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Classified Chemistry IGCSE Paper_6_Topic 1

1 - Experimental technique Mostafa Barakat (0100 165 44 62)

1

Topic 1

Laboratory apparatus

Safety in laboratory

Methods of purification

Separation of mixtures

Chromatography





2

(1) June 2002 Q (2_b, c)

2 The label shows the substances present in a bottle of lemon drink.

(b) How could a sample of pure water be obtained from the drink?

............................................................................................................................

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....................................................................................................................... [2]

(c) Describe an experiment you could carry out to show that the drinkcontained two different yellow substances

............................................................................................................................

............................................................................................................................

............................................................................................................................

............................................................................................................................

............................................................................................................................

........................................................................................................................[3]

Heat the lemon drink

condense water vapour (simple distillation)

by chromatography

put the drink on chromatogram paper

add suitable solvent (water of ethanol)

measure the distance moved by solvent





3

(2) June 2003 Q (1)

1 Look at the diagrams of common laboratory apparatus.

A

B

C

D

(a) Complete the empty boxes to identify the pieces of apparatus labelled. [4]

Mortar

Stirrer

Tripod

Bunsen Burner





4

(b) What name is given to the separation method in C?

........................................................................................................................[1]

(c) Which apparatus would be most suitable to obtain crystals from an

aqueous solution of copper(II) sulphate?

............................................................................................................................

........................................................................................................................[1]

(3) June 2003 Q (6)

Beach sand is a mixture of sand and broken shells (calcium carbonate).Calcium carbonate reacts with dilute hydrochloric acid to form a solution ofcalcium chloride.

Plan an investigation to find out the percentage of shell material in a givensample of beach sand.

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........................................................................................................................[6]

Filteration

D liquid is evapourated to obtain crystals

1) take a 10 g of beach sand in a beaker

2) add excess of dilute hydrochloric acid to beach sand

3) filter to remove sand from the solution of calcium chloride

4) wash the sand to remove the traces of solution

5) dry residue (sand)

6) weight the sand

mass of shell = mass of beach sand - mass of sand

% of shell = (mass of shell / mass of beach sand) X 100





5

(4) June 2004 Q (1_a, b)

1 An experiment was carried out to find the pH of samples of soil from a

farmer ’s field

(a) Identify the pieces of apparatus labelled

A, ………………………………………………………………………………………

B, ………………………………………………………………………………………

C, ………………………………………………………………………………………

[3]

(b) Why was the soil crushed?

............................................................................................................................

........................................................................................................................[2]

Funnel

Flask

pipette

to increase the surface area to increase the rate of reaction





6

(5) June 2005 Q (1_a, b)

1 A small piece of limestone was heated strongly and left to cool. A few dropsof cold water were added. The solid expanded and gave off steam.

(a) Complete the empty boxes to identify the pieces of apparatus labelled. [3]

(6) June 2006 Q (2)

2 A sample of orange fruit jam was investigated to check the three colouringspresent.

Step 1 The jam was boiled with water.

Step 2 The mixture was filtered.

Step 3 The filtrate was concentrated.

Step 4 The concentrate was analysed by chromatography.

(a) What was the purpose of Step 1?

........................................................................................................................[1]

(b) Why was the mixture filtered?

........................................................................................................................[1]

(c) How was Step 3 carried out?

........................................................................................................................[1]

(d) Draw a diagram to show the possible paper chromatogram obtained inStep 4.

[2]

clamppipette

Bunsen burner

to extract the colour

to remove solid (insoluble impurites)

heating / evapurate





7

(7) June 2007 Q (1)

1 A mixture of ethanol and water can be separated by fractional distillation.The apparatus below can be used to carry out such a separation in thelaboratory.

(a) Name each piece of apparatus.

A, ………………………………………………………………………………………

B, ………………………………………………………………………………………

C, ………………………………………………………………………………………

[3]

(b) What is the purpose of D?

........................................................................................................................[1]

(c) How could the purity of the ethanol collected be checked?

........................................................................................................................[1]

thermometer

beaker

tripod

to condense the vapour

measure the boiling point





8

(8) June 2007 Q (3)

3 Chromatography can be used to identify amino acids from a sample of protein.The diagram shows the chromatogram obtained when four samples of amino

acids were analysed. The paper was sprayed with ninhydrin.

(a) Why is the origin line drawn in pencil?........................................................................................................................[1]

(b) Which amino acids could possibly be the same?

........................................................................................................................[1]

(c) Which amino acid sample contains more than one amino acid? Explainyour answer.

Sample ………………………………………………………………………………...

Explanation ……………………………………………………………………………

[2](d) Suggest why it is necessary to spray the chromatogram with ninhydrin.

........................................................................................................................[1]

Because it does not dissolve in water

1 and 3

Sample 4

two spots present

to show the position of the acid (spots)





9

(9) June 2008 Q (1_a, c)

1 A solution of copper sulphate was made by reacting excess copper oxidewith dilute sulfuric acid. The diagram shows the method used.

(a) Complete the empty boxes to name the pieces of apparatus. [3](c) Draw a labelled diagram to show how the mixture was filtered

[2]

(10) June 2008 Q (7_b)

7 This label is from a container of ‘Bite Relief’ solution

(b) What practical method could be used to separate the mixture of alcohol(b.p 78°C) and water (b.p 100°C)?

………………………………………………………………………………………………[2]

spatula

tripodmeasuring cylinder

fraction distillation





10

(11) June 2009 Q (1_a, b, ii)

1 A student reacted nitric acid with magnesium oxide to prepare magnesiumnitrate. The diagram shows the procedure followed in three stages.

(a) Complete the boxes to identify the pieces of apparatus labelled. [3](b) (ii) What method is used to remove the unreacted magnesium oxide after stage 3?

........................................................................................................................[1]

(12) June 2009 Q (6_a)

6 Acid base indicatorsIndicators are used to identify acids and bases.Indicators can be obtained from berries and other fruits.(a) Plan an experiment to obtain an aqueous solution of an indicator fromsome berries.

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........................................................................................................................[3]

stirrer

beakerbalance

Filteration

1) Add water

2) Crush berries

3) Heat

4) Filter





11

(13) June 2010 (61) Q (1_a, b)

1 The diagram shows the apparatus used to prepare a gas. The gas is more

dense than air.

(a) Complete the boxes to name the apparatus. [3]

(b) Identify one mistake in the diagram.

....................................................................................................................... [1]

(14) June 2010 (62) Q (1_a, b, c)

1 The diagrams show three sets of apparatus, F, G and H, used to separatethree different mixtures.

(a) Complete the boxes to name the apparatus used. [3]

separating funnel gas jar

flask

gas should be collected downwards

Bunsen burner

condenser

tripod





12

(b) (i) Which apparatus is used to obtain crystals of a salt from a solution of the salt?

....................................................................................................................... [1]

(ii) Which apparatus is used to separate a mixture of coloured dyes?....................................................................................................................... [1]

(15) June 2010 [62] (Q 2)

2 A student investigated the green colour in grass.The student followed these instructions.

1 Cut the grass into small pieces and crush the grass by grinding with sandand ethanol.

2 Decant the liquid.

3 Investigate which colours are present in the green solution.

(a) Name the apparatus used to crush the grass in instruction 1.

....................................................................................................................... [1]

(b) Explain the term decant .

....................................................................................................................... [1]

(c) Outline how the student could carry out instruction 3. You may draw adiagram to help you answer this question.

............................................................................................................................

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[4]

F

G

Pestle and mortar

pour liquid off

1) chromatogram paper

2) apply solution to paper

3) use water as solvent

4) spots at different levels





13

(16) June 2011 [61] Q (1, 3)

1 A student heated hydrated zinc sulfate crystals, ZnSO4.7H2O, using theapparatus below to obtain a sample of water.

(a) Complete the box to identify the piece of apparatus labelled. [1](b) Use labelled arrows to indicate:(i) where the heat is applied,(ii) where the sample of water would collect. [2](c) State the purpose of the ice cubes.

....................................................................................................................... [1]

(d) Describe a physical test for pure water.

test .....................................................................................................................

result ............................................................................................................. [2]

3 The colours present in some fruit sweets can be separated using theapparatus below. The colours are water-soluble dyes.

(a) Name the process used to separate the colours.

....................................................................................................................... [1]

(b) Name the solvent used.

....................................................................................................................... [1]

Beaker

to cool the water or steam

boiling point

100 C

chromatography

water





14

The results obtained for the colours in two different sweets, C and D, areshown below.

(c) What is the name for the line at position B?

....................................................................................................................... [1]

(d) What conclusions can you draw about the colours present in sweets C and D?

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....................................................................................................................... [3]

(17) June 2011 [62] Q (1_a, b)1 A student separated an aqueous solution of sodium chloride.She measured out 70 cm3 of the solution and then obtained pure water fromthe solution.

(a) Which of these pieces of apparatus is most suitable to measure 70 cm3 of the solution?

Tick one box.

[1]

Base line

sweet C has 4 colours

sweet D has 3 colours





15

(b) (i) Complete the empty boxes to name the pieces of apparatus below

(ii) Which method of separation, A, B or C, would be most suitable to obtainpure water from the solution?

apparatus ...................................................................................................... [1]

(c) Describe how crystals of sodium chloride could be quickly obtained fromthe solution.

............................................................................................................................

............................................................................................................................

....................................................................................................................... [2]

condenser

evapourating dish

tripod

A Distillation

heat to crystallizing point until saturated





16

(18) June 2012 [61] Q (1_a, c)

1 A student reacted excess iron powder with sulfuric acid to prepare a solutionof iron(II) sulfate. The diagram shows the procedure followed in three stages.

(a) Complete the boxes to identify the pieces of apparatus labelled. [2]

(c) Describe the effect of boiling the solution of iron(II) sulfate for severalminutes .

....................................................................................................................... [3]

(19) June 2012 [61] Q (3)

(3) Coffee beans contain caffeine and other compounds. Caffeine is soluble inwater and in trichloromethane, an organic solvent. A student obtained crystalsof caffeine by the following method.

Stage 1 some coffee beans were crushed into small pieces. Stage 2 Hot

water was added to the crushed beans to dissolve the soluble substances.Stage 3 the crushed beans were separated from the liquid solution.Stage 4 the liquid was allowed to cool and shaken with trichloromethane to extract thecaffeine from the water .Stage 5 the caffeine was crystallised from the trichloromethane solution.Stage 6 the caffeine crystals were checked for purity.

(a) What apparatus should be used to crush the beans in Stage 1?

....................................................................................................................... [2]

(b) How could the dissolving process in Stage 2 be speeded up?

....................................................................................................................... [1]

spatula

tripod

1) evapourating of water 2) crystals formed 3) colour goes brown

pestle and mortar

stir / mix / shake





17

(c) Draw a diagram of the apparatus used in Stage 3. [2]

(d) How should Stage 5 be carried out?....................................................................................................................... [2]

(e) What method could be used to check the purity of the crystals in Stage 6?

....................................................................................................................... [1]

heat to crystallizing point in fume cupboard

melting point / chromatography





18

(20) Nov 2001 Q (1_a)

1 The diagrams show the apparatus used to find the concentration of a nitricacid solution. 25.0 cm3 of nitric acid was added to a flask.Sodium hydroxide was added to the acid until the solution was neutral. The

volume of the sodium hydroxide was noted.

(a) Complete the boxes to name the apparatus used.[3]

beaker

pipette

burette





19

(21) Nov 2002 Q (1_a, b)

1 A student investigated the neutralization of dilute hydrochloric acid, using anexcess of calcium carbonate.

(a) Identify the pieces of apparatus labelled:

A.........................................................................................................................

B.........................................................................................................................

C.....................................................................................................................[3]

(b) What does the term excess mean?

............................................................................................................................

........................................................................................................................[1]

spatula

beaker

funnel

more than enough





20

(22) Nov 2003 Q (1)

1 The apparatus below was used to separate ethanol from water.

(a) Complete the empty boxes to name the pieces of apparatus. [3](b) Indicate by an arrow where heat is applied. [1](c) Name this separation process.

........................................................................................................................[2]

(23) Nov 2003 Q (2)

2 A student extracted and investigated the orange colour in some sweets.The student followed these instructions:

1 Collect sweets, a watch glass, a beaker, eye protection and 100 cm 3 of ethanol.

2 Crush the sweets.

3 Place the crushed sweets in the beaker containing 100 cm 3 of ethanol.

4 Boil the mixture with the watch glass covering the beaker.

5 Decant the liquid and concentrate it by evaporation until the colour is dark orange.

6 Investigate which colours are present in the orange solution.

(a) Why should the sweets be crushed?

............................................................................................................................

........................................................................................................................[2]

condenser

beaker

fractionating column

fractional distillation

larger surface area





21

(b) Why should the experiment be carried out in a well-ventilated laboratory?

........................................................................................................................[1]

(c) State one safety precaution that the student should have taken, otherthan carrying out

the experiment in a well-ventilated laboratory and using eye protection.

........................................................................................................................[1]

(d) State the purpose of the watch glass.

........................................................................................................................[1]

(e) Explain the term decant .

........................................................................................................................[1]

(f) Describe how the student could carry out instruction 6. You may draw adiagram in the space below to help you answer the question.

............................................................................................................................

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........................................................................................................................[5]

because ethanol is inflammable substance

gloves / goggls

to prevent loss of solvent

liquid pour off

chromatography

1) apply orange concentrate to the paper

2) use water as solvent

3) description of elution

4) results of the experiment





22

(24) Nov 2004 Q (1_a, b)

1 The apparatus below was used to make hydrogen. Dilute hydrochloric acidwas added to zinc

(a) Identify the pieces of apparatus labelled

A, ……………………………………………………………………………………….

B, …………...……………………………………………………………………….[2]

(b) Complete the boxes [1]

hydrochloric acid

zinc

measuring cylinder

flask





23

(25) Nov 2004 Q (7)

7 Forged Banknote A fake banknote can be investigated by dissolving the ink off the paper.You are provided with four different inks from four different criminals. Describe

an experiment to show which one of these inks is the same as the ink fromthe banknote.

You can use a labelled diagram to help you answer the question.

............................................................................................................................

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........................................................................................................................[6]

chromatography

1) apply inks to the chromatogram paper

2) add organic solvent / water

3) rises up paper4) check highest / position of spots

5) compare to find ink from banknote





24

(26) Nov 2005 Q (1_a, c)

1 A student reacted sulfuric acid with copper(II) oxide. The diagram shows the

procedure followed.

(a) Complete the boxes to identify the pieces of apparatus labelled. [3]

(c) Describe how crystals could be quickly obtained from the solution.

............................................................................................................................

........................................................................................................................[2]

(27) Nov 2005 Q (3_a, c)

3 The green pigment chlorophyll can be obtained from grass.

Step 1 The grass is crushed with sand.

Step 2 The grass is ground with ethanol until the solution is saturated.

Step 3 The solution is separated from the rest of the mixture.

Step 4 The colours in the solution are separated.

(a) What apparatus is used in Step 1?

........................................................................................................................[2]

(b) Suggest why the grass is ground with ethanol rather than water in Step 2.

........................................................................................................................[1]

(c) Name the separation method in Step 3.

........................................................................................................................[1]

spatula

beaker

measuring cylinder

heat to crystallizing point

mortar and pastle

chlorophyll is more soluble in ethanol

filteration





25

(d) Describe how Step 4 is carried out.

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........................................................................................................................[4]

(28) Nov 2006 Q (1_a)

1 The diagram shows the formation of a solution of magnesium hydroxidefrom magnesium.

a) Complete the empty boxes to name the pieces of apparatus. [3]

chromatography

1) add pigments to chromatogram paper2) use water as solvent

tong

watch glass

beaker





26

(29) Nov 2006 Q (6)

6 You are provided with a pot of paint as shown below

The paint is a mixture of a liquid and a solid.The liquid can be dissolved in water. The solids are insoluble in water butsoluble in organic solvents.(a) How can a sample of the solid be separated from the rest of the paint?

............................................................................................................................

............................................................................................................................

........................................................................................................................[2]

(b) How would you determine the number of coloured substances contained inthe solid you separated in (a)?

............................................................................................................................

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........................................................................................................................[4]

(c) The label on the paint tin states

“Touch- dry in three hours”

(i) How could you check this value?

............................................................................................................................

........................................................................................................................[2]

(ii) Suggest how you could speed up this drying process.

........................................................................................................................[1]

1) plant sample + water

2) filteration

3) remove the residue

1) solid + organic solvent2) add to chromatogram paper

3) use solvent

4) description of spots

apply points, start the time

hair dryer / wind / increase temperature





27

(30) Nov 2008 Q (1)

1 The colours present in some blackcurrant sweets can be separated bychromatography.The colours are water-soluble dyes.

The diagrams show how the colours can be extracted from the sweets

(a) Complete the empty boxes to name the pieces of apparatus. [3]

The apparatus below was used to carry out the chromatography.

(b) (i) Name the solvent used.

........................................................................................................................[1]

(ii) Label, with an arrow, the origin on the diagram. [1]

(c) Sketch, in the box, the chromatogram you would expect if two differentcolours were present in the sweets.

stirrer

funnel

mortar

water

-----------------o

o

o





28

(31) Nov 2009 Q (3_b)

3 Three unlabelled bottles of chemicals each contained one of the followingliquids:

• sodium nitrate dissolved in water;

• pure water;

• hexene.

(b) Give a test by which you could identify pure water.Test …………………………………………………………………………………………….

Result ……………………………………………………………………………………… [2]

(32) Nov 2009 Q (7)

7 Leaves from trees contain a mixture of coloured pigments which are not

soluble in water. A student was given these two instructions to investigate thepigments in the leaves.

1. Crush some leaves to extract the coloured pigments.

2. Use the liquid extract to find the number of coloured pigments in the leaves.

(a) What would the student need in order to effectively carry out instruction 1?

............................................................................................................................

............................................................................................................................

............................................................................................................................

........................................................................................................................[3]

(b) Describe an experiment to carry out instruction 2.

A space has been left below if you want to draw a diagram to help answer the

question

............................................................................................................................

............................................................................................................................

............................................................................................................................

............................................................................................................................

........................................................................................................................[4]

boiling point

100 C

pestle

mortar

solvent

sand

chromatography

1) applay spot to chromatogram paper

2) use suitable solvent





29

(33) Nov 2010 [62] Q (1_a)

1) The diagram shows the apparatus used by a student to find theconcentration of hydrochloric acid.Sodium hydroxide solution was added to hydrochloric acid until the solution

was neutral.

(a) Complete the boxes to name the apparatus used. [3]

(34) Nov 2011 [61] Q (3_a)

3 The diagram shows the results of an experiment to separate and identify thecolours present in two coloured mixtures, A and B.Substances C, D, E and F are single colours.

(a) Name this method of separation.

.................................................................................................................................. [1]

burette

pipette

flask

chromatography

..................................................................................... __ solvent





30

(b) Draw a line on the diagram to show the level of the solvent at the beginning of the experiment. [1](c) Why should a pencil be used instead of a pen to draw the origin line?

.......................................................................................................................................

.................................................................................................................................. [1](d) State one difference and one similarity between the coloured mixtures, A and B.

difference .......................................................................................................................

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similarity ........................................................................................................................

.................................................................................................................................. [2]

(e) Which substances are present in mixture A?

.................................................................................................................................. [1]

(35) Nov 2011 [63] Q (1)1 Three sets of apparatus, A, B and C, are shown below.

(a) Complete the empty boxes to name the pieces of apparatus. [3](b) What name is given to the separation method in A?

.................................................................................................................................. [1]

because it is insoluble in water

A has 3 colours while B has 2 colours

both contain same colour

stirrer

funnel

evapourating dish

filteration




(c) Which apparatus would be most suitable to obtain crystals from an aqueoussolution of copper sulfate?

.................................................................................................................................. [1]

(36) Nov 2011 [63] Q (6)

6 The label on an aerosol can of Kleen Air air freshener is shown.

(a) What is meant by the term solvent ?

.................................................................................................................................. [1]

(b) What does the hazard sign indicate?

.................................................................................................................................. [1]

(c) What method could be used to obtain ethanol (boiling point 78 °C) from a mixtureof ethanol and propanone (boiling point 56 °C)?

.................................................................................................................................. [1]

(d) Describe an experiment to investigate the number of coloured substancespresent in a sample of the lemon oil obtained from Kleen Air.

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C

liquid that dissolve other substances

flammable

fractional distillation

chromatography

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Topic 1 answers