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Topic 4: Organic Chemistry
Subtopic 4a, b, c, d: Introduction, Crude oil, Alkanes, Alkenes
1) Crude oil is a mixture of hydrocarbons.
(a) This passage is about the industrial separation of crude oil.
Complete the passage by adding the missing words. (3)
Crude oil is ............................................................................................. to form vapour.
The vapour is passed through a ............................................................................................. column.
The refinery gases are collected at the top of the column because they have low ................................................ ................................................
(b) Bitumen is collected at the bottom of the column. Give one use of bitumen. (1) .............................................................................................................................................
(c) One of the hydrocarbons in crude oil is an alkane with this structural formula. CH3CH2CH2CH2CH3
(i) Give the name of this alkane. (1)
.............................................................................................................................................
(ii) Calculate the relative molecular mass (Mr) of this alkane. (1)
Mr = ...........................................................
(d) Catalytic cracking is used to convert long-chain alkanes into shorter-chain alkanes.
Give the name of the catalyst and the temperature used in catalytic cracking. (2)
catalyst .............................................................................................................................................
temperature .............................................................................................................................................
(e) Catalytic cracking also produces alkenes.
Decane (C10H22) can undergo cracking to give C4H10 and two different alkenes.
Complete the equation for this cracking process. (2)
C10H22 → C4H10 + .............................................................. + ..............................................................
2) Crude oil is a mixture of hydrocarbons.
(a) Name the process used to separate crude oil into fractions. (1) .............................................................................................................................................
(b) Give one use of the kerosene fraction. (1) .............................................................................................................................................
(c) One of the hydrocarbons in the refinery gas fraction is an alkane with the structural formula CH3CH2CH2CH3
(i) Give the name of this alkane. (1)
.............................................................................................................................................
(ii) Calculate the relative molecular mass (Mr) of this alkane. (1)
Mr ...........................................................
(d) One of the alkanes in the gasoline fraction has the displayed formula
(i) Determine the molecular formula of this alkane. (1) .............................................................................................................................................
(ii) Give the general formula for the alkanes. (1) .............................................................................................................................................
(e) Catalytic cracking is used to convert long-chain alkanes into shorter-chain alkanes.
(i) Name the catalyst used in catalytic cracking. (1) .............................................................................................................................................
(ii) Explain why it is necessary to convert long-chain alkanes into shorter-chain alkanes. (2) ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. .............................................................................................................................................
(f) Catalytic cracking also produces alkenes.
C11H24 can undergo cracking to give pentane (C5H12) and two different alkenes.
Complete the equation for this cracking reaction. (2)
(Total for question = 11 marks)
3) Crude oil is a mixture of hydrocarbons, most of which are alkanes. (a) (i) State what is meant by the term hydrocarbon. (2)
............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. .............................................................................................................................................
(ii) Give the general formula for the alkanes. (1)
.............................................................................................................................................
(b) Name the process used to separate crude oil into fractions. (1) .............................................................................................................................................
(c) One of the fractions obtained from crude oil is fuel oil. Fuel oil is used to heat homes.
Explain why burning fuel oil in an insufficient supply of oxygen is dangerous. (2) ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. .............................................................................................................................................
(d) Another fraction obtained from crude oil is gasoline.
Gasoline is used to make petrol for cars.
(i) Explain why it is dangerous to light a match even when standing several metres away from a petrol spillage. (2) ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. .............................................................................................................................................
(ii) Suggest why a petrol spillage is more dangerous than a fuel oil spillage. (1) ............................................................................................................................................. .............................................................................................................................................
(Total for question = 9 marks)
4) The diagram shows the industrial equipment used to separate crude oil into fractions.
(a) (i) Give the name of the industrial equipment. (1) .............................................................................................................................................
(ii) Give one use of the fuel oil fraction. (1) .............................................................................................................................................
(iii) Give the names of fraction A and fraction F. (2)
fraction A .............................................................................................................................................
fraction F .............................................................................................................................................
(b) One compound in the gasoline fraction is the alkane octane (C8H18) and one compound in the kerosene fraction is the alkane dodecane (C12H26)
These two alkanes are covalently bonded and have simple molecular structures.
(i) Give the general formula for the alkanes. (1) .............................................................................................................................................
(ii) Explain, in terms of their structures, why C12H26 has a higher boiling point than C8H18 (3) ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. .............................................................................................................................................
(c) Catalytic cracking can be used to convert the alkane C12H26 into more useful products.
(i) Give the name of the catalyst used for catalytic cracking. (1) .............................................................................................................................................
(ii) Complete the equation for this cracking reaction. (1)
C12H26 → C9H20 + ..................................................
(Total for question = 10 marks)
5) The flow chart shows how ethene can be obtained industrially from crude oil
(a) Step 1 involves the use of a tall column.
Describe how the diesel fraction is obtained from the crude oil in step 1. (5) ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. .............................................................................................................................................
(b) In step 2, saturated compounds such as dodecane are obtained from the mixture of hydrocarbons in the diesel fraction.
Explain why dodecane is described as a saturated hydrocarbon. (3) ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. .............................................................................................................................................
(c) Which of these formulae is that of an alkane? (1)
A C7H12
B C9H18
C C11H24
D C13H30
(d) In step 3, cracking is used to convert alkanes into alkenes.
Complete the equation to show the reaction in which one molecule of dodecane is converted into two molecules of ethene and one molecule of another hydrocarbon. (1)
C12H26 → 2C2H4 + ........................................
(e) Alkanes and alkenes both react with halogens, but in different ways.
The equations for two examples of these different reactions are shown.
equation 1
C2H6 + Cl2 → C2H5Cl + compound X
equation 2
C2H4 + Br2 → C2H4Br2 (i)
State the condition needed for the reaction in equation 1 to occur. (1) .............................................................................................................................................
(ii) Deduce the formula of compound X. (1) .............................................................................................................................................
(iii) Draw a dot-and-cross diagram to represent a molecule of C2H5Cl Show only the outer electrons of each atom. (2)
(iv) Equation 2 shows an example of an addition reaction.
State the type of reaction shown by equation 1. (1) .............................................................................................................................................
(f) Alkenes can be distinguished from alkanes using bromine water.
(i) What colour change occurs in the reaction between propene and bromine water? (1)
A colourless to orange
B colourless to green
C green to colourless
D orange to colourless
(Total for question = 13 marks)
6) Carbon monoxide, CO, and oxides of nitrogen are produced in a car engine when petrol is burned.
These oxides can be partly removed by using a catalytic converter fitted to the car's exhaust system.
(i) State how oxides of nitrogen are produced in the car engine. (1) ............................................................................................................................................. .............................................................................................................................................
(ii) Give a disadvantage of allowing oxides of nitrogen to escape into the atmosphere. (1) ............................................................................................................................................. .............................................................................................................................................
(iii) Write a chemical equation for the reaction between nitrogen monoxide, NO, and carbon monoxide to form carbon dioxide and nitrogen. (1)
.............................................................................................................................................
(Total for question = 3 marks)
7) This question is about three stages in the manufacture of sulfuric acid.
(a) In stage 1, sulfur is burned in oxygen to form sulfur dioxide gas.
S(s) + O2(g) → SO2(g)
(i) State one environmental problem caused by the release of sulfur dioxide into the atmosphere. (1) ............................................................................................................................................. .............................................................................................................................................
(Total for question = 11 marks)
8) Propane is a hydrocarbon with the formula C3H8 (a) State why propane is a hydrocarbon. (2) ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. .............................................................................................................................................
(b) (i) Name the poisonous gas that forms when propane is burned in a limited supply of air. (1) ............................................................................................................................................. .............................................................................................................................................
(ii) State why this gas is poisonous to humans. (1) ............................................................................................................................................. .............................................................................................................................................
(d) Propane can be produced by cracking.
An equation for cracking is C13H28 → C3H8 + 2C3H6 + 2C2H4
Explain why cracking is an important process in the oil industry. (3) ............................................................................................................................................. .............................................................................................................................................
(e) Propane reacts with bromine in the presence of ultraviolet radiation.
(i) Complete the equation for this reaction. (2)
C3H8 + Br2 → ........................................................... + ...........................................................
(ii) Give the name of this type of reaction. (1) ............................................................................................................................................. .............................................................................................................................................
(Total for question = 10 marks)
9) Crude oil is a mixture of organic compounds.
Most of these compounds are members of the same homologous series.
(a) State the name of this homologous series. (1) .............................................................................................................................................
(b) An industrial process is used to separate crude oil into fractions.
(i) The process depends on a difference in a property of the fractions. What is this property? (1)
A boiling point
B density
C melting point
D solubility
10) (a) There are three isomers with the molecular formula C5H12 One of these isomers is pentane.
The displayed formula for pentane is
(i) State what is meant by the term isomers. (2) ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. .............................................................................................................................................
(ii) Draw the displayed formula for another isomer of C5H12 (2)
(b) Pentane reacts with bromine in the presence of ultraviolet radiation.
(i) Complete the equation for this reaction.
(ii) Give the name of this type of reaction. (1) .............................................................................................................................................
(Total for question = 7 marks)
11) A sample of a gaseous hydrocarbon, X, has a volume of 600 cm3 at room temperature and pressure (rtp).
(a) Calculate the amount, in moles, of hydrocarbon X in the sample. [molar volume of a gas = 24 000 cm3 at rtp] (2)
amount of hydrocarbon X = ........................................................... mol
(b) The mass of the sample of hydrocarbon X is 1.45 g.
Show that the relative molecular mass (Mr) of X is 58 (2)
Mr = ...........................................................
(c) Hydrocarbon X is an alkane. Show that the molecular formula of X is C4H10 (1)
(d) Give the displayed formula of the branched-chain isomer of hydrocarbon X. (1)
(Total for question = 6 marks)
Subtopic 4e, f, g, h: Alcohols, Carboxylic acids, Esters, Synthetic polymers
1) This question is about the unsaturated hydrocarbon, ethene. The displayed formula of ethene is
(a) (i) State the meaning of the term hydrocarbon. (2) ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. .............................................................................................................................................
(ii) Give the reason why ethene is described as unsaturated. (1) ............................................................................................................................................. .............................................................................................................................................
(b) Ethene is bubbled through bromine water until there is no further colour change.
Which of these is the appearance of the solution formed? (1)
A colourless B orange C purple D red
(c) Ethanol is produced industrially by the reaction between ethene and steam.
The equation for the reaction is CH2CH2(g) + H2O(g) → CH3CH2OH(l)
(i) State the temperature and pressure used in this reaction. (2)
temperature .............................................................................................................................................
pressure .............................................................................................................................................
(ii) Give the molecular formula of ethanol. (1) .............................................................................................................................................
(Total for question = 7 marks)
2) This question is about alcohols, carboxylic acids and esters. (a) The table gives information about some alcohols.
Complete the table by giving the missing information. (2)
(b) Ethanol can be oxidised to ethanoic acid by heating with potassium dichromate(VI) and another reagent.
(i) Name the other reagent. (1)
.............................................................................................................................................
(ii) State the colour change that occurs during this reaction. (1)
from ........................................................... to ......................................................................
(c) Alcohols react with carboxylic acids to form esters.
(i) Name the ester that forms when ethanol reacts with ethanoic acid. (1) .............................................................................................................................................
(ii) Complete the equation for the reaction between methanol and ethanoic acid. (2)
CH3OH + ................................................. → ..................................................+ H2O
(Total for question = 7 marks)
3) Ethanol, C2H5OH, is a member of the homologous series of alcohols.
(a) Give two characteristics of a homologous series. (2)
1 .......................................................................................................................................... .............................................................................................................................................
2 ..........................................................................................................................................
.............................................................................................................................................
(b) When ethanol is heated with potassium dichromate(VI) and one other reagent, the ethanol is oxidised to ethanoic acid, CH3COOH (i) Give the formula of the other reagent. (1) .............................................................................................................................................
(ii) State the colour change that occurs during this oxidation reaction. (2)
from ....................................................................... to .......................................................................
(iii) Draw the displayed formulae for ethanol and ethanoic acid in the boxes. (2)
............................................................................................................................................. ............................................................................................................................................. .............................................................................................................................................
(ii) The word equation for the fermentation process is glucose → ethanol + carbon dioxide
Complete the chemical equation for this reaction. (1)
C6H12O6 → ..................................................................... + .....................................................................
(Total for question = 14 marks)
4) (a) Ethanol, C2H5OH, can be oxidised to produce ethanoic acid, CH3COOH, by heating it with potassium dichromate(VI).
(i) Name one other reactant needed for this reaction to occur. (1) ............................................................................................................................................. \
(ii) Which colour change occurs during this reaction? (1)
A colourless to green
B green to orange
C orange to colourless
D orange to green
(b) Ethanol reacts with methanoic acid, HCOOH, in the presence of an acid catalyst to form an ester.
The equation for the reaction is C2H5OH + HCOOH ⇔ HCOOC2H5 + H2O
(i) Give the name of the ester that forms. (1) .............................................................................................................................................
(ii) Draw the displayed formula for this ester. (2)
(iii) When this reaction takes place in a sealed container, the reaction can reach dynamic equilibrium.
Give two characteristics of a reaction at dynamic equilibrium. (2)
1 .......................................................................................................................................... .............................................................................................................................................
2 .......................................................................................................................................... .............................................................................................................................................
(Total for question = 7 marks)
5) Some cars in Brazil use ethanol, C2H5OH, as a fuel instead of petrol.
The ethanol is made by the fermentation of glucose which is obtained from sugar cane.
The sugar is extracted from the sugar cane and then dissolved in water to make a sugar solution. (a)
(i) Name the substance that is added to the sugar solution that causes glucose to ferment. (1) .............................................................................................................................................
(ii) Which temperature is the most suitable for fermentation? (1)
A 0°C
B 10°C
C 30°C
D 80°C
(iii) Explain why fermentation is done in the absence of air. (2) ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. .............................................................................................................................................
(b) (i) State what is meant by the term fuel. (1) ............................................................................................................................................. .............................................................................................................................................
(ii) Write a chemical equation for the complete combustion of ethanol in air. (2) .............................................................................................................................................
(c) Ethanol is also manufactured by reacting steam with ethene, C2H4
The equation for this reaction is State the conditions of temperature and pressure used in this process. (2)
temperature .............................................................................................................................................
pressure .............................................................................................................................................
(d) When ethanol is heated with acidified potassium dichromate(VI), it is oxidised to ethanoic acid.
(i) State the colour change that occurs in the potassium dichromate(VI) during this reaction. (1)
From .................................................. to ..................................................
(ii) The structural formula of ethanoic acid is CH3COOH
Draw the displayed formula of ethanoic acid. (2)
(iii) Complete the equation for the reaction of ethanoic acid with sodium. (2)
(Total for question = 14 marks)
6) The table shows the structures of six organic compounds.
(a) (i) Give the letter of a compound not shown as a displayed formula. (1) .............................................................................................................................................
(ii) Give the letter of a saturated compound with the general formula CnH2n (1) .............................................................................................................................................
(iii) Name compound E. (1)
.............................................................................................................................................
(iv) Explain why compound A and compound D are isomers. (2) ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. .............................................................................................................................................
(b) Compound F reacts with bromine in the presence of ultraviolet radiation.
(i) Complete the equation for the reaction. (1)
CH4 + Br2 → (ii) Give the name of this type of reaction. (1) .............................................................................................................................................
(d) Compound E is used to make an addition polymer.
(i) Complete the equation to show part of the polymer formed from two molecules of compound E. (2)
(ii) Give one problem caused by the disposal of addition polymers. (1) ............................................................................................................................................. .............................................................................................................................................
(Total for question = 10 marks)
7) (a) (i) Organic compounds can exist as isomers.
Explain what is meant by the term isomers. (2) ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. .............................................................................................................................................
(ii) Organic compound Q reacts with bromine, without the presence of ultraviolet radiation, to form the compound C4H8Br2 Draw the displayed formulae of two isomers of Q.
(b) An acrylic polymer can be formed from molecules with this structure.
(i) A student describes the molecule as an unsaturated hydrocarbon. Explain whether this is a correct description. (2) ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. .............................................................................................................................................
(ii) Name the type of polymerisation that occurs in the formation of the polymer. (1) .............................................................................................................................................
(iii) Complete the equation for the polymerisation reaction. (2)
(ii) State an environmental problem caused by carbon dioxide. (1) ............................................................................................................................................. .............................................................................................................................................
(Total for question = 10 marks)
8) (a) Propene is an alkene with the molecular formula C3H6
(i) Give the general formula for the alkenes. (1) .............................................................................................................................................
(ii) Explain why propene is described as an unsaturated hydrocarbon. (3) ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. .............................................................................................................................................
(b) The polymer poly(chloroethene) has the repeat unit
(i) Draw the displayed formula of the monomer that forms this polymer. (1)
(ii) Explain why there is a problem in the disposal of polymers such as poly(chloroethene). (2) ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. .............................................................................................................................................
(Total for question = 7 marks)
9) This question is about alkanes and alkenes.
(a) (i) Complete the boxes by giving the missing information about the alkane with the molecular formula C2H6 (3)
(ii) Complete the chemical equation for the complete combustion of the alkane C2H6 (1)
...........C2H6 + ...........O2 → ...........CO2 + ...........H2O
(iii) Incomplete combustion occurs when the air supply is limited.
Give the names of two products of incomplete combustion. (2)
1 ..........................................................................................................................................
2 ..........................................................................................................................................
(b) An alkene with molecular formula C4H8 reacts with bromine to form a compound with molecular formula C4H8Br2
(i) What is the name of this type of reaction? (1)
A addition
B decomposition
C precipitation
D substitution
(ii) Draw displayed formulae for two different alkenes with the molecular formula C4H8 (2)
(iii) State the term used for compounds with the same molecular formula but different structural formulae. (1) .............................................................................................................................................
(c) The alkene C3H6 can be polymerised to form the polymer poly(propane).
(i) Complete the equation for this polymerisation reaction. (2)
(ii) Two ways of disposing of polymers such as poly(propene) are • burying them in landfill sites • burning them to release heat energy
Discuss the environmental problems caused by these two methods of disposal. (3) ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. .............................................................................................................................................
(Total for question = 15 marks)
10) Ethanol, C2H5OH, can be manufactured from ethene and steam using a phosphoric acid catalyst.
(a) (i) State the temperature and pressure used in this manufacturing process. (2)
temperature .............................................................................................................................................
pressure .............................................................................................................................................
(ii) Draw the displayed formula of ethanol. (1)
(b) Ethanol burns in a plentiful supply of air to form carbon dioxide and water.
(i) Give the chemical equation for this reaction. (2) .............................................................................................................................................
(ii) When the air supply is limited, incomplete combustion occurs and carbon monoxide forms.
State why carbon monoxide is poisonous to humans. (1) ............................................................................................................................................. .............................................................................................................................................
(c) When ethanol reacts with ethanoic acid, an ester forms.
Give the name of this ester. (1)
.............................................................................................................................................
(d) Butanedioic acid and ethanediol react together to form a polyester and water.
(i) Give the name of this type of polymerisation. (1) .............................................................................................................................................
If you need the markscheme, including the examiners' reports for each question, and more exam and teaching materials on this topic, contact me through the contact page