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Classified Chemistry IGCSE Paper_3_Topic 13

13Non-metals Mostafa Barakat (0100 165 44 62)

227

Topic 13

Hydrogen

Nitrogen

Ammonia and fertilizers

Sulfur and sulfur dioxide

Making of sulfuric acid

Caron cycle

Green house and global worming

Carbonates

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1) Nov 2001 Q (5_a)

a) In the USA, sulfur is obtained from underground deposits. It burns to formsulfur dioxide. This is used in paper making, to preserve food and in themanufacture of sulfuric acid

(i) Why is sulfur dioxide needed in paper making?

[1]

(ii) How does sulfur dioxide preserve food?

[1]

2) June 2002 Q (2_a)

a) Fermentation of sugars is one method of making ethanol. Vines produceglucose by photosynthesis. The glucose collects in the grapes which grow inclusters on the vine.

a) Vines are attacked by a fungus that ruins the grapes. In 1882 it wasdiscovered that spraying the vines with Bordeaux mixture killed the fungusThe fungicide, Bordeaux mixture, contains water, calcium hydroxide andcopper (II) sulphate.

(i) Name the raw material from which calcium hydroxide is made.

[1]

to bleach it

kills bacteria

calcium oxide

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3) Nov 2002 Q (1_a)

a) Sulfuric acid is made by the Contact Process.

2( ) 2( ) 3( )2 2

g g gSO O SO the forward reaction is exothermic

(i) What are the reaction conditions for the Contact Process?

[3]

(ii) Would the yield of sulphur trioxide increase, decrease or stay the samewhen the temperature is increased? Explain your answer.

[2]

(iii) Describe how sulfur trioxide is changed into concentrated sulfuric acid.

[2]

4) Nov 2003 Q (1_a, b)

1) Ammonia contains the elements nitrogen and hydrogen. It is manufacturedfrom these elements in the Haber process.

2( ) 2( ) 3( )3 2g g gN H NH

The forward reaction is exothermic.

a)(i) Nitrogen is obtained from liquid air by fractional distillation. Why does thistechnique separate liquid oxygen and nitrogen?

Name two raw materials from which hydrogen is manufactured

[3]b) The table shows how the percentage of ammonia in the equilibrium mixturevaries with pressure at 600 C.

(i) Explain why the percentage of ammonia increases as the pressureincreases

[2]

1) temperature = 300 C 2) pressure from 2 to 10 atmp

3) catalyst vanadium(V) oxide

decrease because increase in temperature favours the backward reaction

dissolve sulfur trioxide in concentrated sulfuric acid then add water

because they differ in boiling point

methane and water

because increase in pressure moves the reaction to the right because it is

side of lower moles

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(ii) How would the percentage of ammonia change if the measurements hadbeen made at a lower temperature?Explain your answer

[2]

(iii) State two of the reaction conditions used in the Haber process.

[2]

5) Nov 2003 Q (5_a, b)

5) Sulphur dioxide, SO2, and sulphur trioxide, SO3, are the two oxides ofsulphur.

a) Sulphur dioxide can kill bacteria and has bleaching properties. Give a useof sulphur dioxide that depends on each of these properties

(i) ability to kill bacteria . [1]

(ii) bleaching properties . [1]

b) Sulphur trioxide can be made from sulphur dioxide.

(i) Why is this reaction important industrially?

[2]

(ii) Complete the word equation.

sulphur dioxide + . sulphur trioxide [1]

(iii) What are the conditions for this reaction?

[2]

the percentage of ammonia would increase because the forward reaction is exothermic.

An increase in temperature moves position of equilibrium to the right, that ismore ammonia

1) temperature = 300 to 600 C 2) catalyst = iron 3) pressure = 200 atmp

preserve food

making papers

to make sulfuric acid

oxygen

1) vanadium(V) oxide as oxide 2) temperature = 450 C

3) pressure = 2 atmp

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6) June 2004 Q (2_a, b)

a) Sulphur is used to make sulfuric acid. In the UK, the annual production ofthe acid is about 2.5 million tonnes

(i) Give a large scale source of the element sulphur

[1]

(ii) State another use of sulphur dioxide.

[1]

(iii) How is sulphur changed into sulphur dioxide?

[1]

(iv) Name the catalyst used in reaction 2

[1]

(v) Reaction 2 is exothermic. Why is a catalyst, rather than a highertemperature, used to increase the rate of this reversible reaction?

[2]

(vi) Write a word equation for reaction 3.

[1]

(vii) Write a symbol equation for reaction 4.

[1]

USA or Texas or Poland or Mexico

Preserving food or bleaching wood

burnt in oxygen or air

vanadium(V) oxide

because Increase temperature increases rate but reduces yield catalyst only

increases rate or a catalyst does not influence position of equilibrium

sulphur trioxide + sulphuric acid oleum

H2S2O7 + H2O 2H2SO4

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b) About one third of this production of acid is used to make nitrogen andphosphorus containing fertilizers.

(i) Name the third element that is essential for plant growth and is present inmost fertilisers.

[1]

(ii) Name a nitrogen-containing fertilizer that is manufactured from sulphuricacid.

[1]

7) June 2005 Q (4_c)

c) Sulfuric acid is manufactured by the Contact Process. Sulphur dioxide is

oxidized to sulphur trioxide by oxygen.

2 2 32 2SO O SO

(i) Name the catalyst used in this reaction

[1]

(ii) What temperature is used for this reaction?

[1]

(iii) Describe how sulphur trioxide is changed into sulfuric acid.

[2]

8) Nov 2005 Q (7_a, b)

In 1909, Haber discovered that nitrogen and hydrogen would react to formammonia. The yield of ammonia was 8%.

a) Describe how hydrogen is obtained for the modern process.

[2]

b)(i) What is the catalyst in the modern process?

[1]

potassium

ammonium sulphate

vanadium(V) oxide

450 C

add to sulfur trioxide to concentrated sulphuric acid then add water

from methane and water

iron

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(ii) Explain why the modern process, which uses a lower temperature, has ahigher yield of 15%.

[2]

9) June 2006 Q (5_a)

a) Sulfuric acid is made by the Contact process in the following sequence ofreactions

(i) How is sulphur dioxide made from sulphur?

[1]

(ii) Sulphur dioxide has other uses. Why is it used in the manufacture ofpaper?

[1]

(iii) How does it preserve food?

[1]

b) The equation for a stage of the Contact process is

2 2 32 2SO O SO

The percentage of sulphur trioxide in the equilibrium mixture varies withtemperature

(i) How does the percentage of sulphur trioxide in the equilibrium mixture varyas the temperature increases? Circle the correct answer.

Increase Stay the same Decrease [1]

lower temperature moves equilibrium to right because forward reaction

is exothermic

by Burn sulphur in air

to bleach it

it kill bacteria

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(ii) Is the forward reaction in the equilibrium 2SO2 + O2 2SO3

exothermic or endothermic? Give a reason for your choice.

[2]

(iii) Explain, mentioning both rate and percentage yield, why the temperatureused in the Contact process is 450 C.

[2]

(iv) Describe how the sulphur trioxide is changed into concentrated sulfuricacid.

[2]

10) Nov 2006 Q (5_a, b)

Ammonia is manufactured by the Haber process.

The forward reaction is exothermic

a)

(i) What is the catalyst for this reaction?

[1]

(ii) Newer catalysts have been discovered for this process. Using these

catalysts, the operating temperature is lowered from 450 C to 400 C. Whatis the advantage of using a lower temperature?

Explain your answer

Advantage .

Explanation .....

[2]

b) After passing over the catalyst, the mixture contains 15% of ammonia. It iscooled and the ammonia liquefies and is separated from the unreactednitrogen and hydrogen. They are recycled.

(i) How are the gases recycled?

[1]

exothermic because increase temperature favours back reaction so it is

endothermic, so forward reaction must be exothermic

Low enough for good yield

High enough for (economic) rate

bubble sulfur trioxide into concentrated sulfuric acid then add water

iron

higher yield

lower temperature favours the exothermic reaction that is the

forward reaction

Sent over the catalyst again to make more ammonia

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(ii) Only ammonia gas liquefies. Suggest an explanation for this.

[1]

11) Nov 2007 Q (4_a)

a) Zinc blende is heated in air to give zinc oxide and sulphur dioxide. Most ofthe sulphur dioxide is used to make sulphur trioxide. This is used tomanufacture sulphuric acid. Some of the acid is used in the plant, but most ofit is used to make fertilisers.

(i) Give another use of sulphur dioxide.

[1]

(ii) Describe how sulphur dioxide is converted into sulphur trioxide

[3]

(iii) Name a fertiliser made from sulphuric acid.

[1]

12) June 2009 Q (6_a)

6 Ammonia is manufactured by the Haber process

N2(g) + 3H2(g) 2NH3(g) the forward reaction is exothermic

a)(i) Name the raw materials from which nitrogen and hydrogen are obtained

Nitrogen from .[1]

Hydrogen from .[1]

(ii) Name the catalyst used in this process.

[1]

(iii) What is the most important use of ammonia?

[1]

because It has the highest boiling point

bleach wood

react with oxygen at 450C and in the presence of vanadium(V) oxide as catalyst

and 2 atmospheric pressure

ammonium sulfate

air

water

iron

making fertilizers

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13) Nov 2009 Q (6_a)

a) Sulfuric acid is made by the contact process

2 2 32 2SO O SO

This is carried out in the presence of a catalyst at 450 C and 2 atmosphericpressure

(i) How is the sulfur dioxide made?

[1]

(ii) give another use of sulfur dioxide

[1]

(iii) name the catalyst used

[1]

(iv) if the temperature is decreased to 300 C, the yield of sulfur trioxideincreases. Explain why this lower temperature is not used

[1]

(v) sulfur trioxide is dissolved in concentrated sulfuric acid. This added towater make more sulfuric acid. Why is sulfur trioxide not added directly towater?

[1]

14) June 2010 [31] Q (1_iv)

1 Choose an element which fits each of the following descriptions.

(iv) It has a basic oxide of the type MO which is used to treat acidic soils.

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

15) June 2010 [31] Q (8_b, i)

(b) In some areas when water is boiled, the inside of kettles becomes coatedwith a layer of calcium carbonate. This can be removed by adding methanoicacid.

(i) Complete the equation.

3 2....... ( ) .......... ...........HCOOH CaCO Ca HCOO

[2]

by burn sulfur in air

bleach for wood pulp

vanadium(V) oxide

because rate too slow and not economic

because reaction too violent

calcium

2 CO H O22

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16) Nov 2010 [31] Q (7)

7 The diagram shows part of the carbon cycle. This includes some of theprocesses which determine the percentage of carbon dioxide in theatmosphere.

(i) Carbon dioxide is one greenhouse gas. Name another one........................................................................................................................ [1]

(ii) Explain the term respiration and how this process increases thepercentage of carbon dioxide in the atmosphere.

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

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

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

(iii) Explain why the combustion of waste crop material should not alter thepercentage of carbon dioxide in the atmosphere.

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

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

(iv) In 1960 the percentage of carbon dioxide in the atmosphere was 0.032%and in 2008 it was 0.038%. Suggest an explanation for this increase.

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

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

17) Nov 2010 [32] Q (7_a, b)7 The major use of sulfur dioxide is to manufacture sulfuric acid.

(a) (i)Another use of sulfur dioxide is as the food additive E220.

How does it preserve food?

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

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

(ii) Why is sulfur dioxide used in the manufacture of wood pulp?

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

methane

living organisms produce energy from food

this forms carbon dioxide which leads to increase the percentage of carbon

dioxide in air

when growing the crop removed carbon dioxide from atmosphere

while combustion returned the carbon dioxide

due to the increased combustion of fossil fuels

it kill bacteria

to bleach it

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(iii) How is sulfur dioxide manufactured?

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

(b) Complete the following description of the manufacture of sulfuric acid.

Sulfur dioxide reacts with .................................. to form sulfur trioxide.The above reaction is catalysed by ................................................. .

The optimum temperature for this reaction is .............................. C.

Sulfur trioxide needs to react with ............................... to form sulfuric acid. [4]

18) Nov 2011 [32] Q (2)

2 Sulfur is needed for the production of sulfuric acid. Two of the major sourcesof sulfur are

underground deposits of the element sulfur,

sulfur compounds from natural gas and petroleum.

(a) Explain why sulfur and its compounds are removed from these fuelsbefore they are burned.

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

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

(b) Sulfur dioxide is made by spraying molten sulfur into air. The sulfur ignitesand sulfur dioxide is formed.

(i) Suggest why molten sulfur is used in the form of a fine spray.

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

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

(ii) Explain why traces of sulfur dioxide act as a preservative in fruit juices.

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

(iii) State another use of sulfur dioxide.

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

(c) Describe how sulfur dioxide is changed into sulfur trioxide. Give thereaction conditions and an equation.

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

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

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

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

(d) Complete the following equations for the formation of sulfuric acid fromsulfur trioxide.

3 2 2 7...............SO H S O

2 2 7 2 4

............ ..........H S O H SO [2]

by burn sulfur in air

oxygen

vanadium(V) oxide

450

water

because it burns to form sulfur dioxide which dissolve in water vapour

which causes acid rain

because it has bigger surface area which reacts faster

because it kills microbes

bleach wood

heat sulfur dioxide in air 2 SO + O SO2 2 3conditions 1) temperature = 450 C

2) catalyst = vanadium(V) oxide

3) pressure = 2 atmp

H SO2 4

H O2 2

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19) Nov 2011 [3 ] Q (3)

3 Fertilisers are used to promote plant growth.

Two fertilisers are ammonium phosphate, (NH4)3PO4, and calcium dihydrogenphosphate, Ca(H2PO4)2.

(a) Describe a test to distinguish between these two fertilisers.

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

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

result ..............................................................................................................................

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

(b) Many fertilisers are manufactured from ammonia. Describe how ammoniais made in the Haber process. Give the essential conditions and an equationfor the process.

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

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

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

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

(c) State the essential plant nutrient not supplied by ammonium phosphate.

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

(d) The soluble compound, calcium dihydrogenphosphate is made by heatingthe insoluble mineral rock phosphate, Ca3(PO4)2, with sulfuric acid.

(i) Why would rock phosphate not be effective as a fertiliser?

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

20) Nov 2011 [32] Q (3)

3 Fertilisers are used to promote plant growth.

Two fertilisers are ammonium phosphate, (NH4)3PO4, and calcium dihydrogenphosphate, Ca(H2PO4)2.

(a) Describe a test to distinguish between these two fertilisers.

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

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

result ..............................................................................................................................

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

(b) Many fertilisers are manufactured from ammonia. Describe how ammoniais made in the Haber process. Give the essential conditions and an equationfor the process.

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

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

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

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

3

add sodium hydroxide solution then warm

only ammonium phosphate gives off ammonia gas which will turn red

litmus paper blue

1) temperature = 450 C

2) pressure = 200 atmospheres

3) catalyst = iron

by direct combination between nitrogen and hydrogen (N + 3 H NH )2 2 3

potassium

because it needs to be soluble

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(c) State the essential plant nutrient not supplied by ammonium phosphate.

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

(d) The soluble compound, calcium dihydrogenphosphate is made by heatingthe insoluble mineral rock phosphate, Ca3(PO4)2, with sulfuric acid.

(i) Why would rock phosphate not be effective as a fertiliser?

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

21) Nov 2012 [32] Q (5)

5 The food additive E220 is sulfur dioxide. It is a preservative for a variety offoods and drinks.

(a) State two other uses of sulfur dioxide.

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

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

(b) How is sulfur dioxide manufactured?

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

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

(c) Sulfur dioxide is a reductant (reducing agent). Describe what you wouldsee when aqueous sulfur dioxide is added to acidified potassiummanganate(VII).

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

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

22) Nov 2012 [33] Q (7_a, b)

7Ammonia is made by the Haber process.

2( ) 2( ) 3( )3 2

g g gN H NH

(a) State one major use of ammonia.

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

(b) Describe how hydrogen is obtained for the Haber process.

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

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

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

(c) This reaction is carried out at a high pressure, 200 atmospheres.

State, with an explanation for each, two advantages of using a high pressure.

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

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

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

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

bleaching wood pulp

manufacture of sulfuric acid

by heating sulfur in air

the colour changed from purple to colourless

making fertilizers

by electrolysis of acidified water. Hydrogen gas formed at cathode

2) more collisions so the collisions are more frequent

3) higher yield because high pressure favours the reaction with less moles

4) high pressure means lower temperature can be used to achieve comparable rate(thus saving energy);

1) increase pressure increase the rate of the reaction

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(b) Ammonia is manufactured by the Haber process. The economics of thisprocess require that as much ammonia as possible is made as quickly aspossible.

Explain how this can be done using the following information.

The conditions for the following reversible reaction are:

450 C

200 atmospheres pressure

iron catalyst

2( ) 2( ) 3( )3 2 the reaction is exothermicg g gN H NH

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

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

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

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

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

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

3 The diagram shows some of the processes which determine the percentageof carbon dioxide in the atmosphere.

(a) Explain how the following two processes alter the percentage of carbon

dioxide in the atmosphere.

(i) combustion

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

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

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

(ii) respiration

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

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

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

24) June 2013 [32] Q (3)

23) June 2013 [32] Q (6_b)

1) high pressure favours lower volume side

2) high pressure increases rate

3) catalyst increases rate or lowers activation energy

4) low temperature favours exothermic reaction which increases yield

5) low temperature gives low rate

complete combustion of fuels containing carbon produce carbon dioxide

which increase percentage of CO2 in atmosphere

living things (cells / plants / animals / humans) oxidise carbohydrate

produces carbon dioxide

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(b) Photosynthesis reduces the percentage of carbon dioxide in theatmosphere.

(i) Complete the word equation for photosynthesis.

carbon dioxide + water ........................ + ........................

[2]

(ii) State two essential conditions for the above reaction to occur.

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

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

glucose oxygen

1) light

2) chlorophyll

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13 Non Metals