Separation Techniques

Question 1

What are separation techniques

Answer 1

physical methods to separate mixtures into their constituents without forming new substances

Question 2

Why are separation techniques important

Answer 2

to obtain pure substances remove impurities and identify substances in food and drugs

Question 3

What methods separate solid liquid mixtures

Answer 3

filtration evaporation to dryness crystallisation simple distillation

Question 4

What methods separate solid solid mixtures

Answer 4

magnetic attraction sublimation filtration after adding solvent

Question 5

What method separates liquid liquid mixtures

Answer 5

separating funnel for immiscible liquids

Question 6

What is filtration

Answer 6

method to separate insoluble solid from liquid

Question 7

What is the process of filtration

Answer 7

mixture poured through filter paper liquid passes as filtrate solid remains as residue

Question 8

What are applications of filtration

Answer 8

separating chalk from water tea strainer removing sand and mud in purification plants

Question 9

What is evaporation to dryness

Answer 9

method to obtain dissolved solid by evaporating all solvent

Question 10

What are applications of evaporation to dryness

Answer 10

production of salt in salt mine removal of water in food preservation

Question 11

What is crystallisation

Answer 11

method to obtain pure well formed crystals from a solution as solubility decreases with temperature

Question 12

What is the process of crystallisation

Answer 12

heat solution evaporate most solvent cool saturated solution filter crystals dry with filter paper

Question 13

What are applications of crystallisation

Answer 13

pure copper sulfate crystals purification crystallisation of microchips

Question 14

What is a disadvantage of evaporation to dryness

Answer 14

solid obtained not always pure soluble impurities remain some solids decompose

Question 15

What is an advantage of crystallisation

Answer 15

impurities remain in solution so pure crystals are obtained

Question 16

When is crystallisation used

Answer 16

to obtain pure salt or solid and prevent thermal decomposition

Question 17

When is evaporation to dryness used

Answer 17

when crystallisation not suitable when solubility of solute does not change or changes little with temperature

Question 18

What is simple distillation

Answer 18

method to obtain pure liquid from solution

Question 19

What is the process of simple distillation

Answer 19

heat solution liquid boils vapour condenses in condenser pure liquid collected as distillate solute remains as residue

Question 20

Why add boiling chips in distillation

Answer 20

to ensure smooth boiling

Question 21

Why place thermometer beside side arm

Answer 21

to measure vapour temperature at boiling point of liquid

Question 22

Why does water enter condenser from bottom

Answer 22

to ensure complete condensation

Question 23

What are applications of simple distillation

Answer 23

obtain pure water from seawater or solutions produce distilled water

Question 24

What is magnetic attraction

Answer 24

method to separate magnetic solids from non magnetic solids

Question 25

What are applications of magnetic attraction

Answer 25

separating iron filings from sulfur separating magnetic materials in scrapyards

Question 26

What is sublimation

Answer 26

process where solid changes directly to gas without liquid state

Question 27

What is the process of sublimation

Answer 27

heat mixture solid sublimes vapour condenses on cold funnel surface pure solid collected non subliming solid remains as residue

Question 28

What are applications of sublimation

Answer 28

separating iodine from sand ammonium chloride from sodium chloride

Question 29

What is filtration after adding solvent

Answer 29

method using solvent where one solid dissolves and the other is insoluble

Question 30

What is the process of filtration after solvent

Answer 30

add solvent stir filter residue is insoluble solid filtrate contains dissolved solid evaporate filtrate to obtain solid

Question 31

What are applications of filtration after solvent

Answer 31

separating sand and sodium chloride

Question 32

What is a separating funnel used for

Answer 32

to separate immiscible liquids that do not dissolve in each other

Question 33

What is the process of separating funnel

Answer 33

mixture forms layers less dense liquid on top open tap to collect bottom layer top layer collected separately

Question 34

What are applications of separating funnel

Answer 34

separating oil and water separating petrol and water

Question 35

What is paper chromatography

Answer 35

method to separate and identify substances in a mixture using a solvent

Question 36

What is the process of paper chromatography

Answer 36

place spot on pencil start line put paper in solvent solvent rises carrying substances at different speeds forming chromatogram

Question 37

Why use a covered container in chromatography

Answer 37

to minimise solvent evaporation

Question 38

What is an application of chromatography

Answer 38

identify unknown substances in mixtures

Question 39

Why draw start line in pencil not ink

Answer 39

ink dissolves and interferes with separation

Question 40

Why must start line be above solvent

Answer 40

to prevent spot dissolving before separation

Question 41

Why must spot not be too large

Answer 41

to prevent overlapping of separated components

Question 42

What is used for colourless substances in chromatography

Answer 42

locating agent that reacts to produce coloured products

Question 43

What is an Rf value

Answer 43

ratio of distance travelled by substance to distance travelled by solvent measured from start line no units constant for a substance