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7.1 Organic Chemistry – Standard Demand 1 – Questions
Q1.Crude oil is a mixture of many saturated hydrocarbons. They can be separated into fractions by the process of fractional distillation.
State what is meant by:
(i) hydrocarbon. _______________________________________________________
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(ii) saturated. _________________________________________________________
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(iii) fraction. ___________________________________________________________
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(Total 4 marks)
Q2.(a) Methane is burned in a plentiful supply of oxygen.
Which is the correct balanced chemical equation?
Tick one box.
CH4 + O2 → CO2 + H2O
CH4 + 2O2 → CO2 + H2O
CH4 + 2O2 → CO2 + 2H2O
CH4 + 3O2 → 2CO2 + 2H2O
(1)
(b) Burning fuels causes atmospheric pollution.
Write one effect for each pollutant in Table 1.
Table 1
Pollutant Effect
Carbon
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monoxide
Sulfur dioxide
Particulates
(3)
(c) Methane, petrol and coal are fuels.
Table 2 shows information about these fuels.
Table 2
Fuel StateEnergy
content in kJ per g
Mass in mg of CO2
produced for one kJ of energy
released
Methane Gas 52 53
Petrol Liquid 43 71
Coal Solid 24 93
Evaluate the use of the fuels.
Use in the information in Table 2 and your knowledge.
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(Total 10 marks)
Q3.Crude oil is used to produce many useful materials.
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(a) The diagram shows some of the fractions produced from crude oil by fractional distillation.
Use the diagram to help you to explain how crude oil is separated into fractions.
You should use the words evaporated and condensed in your answer.
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(b) The table shows some information about four of the fractions from crude oil that are used as fuels.
Fraction Boiling point in °C Number of carbon atomsfound in the molecules
Gasoline (petrol) 20 - 200 5 - 10
Kerosene (paraffin) 180 - 260 10 - 16
Diesel 260 - 340 14 - 20
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Fuel oil 370 - 600 20 - 70
Use the information in the table to help you to answer these questions.
(i) How can you tell that each of the fractions is a mixture?
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(ii) How does the number of carbon atoms in a molecule affect its boiling point?
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(c) Fuels are substances that release energy.
(i) Name the reaction that releases energy from a fuel such as gasoline (petrol).
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(ii) Describe how fuel oil is broken down into smaller, more useful molecules such as gasoline (petrol).
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(Total 8 marks)
Q4.Crude oil is a mixture of many different chemical compounds.
The table shows information about four compounds that can be obtained from crude oil.
Compound Chemical formula
Melting point in °C
Boiling point in °C
Decane C10H22 –30 +174
Ethene C2H4 –169 –104
Icosane C20H42 +37 +343
Methane CH4 –183 –164
(a) Which compound in the table is a liquid at room temperature (20 °C)?
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Tick one box.
Decane
Ethene
Icosane
Methane
(1)
(b) Which compound in the table has the highest viscosity?
Tick one box.
Decane
Ethene
Icosane
Methane
(1)
(c) Which compound can be used to produce a polymer?
Tick one box.
Decane
Ethene
Icosane
Methane
(1)
(d) The diagram shows the separation of crude oil in a fractionating column.
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Explain how crude oil is separated into different fractions by fractional distillation.
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(Total 9 marks)
Q5.(a) The hydrocarbon C16H34 can be cracked.
Balance the equation for cracking C16H34
C16H34 → ________________ C2H4 + C8H18
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(1)
(b) Describe the differences between cracking and distillation.
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(c) What type of reaction is cracking?
Tick one box.
Combustion
Decomposition
Neutralisation
Precipitation
(1)
(d) Ethene is used to make poly(ethene).
Poly(ethene) is used to make plastic bags.
the table below shows data from a Life Cycle Assessment (LCA) for a plastic bag and a paper bag.
Plastic bag Paper bag
Raw materials Crude oil or natural gas Wood
Energy used in MJ 1.5 1.7
Mass of solid waste in g 14 50
Mass of CO2 produced in kg 0.23 0.53
Volume of fresh water used in dm3 255 4 520
A company stated: ‘A Life Cycle Assessment shows that using plastic bags has less environmental impact than using paper bags’.
Evaluate this statement. Use your knowledge and the information from above the table above.
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(Total 10 marks)
Q6.This question is about hydrocarbons.
(a) Most of the hydrocarbons in crude oil are alkanes.
(i) Large alkane molecules can be cracked to produce more useful molecules.
The equation shows the cracking of dodecane.
Give two conditions used to crack large alkane molecules.
1. ____________________________________________________________
2. ____________________________________________________________(2)
(ii) The products hexene and ethene are alkenes.
Complete the sentence.
When alkenes react with bromine water the colour changes
from orange to _________________________ .(1)
(iii) Butane (C4H10) is an alkane.
Complete the displayed structure of butane.
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(1)
(b) A group of students investigated the energy released by the combustion of four hydrocarbon fuels.
The diagram below shows the apparatus used.
Each hydrocarbon fuel was burned for two minutes.
Table 1 shows the students’ results.
Table 1
After two minutes
Name and formula of hydrocarbon fuel
Mass of fuel used
in g
Temperature increase of water in °C
Energy released by
fuel in kJ
Energy released by 1.0 g of fuel
in kJ
Relative amount of smoke in the flame
Hexane, C6H14 0.81 40 16.80 20.74 very little smoke
Octane, C8H18 1.10 54 22.68 20.62 some smoke
Decane, C10H22 1.20 58 24.36 smoky
Dodecane, C12H26
1.41 67 28.14 19.96 very smoky
(i) Calculate the energy released by 1.0 g of decane in kJ.
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Energy released = ___________________ kJ(2)
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(ii) Suggest one improvement to the apparatus, or the use of the apparatus, that would make the temperature increase of the water for each fuel more accurate.
Give a reason why this is an improvement.
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(iii) The students noticed that the bottom of the beaker became covered in a black substance when burning these fuels.
Name this black substance.
Suggest why it is produced.
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(iv) A student concluded that hexane is the best of the four fuels.
Give two reasons why the results in Table 2 support this conclusion.
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2. ____________________________________________________________
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(c) In this question you will be assessed on using good English, organising information clearly and using specialist terms where appropriate.
Most car engines use petrol as a fuel.
• Petrol is produced from the fractional distillation of crude oil.
• Crude oil is a mixture of hydrocarbons.
• Sulfur is an impurity in crude oil.
Car engines could be developed to burn hydrogen as a fuel.
• Hydrogen is produced from natural gas.
• Natural gas is mainly methane.
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Table 2 shows information about petrol and hydrogen.
Table 2
Petrol Hydrogen
State of fuel at room temperature Liquid Gas
Word equation for combustion of the fuel
petrol + oxygen → carbon dioxide + water
hydrogen + oxygen → water
Energy released from combustion of 1 g of the
fuel47 kJ 142 kJ
Describe the advantages and disadvantages of using hydrogen instead of petrol in car engines.
Use the information given and your knowledge and understanding to answer this question.
(6)(Total 18 marks)
Q7.The diagrams represent two compounds, A and B.
Compound A Compound B
(a) (i) Compound B is an alcohol.
Name compound B.
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(ii) Use the correct answer from the box to complete the sentence.
burned decomposed oxidised
To form compound A,
compound B is ___________________________________(1)
(iii) Compounds A and B are both colourless liquids.
A test tube contains a colourless liquid, which could be either compound A or
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compound B.
Describe a simple chemical test to show which compound, A or B, is in the test tube.
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(b) Compounds A and B react to produce compound C and compound D.
Compound A Compound B Compound C
(i) What is the formula of compound D?
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(ii) Compound C is an ester.
Name compound C.
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(iii) State one use of esters.
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(Total 7 marks)
Q8.Fossil fuels contain carbon and hydrogen.
(a) (i) Use the Chemistry Data Sheet to help you to answer this question.
Complete the figure below to show the electronic structure of a carbon atom.
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(1)
(ii) Complete the word equation for the oxidation of hydrogen.
hydrogen + oxygen ______________________(1)
(b) Coal is a fossil fuel.
Coal contains the elements hydrogen, sulfur, oxygen and carbon.
Name two products of burning coal that have an impact on the environment.
What impact does each of the products you named have on the environment?
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(Total 6 marks)
Q9.This question is about oil reserves.
(a) Diesel is separated from crude oil by fractional distillation.
Describe the steps involved in the fractional distillation of crude oil.
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(b) Diesel is a mixture of lots of different alkanes.
What are alkanes?
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(c) In this question you will be assessed on using good English, organising information clearly and using specialist terms where appropriate.
Petroleum products, such as petrol, are produced from crude oil.The graph shows the possible future production of petroleum products from crude oil and the expected demand for petroleum products.
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Canada’s oil sands hold about 20% of the world’s known crude oil reserves.
The oil sands contain between 10 to 15% of crude oil. This crude oil is mainly bitumen.
In Canada the oil sands are found in the ground underneath a very large area of forest. The trees are removed. Then large diggers and trucks remove 30 metres depth of soil and rock to reach the oil sands. The oil sands are quarried. Boiling water is mixed with the quarried oil sands to separate the bitumen from the sand. Methane (natural gas) is burned to heat the water.
The mixture can be separated because bitumen floats on water and the sand sinks to the bottom of the water. The bitumen is cracked and the products are separated by fractional distillation.
Use the information given and your knowledge and understanding to suggest the advantages and disadvantages of extracting petroleum products from oil sands.
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(Total 11 marks)
Q10.
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Crude oil is a mixture of many different chemical compounds.
(a) Fuels, such as petrol (gasoline), can be produced from crude oil.
(i) Fuels react with oxygen to release energy.
Name the type of reaction that releases energy from a fuel.
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(ii) Fuels react with oxygen to produce carbon dioxide.The reaction of a fuel with oxygen can produce a different oxide of carbon.
Name this different oxide of carbon and explain why it is produced.
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(b) Most of the compounds in crude oil are hydrocarbons.Hydrocarbons with the smallest molecules are very volatile.
In this question you will be assessed on using good English, organising information clearly and using specialist terms where appropriate.
Describe and explain how petrol is separated from the mixture of hydrocarbons in crude oil.
Use the diagram and your knowledge to answer this question.
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(Total 9 marks)
Q11.A mixture of petrol and air is burned in a car engine.Petrol is a mixture of alkanes. Air is a mixture of gases.
The tables give information about the composition of petrol and the composition of air.
Petrol Air
Alkane Formula Gas Percentage (%)
hexane C6H14 nitrogen 78
heptane oxygen 21
octane C8H18 carbon dioxide 0.035
nonane C9H20 Small amounts of other gases and water vapour decane C10H22
(a) Use the information above to answer these questions.
(i) Give the formula for heptane
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(ii) Complete the general formula of alkanes.n = number of carbon atoms
CnH(1)
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(b) Alkanes in petrol burn in air.The equations represent two reactions of hexane burning in air.
Reaction 1 2C6H14 + 19O2 → 12CO2 + 14H2O
Reaction 2 2C6H14 + 13O2 → 12CO + 14H2O
Reaction 2 produces a different carbon compound to Reaction 1.
(i) Name the carbon compound produced in Reaction 2.
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(ii) Give a reason why the carbon compounds produced are different.
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(c) The table shows the percentages of some gases in the exhaust from a petrol engine.
Name of gas Percentage (%)
nitrogen 68
carbon dioxide 15
carbon monoxide 1.0
oxygen 0.75
nitrogen oxides 0.24
hydrocarbons 0.005
sulfur dioxide 0.005
other gases
(i) What is the percentage of the other gases in the table?
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(ii) What is the name of the compound that makes up most of the other gases?
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(iii) Give a reason why sulfur dioxide is produced in a petrol engine.
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(iv) State how nitrogen oxides are produced in a petrol engine.
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(d) Many scientists are concerned about the carbon dioxide released from burning fossil fuels such as petrol.
Explain why.
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(Total 11 marks)
Q12.Petroleum diesel is a fuel made from crude oil.Biodiesel is a fuel made from vegetable oils.To make biodiesel, large areas of land are needed to grow crops from which the vegetable oils are extracted.Large areas of forest are cleared by burning the trees to provide more land for growing these crops.
(a) Use this information and your knowledge and understanding to answer these questions.
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(i) Carbon neutral means that there is no increase in the amount of carbon dioxide in the atmosphere.
Suggest why adverts claim that using biodiesel is carbon neutral.
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(ii) Explain why clearing large areas of forest has an environmental impact on the atmosphere.
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(b) Why is there an increasing demand for biodiesel?
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(c) Suggest why producing biodiesel from crops:
(i) causes ethical concerns
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(ii) causes economic concerns.
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(Total 7 marks)
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Q13.About 3000 million years ago, carbon dioxide was one of the main gases in the Earth’s atmosphere.
About 400 million years ago, plants and trees grew on most of the land. When the plants and trees died they were covered by sand and slowly decayed to form coal.
(a) Describe and explain how the composition of the Earth’s atmosphere was changed by the formation of coal.
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(b) Today, coal is burned in power stations to release the energy needed by industry.Carbon dioxide, water and sulfur dioxide are produced when this coal is burned.
Name three elements that are in this coal.
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(c) In some power stations coal is mixed with calcium carbonate (limestone).The mixture is crushed before it is burned.
(i) Many chemical reactions happen when this mixture is burned.The chemical equation represents one of these reactions.
Balance the chemical equation.
2CaCO3(s) + 2SO2(g) + O2(g) → ………CaSO4(s)
+ ………CO2(g)
(1)
(ii) Explain how the use of calcium carbonate in the mixture:
increases atmospheric pollution
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decreases atmospheric pollution.
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(Total 10 marks)
Q14.There are two main types of diesel fuel used for cars:
• biodiesel, made from vegetable oils
• petroleum diesel, made from crude oil.
(a) A scientist compared the viscosity of biodiesel with petroleum diesel at different temperatures.The scientist measured the time for the same volume of diesel to flow through a small hole in a cup.The scientist’s results are plotted on the grid.
(i) Draw a line of best fit for the biodiesel results.(1)
(ii) What conclusions can the scientist make about the viscosity of biodiesel compared with the viscosity of petroleum diesel at different temperatures?
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(iii) Biodiesel may be less suitable than petroleum diesel as a fuel for cars.Use these results to suggest one reason why.
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(b) Biodiesel can be mixed with petroleum diesel to make a fuel for cars.In a car engine, the diesel fuel burns in air.The waste products leave the car engine through the car exhaust system.The bar chart compares the relative amounts of waste products made when three different types of diesel fuel burn in a car engine.
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Nitrogen oxides and sulfur dioxide cause a similar environmental impact.
(i) What environmental impact do particulates from car exhaust systems cause?
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(ii) What is the percentage reduction in particulates when using B100 instead of petroleum diesel?
_____________________ %(1)
(iii) Replacing petroleum diesel with biodiesel increases one type of environmental pollution.
Use the bar chart and the information given to explain why.
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(iv) A carbon neutral fuel does not add extra carbon dioxide to the atmosphere.
Is biodiesel a carbon neutral fuel?
Use the bar chart and your knowledge to explain your answer.
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(Total 10 marks)
Q15.Crude oil is a mixture of hydrocarbons. Most of these hydrocarbons are alkanes.
(a) The general formula of an alkane is CnH2n+2
Complete the structural formula for the alkane that has six carbon atoms in its molecules.
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(1)
(b) The boiling points of alkanes are linked to the number of carbon atoms in their molecules.
(i) Describe the link between the number of carbon atoms in an alkane molecule and its boiling point.
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(ii) Suggest two reasons why all of the alkanes in the bar chart are better fuels than the alkane with the formula C30H62
1. ____________________________________________________________
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2. ____________________________________________________________
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(c) During the last 200 million years the carbon cycle has maintained the percentage of carbon dioxide in the atmosphere at about 0.03 %.Over the last 100 years the percentage of carbon dioxide in the atmosphere has increased to about 0.04 %.Most of this increase is caused by burning fossil fuels to heat buildings, to generate electricity and to power our transport.Fossil fuels contain carbon that has been locked up for millions of years.
(i) Burning fossil fuels, such as petrol, releases this locked up carbon. Balance the chemical equation for the combustion of one of the alkanes in petrol.
2 C8H18 + 25 O2 ____ CO2 + ____ H2O
(1)
(ii) Where did the carbon that is locked up in fossil fuels come from?
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(iii) The burning of fossil fuels has caused the percentage of carbon dioxide in the atmosphere to increase to above 0.03 %.Explain why.
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(Total 8 marks)
Q16.(a) Alkanes are important hydrocarbon fuels. They have the general formula CnH2n+2
The points on the graph show the amount of energy released when 1 mole of methane (CH4), ethane (C2H6), propane (C3H8) and butane (C4H10) are burned separately.
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(i) Draw a line through the points and extend your line to the right-hand edge of the graph.
(1)
(ii) Use the graph to estimate the amount of energy released when 1 mole of octane (C8H18) is burned.
Energy released = ____________________ kJ(1)
(iii) Suggest why we can make a good estimate for the energy released by 1 mole of pentane (C5H12).
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(iv) A student noticed that octane (C8H18) has twice as many carbon atoms as butane (C4H10), and made the following prediction:
“When burned, 1 mole of octane releases twice as much energy as 1 mole of butane.”
Use the graph to decide if the student’s prediction is correct. You must show your working to gain credit.
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(b) Some information about four fuels is given in the table.
Combustion products
Fuel Type Heat released in kJ per g
CO2 SO2 H2O Type of flame
Bio-ethanol Renewable 29 Not smoky
Coal Non-renewable 31 Smoky
Hydrogen Renewable 142 Not smoky
Natural gas Non-renewable 56 Not smoky
From this information a student made two conclusions.
For each conclusion, state if it is correct and explain your answer.
(i) “Renewable fuels release more heat per gram than non-renewable fuels.”
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(ii) “Non-renewable fuels are better for the environment than renewable fuels.”
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(Total 9 marks)
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Q17.Crude oil is a resource from which fuels can be separated.
(a) The name of the main fuel fractions and one of the hydrocarbons in each fraction are shown in the table.
(i) How does the number of carbon atoms in a hydrocarbon affect its boiling point?
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(ii) Suggest the lowest temperature to which crude oil needs to be heated to vaporize all the hydrocarbons in the table.
Temperature = ________________________ °C(1)
(iii) Dodecane boils at 216 °C. At what temperature will dodecane gas condense to liquid?
Temperature = ________________________ °C(1)
(b) The bar chart shows the relative supply and demand for the petrol and diesel fractions.
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(i) How does the relative supply and demand for petrol and diesel fractions cause problems for an oil company?
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(ii) Suggest one way an oil company could solve these problems.
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(Total 6 marks)
Q18.The hydrocarbons in crude oil can be separated into useful fractions.
Fraction Boiling pointin °C
Carbonchain length
Relative %in crude oil
Relative %demand
Naphtha 20–180 5–9 10 20
Gasoline (petrol) 20–200 5–10 10 20
Kerosene (paraffin) 180–260 10–16 15 23
Diesel 260–340 14–20 20 25
Fuel oil 370–600 20–70 45 12
(a) Why does gasoline (petrol) have a lower boiling point than fuel oil?
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(1)
(b) Suggest why gasoline (petrol) costs more than fuel oil.
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(c) Describe how fuel oil can be changed into gasoline (petrol).
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(Total 5 marks)
Q19.The diagram shows an apparatus that can be used to carry out cracking reactions in a laboratory.
(a) Why is aluminium oxide or broken porcelain used?
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(b) Paraffin contains decane. The cracking of decane can be represented by the equation below. A decane molecule is split into two smaller molecules.
Complete the equation by adding the formula of the other product.
C10H22 (l) →__________ (l) + C2H4 (g)decane
(1)
(c) Would you expect C2H4 molecules to collect at position A or B shown on the diagram?
Position ______________ .
Explain your answer.
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(d) Cracking reactions involve thermal decomposition.
What is meant by thermal decomposition?
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(e) Explain, as fully as you can, why cracking is used in the oil industry.
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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(f) The cracking reaction produces a mixture of products. The mixture contains hydrocarbons with different boiling points.
Suggest a method of separating this mixture.
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(Total 9 marks)
Q20.The table gives some data about four fuels, A, B, C and D.
Fuel
Cost in pence
per
Energy in kJ per
Energy per
penny in Gas ( ) formed on burning
100 g 100 g kJ Carbon dioxide
Sulphur dioxide
Water vapour
A 6.0 4 800 800
B 4.0 1 200 300
C 3.5 2 800 800
D 18.0 14 400 800
A student was asked to use the data in the table to compare these four fuels, and then place the fuels in an order.
The order that the student chose was:
Use the information in the table to suggest reasons why the student chose this order.
To gain full marks in this question you should write down your ideas in good English. Put them into a sensible order and use the correct scientific words.
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Q21.To make crude oil more useful it is separated into different fractions.
(a) Complete the gaps in the following sentences.
Crude oil is separated into different fractions by a process called ______________
_________________ . Each fraction has a different ________________________ .(2)
(b) Each fraction is a mixture of compounds. Most of these compounds are hydrocarbons, made up of the elements hydrogen and carbon.
(i) Explain the difference between a mixture and a compound.
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(2)
(ii) Explain the difference between a compound and an element.
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(Total 6 marks)
Q22.Crude oil is a mixture of a large number of compounds most of which are hydrocarbons such as the molecule shown below.
(a) What is a hydrocarbon?
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(b) What is the chemical formula of the molecule shown above?
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(c) The cracking of large molecules obtained from crude oil is one of the important processes in an oil refinery. Cracking involves the thermal decomposition of large molecules. The diagram below shows an apparatus that can be used to demonstrate cracking in the laboratory. The porous pot acts as a catalyst in the reaction.
(i) What happens during thermal decomposition?
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______________________________________________________________
______________________________________________________________(2)
(ii) What effect does the porous pot catalyst have on the reaction?
______________________________________________________________
______________________________________________________________(1)
(iii) Complete the equation below for the cracking of the molecule. C20H42.
C20H42 → C12H26 + ______________________(1)
(Total 6 marks)
Q23.Methane CH4 contains the elements carbon and hydrogen only. A student wanted to find out which new substances are produced when methane is burned. The student set up the apparatus shown below.
(a) Which gas in the air reacts with methane when it burns?
___________________________________________________________________(1)
(b) Name the liquid collected.
___________________________________________________________________(1)
(c) Name the gas which turns limewater milky.
___________________________________________________________________(1)
(d) When methane burns an exothermic reaction takes place. What is meant by an exothermic reaction?
___________________________________________________________________
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___________________________________________________________________(2)
(Total 5 marks)
Q24.Crude oil is a complex mixture of hydrocarbons, mainly alkanes. The number of carbon atoms in the molecules ranges from 1 to over 100.
(a) How does the boiling point change as the number of carbon atoms in the molecules increases?
___________________________________________________________________
___________________________________________________________________(1)
(b) Name the method used to separate petroleum into fractions.
___________________________________________________________________(1)
(c) The simplest hydrocarbon is methane, CH4. Its structure can be represented:
Draw the structure of ethane, C2H6.(1)
(Total 3 marks)
Q25.Diesel oil is obtained from crude oil. It can be used as a fuel for car engines. The diagram below represents a compound found in diesel oil.
(a) What is the formula of this compound?
___________________________________________________________________(1)
(b) Each of the lines on the diagram above represents a covalent bond.
What is a covalent bond?
___________________________________________________________________
___________________________________________________________________
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(2)(Total 3 marks)
Q26.(a) Crude oil is a mixture of many compounds. Most of the compounds consist of
molecules made only of carbon and hydrogen. Choose one word from the list below to complete the sentence.
carbohydrates carbonates hydrocarbons hydrogencarbonates
Compounds made only of carbon and hydrogen are called ____________________(1)
(b) The fractions contain molecules with similar numbers of carbon atoms. The main fractions are shown in the table below.
NAME OF FRACTION NUMBER OF CARBON ATOMS IN MOLECULES
petroleum gases
gasoline
naphtha
kerosene
diesel oil
lubricating oil
residue
1 to 4
4 to 12
7 to 14
11 to 15
14 to 19
18 to 30
more than 30
Naphtha burns more easily than diesel oil.Explain why.
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________(1)
(Total 2 marks)
Q27.Propane has a small, hydrocarbon molecule, so it is used as a fuel.
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(a) Complete the sentences by choosing the correct words from the box.
carbohydrate high hydrogen
hydroxide low volatile
Propane is a hydrocarbon with a __________________ boiling point. Propane is a
hydrocarbon because it is made of _________________ and carbon only.(2)
(b) Describe, in as much detail as you can, what happens when propane burns.
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________(3)
(Total 5 marks
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