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Science Revision > Seperation > Flashcards

Seperation Flashcards

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1
Q

How do you seperate an insoluble solid from a liquid?

A

Filtration

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2
Q

What happens in filtration?

A

The liquid filtrate passes through, and the undissolved residue is left on the paper

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3
Q

What do you need for filtration?

A

2 test tubes, filter paper, funnel

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4
Q

How do you seperate a soluble solid from a solution?

A

Depends on what you want. If you want the solid, use EVAPORATION. if you want the liquid, use DISTILLATION

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5
Q

The solid part of a solution is called…

A

the solute

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6
Q

The liquid part of a solution is called…

A

the solvent

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7
Q

What is filtration used to seperate?

A

an insoluble solid from a liquid

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8
Q

What is evporation used to seperate?

A

a soluble solute from a solution

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9
Q

What is distillation used to seperate?

A

the solvent from a solution with a soluble solute

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10
Q

After distillation, what is the collected liquid called?

A

distillate

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11
Q

What apparatus is needed for distillation?

A 
Thermometer
distillation flask
bung
heat
condenser
beaker
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12
Q

What equipment do you use to seperate two immiscible liquids, and what everyday object could you compare this to?

A

using a seperating funnel (like a gravy jug, but more scientific)

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13
Q

How do you seperate a liquid from a mixture of miscible liquids?

A

using fractional distillation

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14
Q

What do you need for fractional distillation?

A

fractionating column, distillation flask, thermometer, condenser, heat

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15
Q

How does fractional distillation work?

A

-The mixture is heated in a flasks
-The mixture boils and vapours from both liquids pass into the fractionating column.
there is a higher proportion of the substance with the lower boiling point.
In the columnn they condense and reboil repeatedly, each time with a higher proportion of the more liquid with the lower boiling point.
-the vapour from the liquid with the lower boiling point emerges from the column first in a pure state and pass into the condenser

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16
Q

What is the thermometer in fractional distillation used for?

A

measures the boiling point of the liquid distilling at any moment

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17
Q

(fractional distillation) the liquid with the lower boiling point is called the more ___ liquid

A

the more volatile liquid

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18
Q

what is chromatography?

A

A method of separating several solids in a mixture such as dyes

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19
Q

In chromatography, how far will solutes with larger rf values travel?

A

further

20
Q

In chromatography, how far will solutes with smaller rf values travel?

A

less far

21
Q

What is a chromatogram?

A

The result of separating liquids with chromatography

22
Q

In chromatography, why must the water be below the spots?

A

so the spots don’t dissolve

23
Q

What does Rf stand for?

A

retardation factor

24
Q

What is the solvent front?

A

How far it (the solvent) travelled

25
Q

What moves quicker up chromatography paper? More soluble solids, less or neither?

A

more

26
Q

How do you calculate Rf value?

A

Distance moved by pigment / distance moved by the solvent (pigment origin to solvent front)

27
Q

What is recrystallisation?

A

The method of purifying a solid and seperating any impurities

28
Q

How does recrystallisation work?

A

The solid is dissolved in the minimum amount of hot solvent. it is then filtered to remove any insoluble impurities. The solution is then cooled and the solid crystallizes out of the liquid.
The mixture is filtered again to obtain the solid which is washed with a little cold solvent

29
Q

What is a seperating funnel used to seperate?

A

two immiscible liquids

30
Q

What is fractional distillation used to seperate?

A

two miscible liquids

31
Q

(in chromatography) the mobile phase is…

A

the solvent that moves through the paper carrying the solutes with it

32
Q

(in chromatography) the stationary phase is…

A

the paper

33
Q

What is the difference between fractional distillation and normal distillation

A

Fractional distillation is used when both liquids will evaporate at the same time, and uses a fractionating column. Distillation can be used for a solid + liquid or two liquids with widely different boiling points.

34
Q

Why don’t you need a fractionating column for seperating salt from water?

A

Because the salt won’t evaporate

35
Q

What type of impurities does the first stage of recrystallisation remove, and what method does it use?

A

Insoluble, filtration

36
Q

For the recrystallisation practical, what type of acid, solute solvent do you use

A

benzoic acid
salt
water

37
Q

What equipment do you need for recrystallisation and what is each used for?

A

boiling tube to dissolve acid

filter paper to filter sand

hot funnel to keep benzoic acid dissolved

heat to keep it hot

38
Q

What type of impurities does the second stage of recrystallisation remove, and what method does it use?

A

soluble

39
Q

What will happen when a mixture containing benzoic acid, salt and water is cooled, and how do you do this?

A

Benzoic acid will recrystallise out

40
Q

In the second stage of recrystallisation why do you need a glass rod?

A

To help the formation of crystals

41
Q

In the second stage of recrystallisation how do you check your recrystallised benzoic acid is pure?

A

Wash w/ cold water- salt on the acid will dissolve
benzoic acid can only dissolve at higher temperatures

42
Q

What is another name for the second stage of recrystallisation?

A

Buchner filtration

43
Q

What happens when a mixture is heated in simple distillation?

A

The solvent leaves the solution

44
Q

A mixture of substances in heated in fractional distillation. Which is collected at the bottom of the column?

A

The substance with the highest boiling point

45
Q

What is the best definition of a pure substance?

A

A substance that consists of only one element or compound

46
Q

What method is used to obtain copper sulfate crystals from copper sulfate solution?

A

crystallisation

47
Q

What is an azeotropic mixture?

A

Two liquids that can’t be seperated with simple distillation

Science Revision (59 decks)

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