remain 100-degree celsius throughout

Question 22

what is the use of boiling chips in a simple distillation technique

Answer 22

ensure smooth and even boiling

Question 23

why is a round bottom flask used in a simple distillation technique

Answer 23

ensure even heating of the solution

Question 24

what is the use of a condenser in a simple distillation technique

Answer 24

provides a cool environment for vapour to condense to water

Question 25

why does the volume of distillate collected reduce in a simple distillation technique

Answer 25

this is because some of the hot vapour will escape the condenser instead of condensing it into the beaker

Question 26

why does the ´water in´ in the condenser against gravity in a simple distillation technique

Answer 26

as it is efficient in condensing the water vapour and

the water stays longer in the condenser as it is against gravity

Question 27

what does the fractional distillation technique separate

Answer 27

separate liquid in a solution

Question 28

what is the use of glass beads in a fractional column in a fractional distillation technique

Answer 28

provides large surface area so that vapour can undergo repeated condensation and boiling

Question 29

which liquid will distil first?

the highest or lowest boiling point

Answer 29

lowest boiling point

Question 30

why is the condenser sloping downwards

Answer 30

to make sure that the pure solvent can run into the beaker

Question 31

explain how the fractional column works

Answer 31

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

Question 32

difference between fractional and simple distillation

Answer 32

1) fractional uses fractional column but simple does not

2) fractional separates miscible liquids but simple separates solvent from a solution

Question 33

what does the chromatography technique separate

Answer 33

separate small amount of subs from mixture based on different solubilities of components

Question 34

why is the line drawn by pencil and not pen in a chromatography technique

Answer 34

this is because the pencil is insoluble in the solvent and won’t affect the experiment/ interfere with the result

Question 35

why is the starting line above solvent in a chromatography technique

Answer 35

to prevent dyes to dissolve into the solvent before the start of the chromatogram

Question 36

what does it say when a dye moves the furthest

Answer 36

it is more soluble in the solvent

Question 37

why are the spots far apart on the line

Answer 37

to prevent interference with each other

so as to avoid smudging and overlapping dyes

Question 38

what does it say when there is no dye on a chromatogram paper

Answer 38

that it does not dissolve in the solvent

aka it is insoluble

Question 39

what does it say when there is one spot on a chromatogram paper

Answer 39

it means that the substance is pure

Question 40

how does the solvent separate the components in the sample

Answer 40

the solvent dissolves the component

the more soluble the component is, the further it travels