alternative to practical questions igcseset 1

8/13/2019 Alternative to Practical Questions IGCSEset 1

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IGCSE Chemistry CIE Paper 6 Set 1(Alternative to practical)

Question 1

Solutions A and B are colourless. hen they are mi!ed" they react and turn #lue a$ter aperiod o$ time. A student investi%ated ho& temperature a$$ected the rate o$ reaction

#et&een solutions A and B. 'he rate &as measured #y time taen $or the solution to turn#lue &hen they are mi!ed.'he results are sho&n in the ta#le.

(a) (i) ra& a %raph $or these results.

Compiled by Mr Chris D Chemistry Tutor 019-38689501


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(ii) *se your %raph to $ind ho& lon% it taes the solution to turn #lue at +, -C.

'ime ......................................... s (2 mark)



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(#) (i) /o& does the rate o$ reaction chan%e as the temperature is increased0

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(1 mark)(ii) E!plain" in terms o$ particles" &hy temperature has this e$$ect on the rate o$ reaction.To gain full marks in this question you should write your ideas in good English. Puttheminto a sensible order and use the correct scientific words.

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(c) State one varia#le that must #e ept constant to mae this e!periment a $air test.

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.(1 mark)

(d) easurin% cylinders &as used to measure the t&o solutions. Give one advanta%eand disadvanta%e o$ usin% a measurin% cylinder.

Advanta%e2

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isadvanta%e2

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(2 mark)

Question 3A student conducted an e!periment to determine the value o$ ! in hydrated copper(II)sul$ate crystals" CuS4+.x/34.

A sample o$ hydrated copper(II) sul$ate crystals" CuS4+.x/34 &as &ei%hed in a cleanand dry test tu#e.

'he crystals &ere %ently heated until they #ecame anhydrous" i.e. no more &ater vapour&as %iven o$$.It &as o#served that the crystals chan%ed colour and #ecame po&dery.ata collected &as as $ollo&s2

ass o$ empty test5tu#e .+, %

ass o$ test5tu#e 7 hydrated copper(II) sul$ate crystals 8.3 %

ass o$ test5tu#e 7 copper(II) sul$ate a$ter heatin% 9.8, %

(a) hat colour are hydrated copper(II) sul$ate crystals0

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(b) Calculate the mass o$ hydrated copper(II) sul$ate used in the e!periment.

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(c) (i) hat colour &as the copper(II) sul$ate a$ter heatin%0

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(ii) Give a test to prove that &ater &as released $rom the heatin%.

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(d) (i) Calculate the anhydrous mass o$ copper(II) sul$ate &hich remained a$ter heatin%.



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(ii) Calculate the mass o$ &ater lost $rom the crystals.

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(e) From the data collected and using the relative atomic mass of elements in theperiodic table, calculate the $ollo&in%2(i) the moles o$ anhydrous copper(II) sul$ate &hich remained a$ter heatin%.

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(ii) the moles o$ &ater lost $rom the crystals that &as heated in the e!periment.

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(f) Then determine the value o$ !.

:3;



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Question , -C) and methyl#en=ene (#.p. 111 -C) #y usin% theapparatus sho&n #elo&.

(a) ?ame the method used #y the student #ased on the apparatus used a#ove and %ivea reason &hy this &ould #e the #est method in separatin% #en=ene and methyl #en=ene.

?ame o$ method2@@@@@@@@@@@@@@@@@@@@@@@@@@@@@.

eason2 @@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@

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(#) Identi$y one error done #y the student #ased on the dia%ram %iven a#ove.

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(c) ?ame the part la#elled A.

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(d) ?ame the apparatus Band e!plain the role o$ apparatus B in the e!periment a#ove.

?ame2 ........................................................................................................................

ole o$ B2 @@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@

@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@..:3;(d) E!plain #rie$ly &hy an electric heater rather than a $lame $rom Bunsen #urner inheatin% the mi!ture0

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(e) In the e!periment pure liuid o$ one su#stance &as produced.hat &as the readin% on the thermometer &hen the $irst $e& drops o$ distillateappeared in C. 'hen identi$y &hich su#stance &as produced.

'hermometer readin%2 @@@@@@@@@@@@@@@@@@@@@@@@@@

Identity o$ the pure liuid $ormed2 @@@@@@@@@@@@@@@@@@@@@.

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($) 'he pure liuid produced in apparatus C is volatile and can easily evaporate. 'hevolume o$ liuid produce &as measured #y usin% a measurin% cylinder.

(i) hat modi$ication &ould you do to prevent the liuid $rom evaporatin% o$$ $romapparatus C.

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(ii) Give a disadvanta%e and a disadvanta%e o$ measurin% the volume o$ the pure liuidcollected $rom this e!periment.

Advanta%e2@@@@@@@@@@@@@@@@@@@@@@@@@@@@@.

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isadvanta%e2@@@@@@@@@@@@@@@@@@@@@@@@@@@@.

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Question +Iron wire actually contains iron mixed with copper metal. To determine the percentage of

iron in the iron wire, a student dissolved the iron from the iron wire in sulfuric acid.

Copper will not dissolved in dilute sulphuric acid. A student determined the percentage

of iron in the iron wire by titration with 0.020 mol/dm3

potassium manganate(VII), KMnO4,in a burrete. The solution of potassium

manganate(VII)which is purple.

(a) A piece of iron wire was added to a previously weighed container which was then

reweighed.

Mass of container + iron wire = 7.39 g

Mass of container = 5.74 g

Calculate the mass of iron wire used in the experiment.

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

The iron wire was placed in a conical flask as shown below. Sufficient dilute sulfuric acid

was added to react completely with the iron wire. Bubbles of colorless gas was

observed. The flask was warmed to convert the iron into iron(II) ions, Fe2+. Equal

amount of sulfuric acid was added added to ensure all iron dissolves in the solution. The

valve allows the gas to escape but does not allow air into the flask.

(b)



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(b (i) Using your knowledge of Redox chemistry, explain why was it

necessary to prevent air entering the apparatus.

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.(ii) Deduce the identity of the gas produced in the reaction.

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(iii) Describe the test to deduce the identity of the gas. Give the correct

observation.

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!"

When all the iron had reacted, the solution was cooled and made up to 250 cm3 with

dilute sulphuric acid in a graduated flask. This was solution P.



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A 25.0 cm3sample of this solution P was transferred from a pipette into a titration flask

and titrated with 0.020 moldm-3potassium manganate(VII) from the burette until

endpoint.

Two titrations were done. Parts of the burette with the liquid levels before and after each

titration are shown below:

(c) Use the diagrams to complete the results table.

Calculate the average volume of potassium manganate(VII) that was required to react

with 25.0 cm3solution P.

(d) What colour change showed that the end point had been reached?

The colour changed from ....................................... to .................................................[1]

(e) Calculate how many moles were present in the average volume of 0.020 moldm-3

KMnO4solution.

...................................mol KMnO4 [1]



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(f) #rom a $alanced e%uation, &moles of Fe 2+reacted completely with 1 mole of

KMnO4.

Calculate how many moles of Fe 2+were present in 25.0 cm3of solution P.

...................................mol Fe 2+ [1]

(g) Calculate how many moles of Fe 2+were in 250 cm3of solution P.

...................................mol Fe 2+ [1]

(h) ' mole of #e forms ' mole of Fe 2+, calculate the mass of iron in 250 cm3of the

solution P.

................................... gram of iron that dissolved in 250 cm3of the solution P [1]

(i) Using your answers to (a) and (h), calculate then the percentage of iron in the iron

wire.

% iron in the wire =....................... [1]

Question 5

The following table shows the tests on substance W and the conclusions made from the

observations.

Complete the table by describing these observations and suggest the test and

observations which led to the conclusion from test 4.



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Conclusion

W is zinc chloride.

Question 6

A student did four experiments to find how the solubility of sodium nitrate varies with

temperature.



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A 20.0 g sample of sodium nitrate was put into the beaker and 10.0 cm3 of water were

added. The beaker was heated and the contents stirred until all the solid was dissolved.

The beaker was allowed to cool slowly. The temperature at which crystals first appeared

was noted. A further 10.0 cm3 of water were added and the process repeated. The

experiment was repeated for two further 10.0 cm3 additions of water.

(a) The diagrams below show the thermometer when crystals appeared fortotal volumes of 10.0, 20.0, 30.0 and 40.0 cm3.

The solubility of sodium nitrate at each temperature was calculated by using the formula

below.

(i) Complete the temperature column using the temperatures shown in the diagram.

(ii) Complete the solubility column using the formula shown above.

(b)Plot the results on the grid below. Connect the points with a smooth curve and

extend this curve to meet the vertical axis.



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Use the curve to answer the following questions.



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(c) What is the solubility of sodium nitrate at

(i) 10 C,

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(ii) 70 C?

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[2]

(d) What is the lowest temperature at which 100 cm3of water will dissolve 110 g of

sodium nitrate?

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(e) A hot solution of 150 g of sodium nitrate in 100 cm3of water was cooled to 50 C.

What mass of sodium nitrate crystallised out?

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Good Luck.


alternative to practical questions igcseset 1

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