Organic chemistry

Revision/ Organic chemistry Page 1

ORGANIC CHEMISTRY

G.C.E O’ LEVEL 5070

Multiple choice questions

1 The structures of an acid and an alcohol are shown.

Which pairing of names correctly identify the two compounds?

Acid alcohol

A ethanoic butanol

B ethanoic propanol

C propanoic propanol

D propanoic butanol

2 Which physical property of the alkanes does not increase as relative molecular

mass increases?

A boiling point B flammability

C melting point D viscosity

37 The structures of four organic compounds are shown.

Which compounds decolourise bromine water?

A 1 and 2 B 1, 2 and 4 C 2 and 4 D 3 and 4


3 A polymer X was hydrolysed and the two products were

What can be deduced about X?

A It was a condensation polymer B It was starch.

C It was made by addition polymerisation. D It was Terylene.

4 Which polymer has the empirical formula CH?

5 In the polymerisation of ethene to form poly(ethene), there is no change in

A boiling point. B density.

C mass. D molecular formula.

6 The macromolecules of proteins, fats and carbohydrates can all be broken down

into their simple units by a similar process.

What is the process called?

A esterification B hydrolysis C oxidation D reduction


7 The repeating units of two polymers, X and Y, are shown below.

What are X and Y?

X Y

nylon terylene

starch terylene

protein starch

nylon protein

8 The table shows the results of tests carried out on compound X.

Test resul

Bromine water added decolourised

Sodium carbonated added Colourless gas evolved

Which formula represents compound X?


9 Butane and methylpropane are isomers.

Which formula is different for the two isomers?

A empirical formula B general formula

C molecular formula D structural formula

10 What is the general formula of the homologous series of carboxylic acids?

Methanoic acid HCO2H

Ethanoic acid CH3CO2H

Propanoic acid C2H5CO2H

Butanoic acid C3H7CO2H

A CHO B CnH2nO C CnHnOn D CnH2nO2

11 A section of a polymer is shown.

The monomer undergoes condensation polymerisation. What is made each time a

monomer adds to the polymer?

A hydrogen molecules, H2 B hydroxide ions, OH-

C oxygen atoms, O D water molecules, H2O

12 The experiment shown is carried out.


What process occurs?

A cracking B dehydrogenation

C distillation D polymerisation

13 What is produced when ethanol is boiled with an excess of acidified potassium

dichromate(VI)?

A ethane B ethanoic acid

C ethane D ethyl ethanoate

14 When 1 volume of gas X reacts with exactly 5 volumes of oxygen it forms carbon

dioxide and water only.

What is gas X?

A methane, CH4 B ethane, C2H6

C propane, C3H8 D butane, C4H10

15 Which structure shows a compound that reacts with ethanol to give a sweet-

smelling liquid?

16 The tables shows the properties of four compounds.

Which compound could be ethanoic acid?

comp

ound

Degree of ionization in water Addition of aqueous solution of the

compound to magnesium

A high Hydrogen produced

B high No reaction

C low Hydrogen produced

D low No reaction


17 Amino acids are produced when proteins are

A hydrolysed. B oxidised.

C polymerised. D substituted.

18 The table shows the energy released by the complete combustion of some

compounds used as fuels.

Which fuel produces the most energy when 1

g of the compound is completely burned?

A ethanol B heptane C methane D propane

19 Poly(ethene) can be manufactured by the process below.

Which diagram shows the change in molecular size during this process?

20 Compound Q has the structure shown.


Which structure is an isomer of Q?

21 Compound X has the molecular formula C2 H6O.

• X can be made by a fermentation process.

• X can be oxidised to Y.

• X can react with Y to form Z and water.

To which homologous series do X, Y and Z belong?

X Y Z

A alcohols carboxylic acids esters

B alcohols esters carboxylic acids

C carboxylic acids alcohols esters

D carboxylic acids esters alcohols

22 The list shows reactions in which ethanol is either a reactant or a product.

In which reactions is water also either a reactant or a product?

A 1, 3 and 4 only B 2, 3 and 4 only

C 1, 2 and 4 only D 3 only


23 A vegetable oil is polyunsaturated.

Which statement about this vegetable oil is correct?

A It has double bonds between carbon and hydrogen atoms.

B It reacts with hydrogen to form a solid compound.

C It reacts with steam to form margarine.

D It turns aqueous bromine from colourless to brown.

24 'Cracking' of hydrocarbons break them into smaller molecules.

Which example of 'cracking' would produce the largest volume of products from one

mole of hydrocarbon? Assume that all measurements are made at the same

temperature and pressure.

A C6H14(g) 3C2H4+H2(g) B C8H18(g) 2C3H8+H2(g)

C C10H22(g) 3C8H18+C2H4(g) D C12H26(g) 3C8H18(g) +2C2H4(g)

1 Chlorofluorocarbons (CFCs) are sometimes used as propellants in aerosols.

‘Holes’ in the ozone layer are caused by reactions involving chlorofluorocarbons.

(a) Explain why holes in the ozone layer can cause harm to humans.

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

Difluoromethane, CH2F2 s a hydrofluorocarbon.

It can be used instead of CFCs in aerosols.

(b) Draw a dot and cross diagram to show the bonding in CH2F2

Your diagram only needs to show outer shell electrons.

(c) Difluoromethane can be made by reacting methane with fluorine.

CH4+ F2→CH3F + substance X

CH3F + F2→ CH2F2+ substance X


(i) Name substance X.

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

(ii) What is the name for this type of reaction?

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

(iii) Gaseous bromine will also react with methane.

Suggest whether the reaction is faster or slower than with fluorine.

Explain your answer.

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

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

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

2 This is the structure of an ester made in a reversible reaction between a carboxylic

acid and an alcohol.

(a) (i) State the conditions for this reaction.

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

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

(ii) Draw the structure of the carboxylic acid used in the reaction.

(iii) Write an equation for this reaction.

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

(b) A student carried out some experiments to compare the relative strengths of

dilute ethanoic acid with dilute hydrochloric acid.

(i) Describe a test that can be used to distinguish between dilute ethanoic acid and

dilute hydrochloric acid.

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

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


(ii) Name a solid substance that will react with both acids. Describe what you will see

during the reaction.

Substance ……………………………………………………………………………………..

Observation……………………………………………………………………………………

3 Ethanol, CH3CH2OH, is a liquid fuel. Ethanol can be manufactured either from

glucose,C6H12O6 or from ethene.

(a) Briefly describe the manufacture of ethanol from glucose.

Include the balanced equation in your answer.

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

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

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

(b) (i) Draw the displayed formula for ethene.

(ii) Name the substance that reacts with ethene to make ethanol.

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(iii) Give the conditions needed for this reaction.

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4 Petroleum is a complex mixture of hydrocarbons. Petroleum is a source of many

useful fuels.

(a) What is meant by the term hydrocarbon?

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

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

(b) Petroleum is separated by fractional distillation.

(i) Complete the following table about the fractions obtained from petroleum.

Fraction Use

Petrol (gasoline) Fuel for cars

Paraffin (kerosene)

Diesel Fuel for diesel engines

bitumen


(ii) Name one other fraction obtained from petroleum.

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

(c) Fractional distillation of petroleum does not produce sufficient of some fractions

to match demand.

Cracking is used to convert large hydrocarbon molecules into smaller molecules that

are more in demand.

A hydrocarbon of molecular formula C12H26 fuel for cars fuel for diesel engines is

cracked.

(i) Suggest the formula of one alkane that may be produced.

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

(ii) Suggest the formula of one alkene that may be produced.

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

(iii) Describe a chemical test that can be used to distinguish between an alkene and

an alkane.

chemical test .............................................................................................................

(iii) Describe a chemical test that can be used to distinguish between an alkene and

an alkane.

chemical test .................................................................................................................

result with alkane ..........................................................................................................

result with alkene ......................................................................................................[4]

5 Carbon dioxide is a greenhouse gas. Carbon dioxide is given a greenhouse factor

of 1. Other gases are given a greenhouse factor that compares their effect with

carbon dioxide. The greenhouse effect increases as the factor value increases. The

table gives some information about four different gases.

gas Greenhouse factor Percentage of gas in the

atmosphere

CO2 1 0.036

CH4 30 0.0017

N2O 160 3.0x10-4

CCl3F 21000 2.8x10-8

(a) State one possible consequence of an increased greenhouse effect.

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


(b) Give one source of methane.

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

(c) Why is an increase in the percentage of methane more worrying than the same

percentage increase of carbon dioxide?

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

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

(d) What other environmental problem, beside its action as a greenhouse gas, is caused by

CCl3F?

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

6 Methane, CH4, is used as a fuel. The complete combustion of methane can be

represented by the equation below

(a) Explain why this reaction is exothermic in terms of the energy changes that take

place during bond breaking and bond making.

…………………………………………………………………………………………………

…………………………………………………………………………………………………

………………………………………………………………………………………………[3]

(b) Calculate the energy released when 4.0 g of methane is completely combusted.

…………………………………………………………………………………………………

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

(c) Draw the energy profile diagram for the complete combustion of methane.

Label on the diagram the activation energy and the enthalpy change.

[3]


(d) Draw a ‘dot and cross’ diagram to show the bonding in methane.

You only need to draw the outer (valence) electrons of carbon.

[2]

7 Coal-burning power stations produce sulphur dioxide and oxides of nitrogen.

These two gases cause acid rain.

(a) Nitric oxide, NO, is made in a power station when nitrogen and oxygen react

together.

Write the equation for this reaction.

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

(b) Many coal burning power stations are now fitted with a flue gas desulphurisation

plant which removes sulphur dioxide and nitrogen dioxide from the gaseous

emissions.

In a flue gas desulphurisation plant, powdered calcium carbonate reacts with sulphur

dioxide as shown.

(i) Suggest why the calcium carbonate is powdered.

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

(ii) Calculate the mass of calcium carbonate needed to react with 8000 kg of sulphur

dioxide.

…………………………………………………………………………………………………

…………………………………………………………………………………………………

…………………………………………………………………………………………………

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

(iii) Nitrogen dioxide also reacts with calcium carbonate. Suggest the name of the

solid product of this reaction.

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

(c) In the air sulphur dioxide reacts with nitrogen dioxide forming sulphur trioxide.

The reactions that take place are shown in the equations.


Suggest the role of nitrogen dioxide in these reactions. Explain your answer.

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

Sulphur dioxide is used in the Contact process to make sulphuric acid.

Describe the conditions and name the catalyst in the Contact process.

……………………………………………………………………………………………….....

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

8 Styrene-butadiene rubber is a synthetic rubber. It is made by polymerising a

mixture of the

monomers butadiene and styrene.

(a) What type of polymerisation will take place when the monomers polymerise?

Explain your reasoning.

…………………………………………………………………………………………………

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

One possible structure for the polymer is shown below

(b) Give the full structural formula for the repeating unit in this polymer structure.

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

(c) When the mixture of styrene and butadiene polymerises, the polymer is unlikely

to contain only this regular, repeating pattern. Explain why.

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

Butadiene can be made by cracking butane in a cracking tower.

(d) (i) Butane cracks to form butadiene and one other product.

Write an equation to show this reaction.

………………………………………………………………………………………………[1]

(ii) Give a use of the other product of this reaction.

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


(e) 2.90 kg of butane entered the cracking tower. After the reaction, 2.16 kg of

butadiene had been made.

Calculate the percentage yield of butadiene.

[3]

9 These diagrams show sections of the polymer chain of two condensation

polymers.

(a) (i) Draw a circle around an amide linkage in the diagram. Label this amide.

(ii) Draw a circle around an ester linkage in the diagram. Label this ester. [2]

(b) Name a type of naturally occurring polymer that has a similar linkage to nylon.

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

(c) The formulae of the two monomers used to make nylon are shown below.

Nylon monomer HOOC(CH2)4COOH H2N(CH2)6NH2

Terylene monomer

[2]


(d) Sea fishing nets used to be made from natural fibres. Many nets are now made

from

nylon. Suggest one advantage, other than strength, and one disadvantage of using

nylon rather than natural fibres to make sea fishing nets.

advantage......................................................................................................................

disadvantage ................................................................................................................

[Total: 7 marks]

10This table shows some information about two homologous series; the alkanes and

the acid chlorides.

Use the information in the table to answer the following questions.

(a) Name the acid chloride with the highest boiling point.

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

(b) Deduce the name of the acid chloride with the formula C2H5COCl.

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

(c) The general formula for alkanes is Cx H(2x + 2)

Deduce the general formula for acid chlorides.

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

(d) (i) Name the products of the complete combustion of an alkane.

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

(ii) Would you expect the products of complete combustion of the acid chlorides to

be the same as in (i)? Explain your reasoning.

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

[Total: 5 marks]


11 Petroleum is a mixture of hydrocarbons. In an oil refinery it is separated into

fractions by fractional distillation.

The diagram shows a fractionating column and some of the fractions obtained from

petroleum.

(a) State the physical property on which the separation depends.

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

(b) (i) State one use for the naphtha fraction.

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

(ii) State one use for the bitumen fraction.

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

(c) The liquefied petroleum gas fraction contains the saturated hydrocarbons

methane, CH4 and ethane, C2 H6

(i) What is the meaning of the term saturated hydrocarbon?

…………………………………………………………………………..………………………

…………………………………………………………………………………………………..

(ii) Draw a ‘dot and cross’ diagram to show the bonding in methane. You only need

to draw the outer electrons of carbon

[4]


(d) Describe the importance of cracking in the oil refining process.

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

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

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

12 Ozone, O3, is an atmospheric pollutant in the lower atmosphere but is beneficial

higher up in the atmosphere.

(a) How is ozone formed in the lower atmosphere?

…………………………………………………………………………………………………

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

(b) Ozone in the upper atmosphere is being depleted. Describe briefly how this is

happening and some of the health problems caused by ozone depletion.

…………………………………………………………………………………………………

…………………………………………………………………………………………………

………………………………………………………………………………………………[3]

(c) At room temperature ozone decomposes slowly to form oxygen, O2 .The

decomposition can be represented by the equation below. The reaction is

exothermic. One mole of ozone will release 143 kJ when it is fully decomposed.

2O3 → 3O2

(i) In terms of the energy changes that take place during bond breaking and bond

making, explain why this reaction is exothermic.

…………………………………………………………………………………………………

…………………………………………………………………………………………………

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

(ii) Explain why the rate of this decomposition increases as the temperature

increases.

…………………………………………………………………………………………………

…………………………………………………………………………………………………

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

(iii) Calculate the energy released when 16 g of ozone is decomposed.

…………………………………………………………………………………………………

…………………………………………………………………………………………………

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

Education

Organic chemistry