separation techniques

Question 1

filtration

Answer 1

used to separate insoluble solid form liquid. it involves passing the mixture through filter paper on a funnel. physical

Question 2

filtrate

Answer 2

liquid which has passed through filter

Question 3

residue

Answer 3

particles which are left behind on the filter

Question 4

evaporation to dryness

Answer 4

physical. the soluble solid can be seperated from its solution by evaporating the solvent away by heating. this method is not used to recover solutes that are easily damaged/decomposed by heating, e.g. sugar.

Question 5

crystallization

Answer 5

to separate soluble solid from its solution by evaporating some of the solvent to obtain a saturated solution. this method can be used for substances that decompose when heated to dryness, e.g. sugar. physical.

Question 6

seperation techniques

Answer 6

crystallization
evaporation to dryness
filtration
simple distillation
fractional distillation
separating funnel
chromatography
use of magnet

Question 7

simple distillation

Answer 7

used to separate a single liquid from a solution. the solution is heated to boil off the solvent. the solvent vapour is cooled down and condensed in a Liebig condenser. the liquid obtained is distillate.

Question 8

where is the thermometer placed in distillation?

Answer 8

bulb at the inlet at the condenser, not touching liquid. to measure temperature of vapour entering condenser.

Question 9

what is the purpose of boiling chips?

Answer 9

to ensure smooth boiling

Question 10

why must water enter from the bottom in a Liebig condenser?

Answer 10

the coldest part of the condenser is just before the vapour escapes.
the entire jacket is filled with water

Question 11

fractional distillation

Answer 11

used to separate two or more liquids miscible with one another. components must have different boiling points. liquid with lowest boiling point will be distilled over first.

Question 12

fractional distillation vs simple distillation

Answer 12

fractional distillation has a fractionating column while simple distillation does not

Question 13

what does a fractionating column look like?

Answer 13

packed with glass beads or unreactive substance

Question 14

function of a fractionating column

Answer 14

ensure that components with different boiling points will leave the column at differnet times. it increases the surface area for vapour to condense.

Question 15

separating funnel

Answer 15

immiscile liquids do not mix and wilil separate into differnet layers in a separating funnel. with careful control, different portions of liquid can be drained off. complete separation can be achieved by sacrificing the liquids at the interface.

Question 16

use of magnet

Answer 16

limited to magnetic materials that can be attracted to a magnet.

Question 17

chromatography

Answer 17

to separate a small mixture of chemicals that are often, but not necessarily, coloured. if the chemicals/substances are colourless, a chemical can be sprayed on the chromatogram to make the colourless spots visible. chemical is called a locating agent.

Question 18

why isnt a pen used in chromatography?

Answer 18

pen ink is a mixture that can dissolve in certian solvents and spread up the chromatogram.