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7.1 Organic Chemistry – Standard Demand 2 – Questions

Q1.(a) Some hydrocarbons are used as fuels in power stations.

The table gives the boiling points of four hydrocarbons.

Hydrocarbon Boiling point in °C

W 165

X –160

Y –40

Z 180

(i) Which of these hydrocarbons are gases at room temperature (20 °C)?

______________________________________________________________(1)

(ii) Which of these hydrocarbons has the largest molecules?

______________________________________________________________(1)

(iii) Which of these hydrocarbons ignites most easily?

______________________________________________________________(1)

(b) Some hydrocarbons are used to produce polymers.

Which type of hydrocarbons can be converted into polymers?

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(Total 4 marks)

Q2.Crude oil is separated into fractions by fractional distillation.

The table gives information about some of the fractions.

Fraction Boiling point

range in °C

Number ofcarbon atomsper molecule

Gas Below 20 1 – 4

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Petrol 20 – 100 5 – 10

Paraffin 100 – 250 11 – 15

Diesel 250 – 350 16 – 20

Lubricant 350 – 500 21 – 35

Bitumen Above 500 Above 35

(a) What is the relationship between the boiling point of a fraction and the number of carbon atoms in its molecules?

______________________________________________________________

______________________________________________________________(1)

(b) Give one further difference, other than boiling point, between diesel and paraffin that also depends on the number of carbon atoms in their molecules.

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______________________________________________________________(1)

(c) All the fractions contain hydrocarbons.

Name the two elements in a hydrocarbon.

________________ and ________________(1)

(Total 3 marks)

Q3.(a) A piece of lithium is placed on the surface of some water in a beaker.

Hydrogen is given off.Lithium hydroxide is also formed.

Write a word equation for this reaction.

___________________________________________________________________(2)

(b) The diagram shows the structure of a molecule of methane.

Write down everything that this diagram tells you about a methane molecule.

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To gain full marks in this question you should write your ideas in good English. Put them into a sensible order and use the correct scientific words.

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(Total 6 marks)

Q4.The table shows some of the products which are obtained from the fractional distillation of crude oil.

Fraction Nature of products

A a mixture of gases

B a mixture of low boiling point liquids

C a mixture of high boiling point, yellow liquids

(a) For each of the fractions A–C give the name of an organic substance which could be part of the fraction and state a use for it.

A ___________________________________

Use _______________________________________________________________(2)

B ___________________________________

Use _______________________________________________________________(2)

C ___________________________________

Use _______________________________________________________________(2)

(b) When burned in excess air, all the substances in fractions A–C form the same two compounds.

Give the formulae of these two compounds.

______________________________ and _________________________________

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(1)(Total 7 marks)

Q5.Petrol burns in oxygen from the air in a car engine.

Two of the gases in the exhaust fumes are carbon dioxide and water vapour.

This indicates that petrol contains the elements ______________________ and

____________________________ .(Total 2 marks)

Q6.In a car engine petrol burns in oxygen from the air. Two of the gases in the exhaust fumes are carbon dioxide and water vapour.

This indicates that petrol contains the elements ______________ and ______________(Total 2 marks)

Q7.Here is the word equation for a chemical reaction.

methane + oxygen → water + carbon dioxide

Write down everything that the word equation tells you about the reaction.

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_______________________________________________________________________(Total 4 marks)

Q8.The equation below shows the cracking of a hydrocarbon compound into two different compounds, A and B.

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(a) State two differences between the structures of compounds A and B.

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(b) Why is compound A useful in industry?

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(Total 3 marks)

Q9.The structural formulae of two saturated hydrocarbons are shown below.

Describe two ways in which they will differ in their physical properties.

1. _____________________________________________________________________

_______________________________________________________________________

2. _____________________________________________________________________

_______________________________________________________________________(Total 2 marks)

Q10.The table gives some information about a family of molecules in crude oil.

NUMBER OF CARBON ATOMSIN MOLECULE

MASS OF MOLECULE(atomic units)

1 16

2 30

4 58

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(a) Show information from the table in the most appropriate way on the grid.

(3)

(b) What is the mass of a molecule with three carbon atoms?

___________________________________________________________________(1)

(c) The other atoms in each molecule are all hydrogen atoms.What family of substances do all the molecules belong to?

___________________________________________________________________(1)

(d) The mass of a carbon atom is 12 atomic units.The mass of a hydrogen atom is 1 atomic unit.

So the molecule with one carbon atom has four hydrogen atoms.Its formula is CH4.

Write down the formula:

(i) of the molecule with two carbon atoms ___________

(ii) of a molecule from the same family with five carbon atoms ___________(2)

(Total 7 marks)

Q11.The table shows how much carbon dioxide is produced when you transfer the same amount of energy by burning coal, gas and oil.

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(a) Use the information from the table to complete the bar-chart.(3)

(b) The second bar-chart shows how much sulphur dioxide is produced by burning the same three fuels.

Compare the amount of sulphur produced by burning gas with the amount produced by burning coal.

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(c) (i) Coal and oil produce carbon dioxide and sulphur dioxide when they burn.What elements must they contain?

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(ii) Burning fuels also produce nitrogen oxides, even though the fuels contain no nitrogen. Explain why this happens.

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(Total 9 marks)

Q12.Many fuels are produced from crude oil.

(a) Crude oil is separated into fractions by distillation in a fractionating column.

A fractionating column is shown below.

(i) Describe how crude oil is separated into fractions by fractional distillation.

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______________________________________________________________(3)

(ii) Some properties of hydrocarbons change as the size of the molecules increases.

Describe the trends in boiling point and viscosity as the number of carbon atoms in the molecule increases.

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Boiling point ____________________________________________________

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Viscosity ______________________________________________________

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(b) LPG (liquefied petroleum gas) is a fuel. LPG contains propane (C3H8).

(i) Complete the displayed (structural) formula for propane.

(1)

(ii) Burning fuels releases energy. Name two products formed when LPG is burnt.

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______________________________________________________________(2)

(iii) Some cars are now designed to use LPG as a fuel. LPG is about 50p per litre cheaper than petrol.

Suggest one reason why most car owners use cars designed to use petrol and not LPG as a fuel.

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______________________________________________________________(1)

(Total 9 marks)

Q13.Figure 1 shows some Australian bank notes. In Australia, bank notes are made of poly(propene) not paper.

Figure 1

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© Max Blain/Hemera/Thinkstock

(a) Complete Figure 3 to show the structure of poly(propene).

Figure 3

Poly(propene)

(2)

(b) Propene is an alkene.Describe a test that can be done to show that an alkene is present.

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(Total 4 marks)

Q14.Fire dancers use firesticks to make flame patterns.

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One end of the firestick is soaked in kerosene.The kerosene is lit and burns with a yellow flame.

(a) Kerosene is a mixture of hydrocarbons.

Which elements are present in a hydrocarbon?

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___________________________________________________________________(1)

(b) A student investigated the products formed when kerosene burned.

The diagram shows the apparatus the student used.

Describe and explain the observations you would expect the student to make.

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(Total 5 marks)

Q15.Ethene is an alkene.

(a) The general formula of alkenes is CnH2n

An ethene molecule has two carbon atoms.

What is the molecular formula of ethene?

___________________________________________________________________(1)

(b) Ethene is produced in industry from hydrocarbons.

(i) Use words from the box to complete the sentence.

bromine catalyst fuel polymer steam

Hydrocarbons are obtained from the fractional distillation of crude oil.

To produce ethene, the hydrocarbons are vaporised.

The vapours are then passed over a hot __________________________

or mixed with __________________________ and heated to a very high

temperature.(2)

(ii) Complete the following sentence.

The industrial process used to make ethene is called ___________________ .(1)

(c) 8 billion plastic bags are used each year in the UK.

Most plastic bags are made from poly(ethene), but some modern plastic bags are made from polylactic acid (PLA).PLA is a polymer made from cornstarch.Cornstarch comes from maize, a plant crop.

(i) PLA causes fewer problems with waste disposal compared with poly(ethene).

Explain why.

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(ii) PLA and poly(ethene) are made from different raw materials.

Besides waste disposal, suggest one other environmental advantage of using PLA rather than poly(ethene) to make plastic bags.

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(iii) Suggest one disadvantage of using cornstarch to make PLA.

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(Total 8 marks)

Q16.The diagram shows apparatus used to measure the effect of temperature on the viscosity of two liquid hydrocarbons A and B.

The time taken for the steel ball to fall between the two measuring marks is recorded for each hydrocarbon at different temperatures.

(a) Using the stirrer improved the accuracy of the results.

Explain how.

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(b) The graph shows the results of the investigation.

(i) What conclusions can be drawn from the data?

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(ii) Give one reason for the difference in the viscosities of hydrocarbon A and hydrocarbon B.

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(Total 5 marks)

Q17.Hydrocarbons are cracked to produce smaller molecules.

The diagram shows an experiment to demonstrate cracking.

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Describe the process of cracking shown in the diagram.

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Q18.A burning torch is carried by a runner.

The fuel in the torch is a mixture of propane and butane.

Propane and butane are alkanes.

Alkanes have the general formula CnH2n+2

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(a) Propane has 3 carbon atoms.

What is the formula of propane?

___________________________________________________________________(1)

(b) Butane has the formula C4H10

Complete the displayed (structural) formula for one molecule of butane.

(1)

(c) Complete the word equation for the complete combustion of butane.

butane + oxygen → ____________________ + ______________________(1)

(d) In earlier designs of the torch, propene (C3H6) was used as the fuel.

Smoke is produced when propene is burned.

Explain why smoke is produced.

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___________________________________________________________________(2)

(Total 5 marks

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