Seperation

Question 1

How do you seperate an insoluble solid from a liquid?

Answer 1

Filtration

Question 2

What happens in filtration?

Answer 2

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

Question 3

What do you need for filtration?

Answer 3

2 test tubes, filter paper, funnel

Question 4

How do you seperate a soluble solid from a solution?

Answer 4

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

Question 5

The solid part of a solution is called…

Answer 5

the solute

Question 6

The liquid part of a solution is called…

Answer 6

the solvent

Question 7

What is filtration used to seperate?

Answer 7

an insoluble solid from a liquid

Question 8

What is evporation used to seperate?

Answer 8

a soluble solute from a solution

Question 9

What is distillation used to seperate?

Answer 9

the solvent from a solution with a soluble solute

Question 10

After distillation, what is the collected liquid called?

Answer 10

distillate

Question 11

What apparatus is needed for distillation?

Answer 11

Thermometer
distillation flask
bung
heat
condenser
beaker

Question 12

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

Answer 12

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

Question 13

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

Answer 13

using fractional distillation

Question 14

What do you need for fractional distillation?

Answer 14

fractionating column, distillation flask, thermometer, condenser, heat

Question 15

How does fractional distillation work?

Answer 15

-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

Question 16

What is the thermometer in fractional distillation used for?

Answer 16

measures the boiling point of the liquid distilling at any moment

Question 17

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

Answer 17

the more volatile liquid

Question 18

what is chromatography?

Answer 18

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

Question 19

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

Answer 19

further

Question 20

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

Answer 20

less far

Question 21

What is a chromatogram?

Answer 21

The result of separating liquids with chromatography

Question 22

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

Answer 22

so the spots don’t dissolve

Question 23

What does Rf stand for?

Answer 23

retardation factor

Question 24

What is the solvent front?

Answer 24

How far it (the solvent) travelled

Question 25

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

Answer 25

more

Question 26

How do you calculate Rf value?

Answer 26

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

Question 27

What is recrystallisation?

Answer 27

The method of purifying a solid and seperating any impurities

Question 28

How does recrystallisation work?

Answer 28

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

Question 29

What is a seperating funnel used to seperate?

Answer 29

two immiscible liquids

Question 30

What is fractional distillation used to seperate?

Answer 30

two miscible liquids

Question 31

(in chromatography) the mobile phase is...

Answer 31

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

Question 32

(in chromatography) the stationary phase is...

Answer 32

the paper

Question 33

What is the difference between fractional distillation and normal distillation

Answer 33

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.

Question 34

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

Answer 34

Because the salt won't evaporate

Question 35

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

Answer 35

Insoluble, filtration

Question 36

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

Answer 36

benzoic acid salt water

Question 37

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

Answer 37

boiling tube to dissolve acid filter paper to filter sand hot funnel to keep benzoic acid dissolved heat to keep it hot

Question 38

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

Answer 38

soluble

Question 39

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

Answer 39

Benzoic acid will recrystallise out

Question 40

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

Answer 40

To help the formation of crystals

Question 41

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

Answer 41

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

Question 42

What is another name for the second stage of recrystallisation?

Answer 42

Buchner filtration

Question 43

What happens when a mixture is heated in simple distillation?

Answer 43

The solvent leaves the solution

Question 44

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

Answer 44

The substance with the highest boiling point

Question 45

What is the best definition of a pure substance?

Answer 45

A substance that consists of only one element or compound

Question 46

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

Answer 46

crystallisation

Question 47

What is an azeotropic mixture?

Answer 47

Two liquids that can't be seperated with simple distillation