C7 Organic Chemistry 35 Questions Name: Class: Date: Time: Marks: Comments: Page of 5
The apparatus in the figure below is used to separate a mixture of liquids in a fuel. (a) What is apparatus W on above the figure above? Tick one box. Beaker Boiling Tube Flask Jug () (b) What is the name of this method of separation? Tick one box. Crystallisation Electrolysis Filtration Distillation () Page 2 of 5
(c) Name the changes of state taking place at A and B in the figure above. Use words from the box. boiling condensing freezing melting Change of state at A: Change of state at B: (2) (d) Table shows the boiling points of the hydrocarbons in the fuel. Table Hydrocarbon Boiling point in C Pentane 36 Hexane 69 Heptane 98 Octane 25 Which hydrocarbon will be the last to collect in the beaker? Tick one box. Pentane Hexane Heptane Octane () Page 3 of 5
(e) The fuel is a mixture of liquids that has been designed as a useful product. What name is given to this type of mixture? Tick one box. Catalyst Formulation Polymer Solvent () (f) Describe how this fuel is different from crude oil. (2) (g) A student measured the melting point of a solid hydrocarbon four times. The student s results are in Table 2. Table 2 Trial Trial 2 Trial 3 Trial 4 Melting point in C 35 48 37 37 Calculate the mean melting point of the hydrocarbon, leaving out any anomalous result. Give your answer to two significant figures. Mean melting point = C (2) (Total 0 marks) Page 4 of 5
2 A student investigated the substances produced when fuels burn. The figure below shows the apparatus the student used. (a) The complete combustion of a hydrocarbon produces carbon dioxide and one other substance. Look at the figure above. What would the student see in tube A? () (b) When the student burned the fuel she saw soot in the funnel. Explain why soot forms. (2) Page 5 of 5
(c) The student burned another fuel which contained impurities. The substance in tube B is water containing universal indicator. The indicator turned red. Which gas made the indicator turn red? Tick one box. Ammonia Carbon monoxide Nitrogen Sulfur dioxide () (Total 4 marks) 3 (a) The hydrocarbon C 6 H 34 can be cracked. Balance the equation for cracking C 6 H 34 C 6 H 34 C 2 H 4 + C 8 H 8 () (b) Describe the differences between cracking and distillation. (2) Page 6 of 5
(c) What type of reaction is cracking? Tick one box. Combustion Decomposition Neutralisation Precipitation () Page 7 of 5
(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.5.7 Mass of solid waste in g 4 50 Mass of CO 2 produced in kg 0.23 0.53 Volume of fresh water used in dm 3 255 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. (6) (Total 0 marks) Page 8 of 5
4 There are several different forms of carbon and many different carbon compounds. (a) Figure shows a 3D model of a molecule of methane (CH 4 ). Figure Draw the 2D structure of a methane molecule. () (b) Different forms of carbon have different bonding and structure. Draw one line from the form of carbon to the bonding and structure. Form of carbon Bonding and structure (3) Page 9 of 5
(c) Crude oil is a mixture of many different carbon compounds. Crude oil can be separated into useful fractions by fractional distillation. Figure 2 shows a column used to separate crude oil. Figure 2 Complete the sentences. Use words from the box. condense evaporate freeze Crude oil is heated so that most of the compounds At different temperatures the compounds cool and (2) Page 0 of 5
(d) Which fraction is the most viscous? Tick one box. Engine oil Diesel oil Kerosene Petrol () (e) Which fraction is the most flammable? Tick one box. Diesel oil Kerosene Petrol Refinery gas () (f) Why does kerosene separate out of the mixture before diesel oil? () (Total 9 marks) Page of 5
5 A student investigated the viscosity of liquid hydrocarbons. A viscous liquid is a liquid that flows slowly. The student used this method. Measure 50 cm 3 of the liquid hydrocarbon. Pour the liquid hydrocarbon into the funnel, as shown in Figure. Time how long it takes for all of the liquid hydrocarbon to run out of the funnel. Repeat the experiment for other liquid hydrocarbons. (a) (i) Give the name of apparatus A in Figure. () Name the apparatus that could be used to measure 50 cm 3 of liquid hydrocarbon. () Page 2 of 5
(b) The student s results for six liquid hydrocarbons are shown in Table. Table Formula of liquid hydrocarbon Time for liquid hydrocarbon to run out of the funnel in seconds Experiment Experiment 2 Experiment 3 Mean time in seconds C 5 H 2 2 3 2 C 6 H 4 4 5 5 5 C 7 H 6 9 20 8 C 8 H 8 27 26 28 27 C 0 H 22 46 48 47 C 2 H 26 65 67 69 67 Page 3 of 5
(i) The student did the experiment three times with each liquid hydrocarbon. Give two reasons why. (2) Use the data in Table to calculate the mean time, in seconds, for C 7 H 6 Mean time = seconds () (iii) Complete the sentence. As the number of carbon atoms in a molecule of liquid hydrocarbon increases, the time taken for the liquid hydrocarbon to run out of the funnel. () (iv) A ring has been drawn around one result in Table. This result has not been used to calculate the mean time for C 0 H 22 Suggest why this result was not used. () (v) Suggest one error the student may have made to get the ringed result. () Page 4 of 5
(c) The student investigated the effect of temperature on the viscosity of one of the liquid hydrocarbons. The liquid hydrocarbon he was using had the hazard symbols shown in Figure 2. (i) Suggest why the student warmed the liquid hydrocarbon using warm water and not a Bunsen flame. () The student wore safety glasses. Give one other safety precaution the student should take, and give a reason for this safety precaution. Safety precaution Reason (2) (d) This is the method the student used to investigate the effect of temperature on the viscosity of one of the liquid hydrocarbons. Measure 50 cm 3 of the liquid hydrocarbon and pour it into a beaker. Stand the beaker of liquid hydrocarbon in a heated water bath. Leave for a few minutes. Measure the temperature of the liquid hydrocarbon. Pour the liquid hydrocarbon into the funnel, as shown in Figure 3. Page 5 of 5
Time how long it takes for all of the liquid hydrocarbon to run out of the funnel. Repeat the experiment at different temperatures. (i) The student s results are shown in Table 2. Table 2 Temperature of liquid hydrocarbon in C Time to run out of the funnel in seconds 23 27 30 2 37 7 46 6 55 65 9 Page 6 of 5
Plot the results shown in Table 2 on the graph in Figure 4. Draw a curve of best fit. (3) One of the points is anomalous. Draw a ring around the anomalous point on your graph. () (iii) Predict how long it will take the liquid hydrocarbon to run through the funnel at 70 C. Show your working on your graph. Time = seconds (2) (iv) Describe the relationship between the temperature of the liquid hydrocarbon and the viscosity of the liquid hydrocarbon. (3) (v) The apparatus the student used in Figure 2 could lead to a systematic error in the results. Identify one source of systematic error, and describe how the student could avoid or reduce the error. Page 7 of 5
(2) (Total 22 marks) 6 Methane (CH 4 ) is used as a fuel. (a) The displayed structure of methane is: Draw a ring around a part of the displayed structure that represents a covalent bond. () (b) Why is methane a compound? Tick ( ) one box. Methane contains atoms of two elements, combined chemically. Methane is not in the periodic table. Methane is a mixture of two different elements. () Page 8 of 5
(c) Methane burns in oxygen. (i) The diagram below shows the energy level diagram for the complete combustion of methane. Draw and label arrows on the diagram to show: the activation energy the enthalpy change, ΔH. (2) Complete and balance the symbol equation for the complete combustion of methane. CH 4 + CO 2 + (2) (iii) Explain why the incomplete combustion of methane is dangerous. (2) (iv) Explain why, in terms of the energy involved in bond breaking and bond making, the combustion of methane is exothermic. (3) Page 9 of 5
(d) Methane reacts with chlorine in the presence of sunlight. The equation for this reaction is: Some bond dissociation energies are given in the table. Bond Bond dissociation energy in kj per mole C H 43 C Cl 327 Cl Cl 243 H Cl 432 (i) Show that the enthalpy change, ΔH, for this reaction is 03 kj per mole. (3) Page 20 of 5
Methane also reacts with bromine in the presence of sunlight. This reaction is less exothermic than the reaction between methane and chlorine. The enthalpy change, ΔH, is 45 kj per mole. What is a possible reason for this? Tick ( ) one box. CH 3 Br has a lower boiling point than CH 3 Cl The C Br bond is weaker than the C Cl bond. The H Cl bond is weaker than the H Br bond. Chlorine is more reactive than bromine. () (Total 5 marks) 7 Crude oil is a fossil fuel. (a) To make crude oil more useful it is separated into fractions. Use the correct word from the box to complete each sentence. boiling compound decomposition distillation filtration mixture molecule (i) Crude oil is a of different substances. The substances in crude oil have different points. () () (iii) Crude oil is separated by fractional. () Page 2 of 5
(b) Petrol is one of the fractions produced from crude oil. Car engines use a mixture of petrol and air. The diagram shows some of the gases produced. (i) What type of reaction happens to petrol in a car engine? Tick ( ) one box. combustion decomposition neutralisation () Petrol contains octane (C 8 H 8 ). Complete the word equation for the reaction of octane with oxygen. octane + + (2) (iii) Cars use sulfur-free petrol as a fuel. Describe why sulfur should be removed from petrol. (2) Page 22 of 5
(c) Some fractions from crude oil contain large hydrocarbon molecules. These molecules can be cracked to produce smaller, more useful molecules. An equation for cracking decane is: C 0 H 22 C 3 H 8 + C 2 H 4 + C 5 H 0 decane propane ethene pentene (i) Why is propane useful? Tick ( ) one box. Propane is a polymer. Propane is an alloy. Propane is a fuel. () Draw bonds to complete the displayed structure of ethene. () (iii) What is the colour change when bromine water reacts with ethene? Tick ( ) one box. Orange to colourless Orange to green Orange to red () Page 23 of 5
(iv) Complete the sentence. Pentene is useful because many pentene molecules can join together to form. () (Total 2 marks) 8 The diagram shows a carbon atom. (a) (i) A proton is labelled. Use the correct answer from the box to label each of the other sub-atomic particles. electron ion molecule neutron (2) The atom of carbon is represented as: What is the mass number of this carbon atom? Draw a ring around the correct answer. 6 3 9 () (iii) Complete the sentence. Atoms of carbon have no overall electrical charge because the number of protons is the same as the number of. () Page 24 of 5
(b) Butane is represented as: (i) Use the correct answer from the box to complete each sentence. bond compound helium hydrogen mixture oxygen Butane is a. Butane contains atoms of carbon and. Each line between the atoms in butane represents a chemical. (3) Which is the correct formula for butane? Tick ( ) one box. C 4 H 4 C 4 H 8 C 4 H 0 () (Total 8 marks) 9 The diagrams represent two compounds, A and B. Compound A Compound B (a) (i) Compound B is an alcohol. Name compound B. () Page 25 of 5
Use the correct answer from the box to complete the sentence. burned decomposed oxidised To form compound A, compound B is () (iii) Compounds A and B are both colourless liquids. A test tube contains a colourless liquid, which could be either compound A or compound B. Describe a simple chemical test to show which compound, A or B, is in the test tube. (2) (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? () Compound C is an ester. Name compound C. () (iii) State one use of esters. () (Total 7 marks) Page 26 of 5
0 Sulfur is a non-metal. Sulfur burns in the air to produce sulfur dioxide, SO 2 (a) Why is it important that sulfur dioxide is not released into the atmosphere? Tick ( ) one box. Sulfur dioxide causes acid rain. Sulfur dioxide causes global dimming. Sulfur dioxide causes global warming. () (b) Sulfur dioxide dissolves in water. What colour is universal indicator in a solution of sulfur dioxide? Give a reason for your answer. (2) (c) Sulfur dioxide is a gas at room temperature. The bonding in sulfur dioxide is covalent. Explain, in terms of its structure and bonding, why sulfur dioxide has a low boiling point. (3) Page 27 of 5
(d) In this question you will be assessed on using good English, organising information clearly and using specialist terms where appropriate. Sulfur dioxide is produced when fossil fuels are burned. It is important that sulfur dioxide is not released into the atmosphere. Three of the methods used to remove sulfur dioxide from gases produced when fossil fuels are burned are: wet gas desulfurisation ( W) dry gas desulfurisation ( D) seawater gas desulfurisation ( S). Information about the three methods is given in the bar chart and in Table and Table 2. Method of removing sulfur dioxide Table Method Material used How material is obtained W Calcium carbonate, CaCO 3 Quarrying D Calcium oxide, CaO Thermal decomposition of calcium carbonate: CaCO 3 CaO + CO 2 S Seawater From the sea Table 2 Method W D S What is done with waste material Solid waste is sold for use in buildings. Carbon dioxide is released into the atmosphere. Solid waste is sent to landfill. Liquid waste is returned to the sea. Page 28 of 5
Evaluate the three methods of removing sulfur dioxide from waste gases. Compare the three methods and give a justified conclusion. (6) (Total 2 marks) 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. () Page 29 of 5
Complete the word equation for the oxidation of hydrogen. hydrogen + oxygen () (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? (4) (Total 6 marks) 2 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. (3) Page 30 of 5
(b) Diesel is a mixture of lots of different alkanes. What are alkanes? (2) (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. Page 3 of 5
Canada s oil sands hold about 20% of the world s known crude oil reserves. The oil sands contain between 0 to 5% 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. (6) (Total marks) Page 32 of 5
3 Energy is released by burning fuels. (a) The bar chart shows the energy in kilojoules, kj, released by burning g of five different fuels. (i) Which fuel releases least energy by burning g? () How much energy is released by burning g of coal? Energy = kj () (iii) Calculate the mass of petrol that will release the same amount of energy as g of hydrogen. Use information from the bar chart to help you. Mass = g () Page 33 of 5
(b) Coal burns in oxygen and produces the gases shown in the table. Name Formula Carbon dioxide CO 2 Water vapour H 2 O Sulfur dioxide SO 2 Use information from the table to name one element that is in coal. () (c) Hydrogen can be made from fossil fuels. Hydrogen burns rapidly in oxygen to produce water only. A lighthouse uses electricity generated by burning hydrogen. Suggest two advantages of using hydrogen as a fuel. Use information from the bar chart and the diagram above to help you.. 2. (2) (Total 6 marks) Page 34 of 5
4 Scientists study the atmosphere on planets and moons in the Solar System to understand how the Earth s atmosphere has changed. (a) Millions of years ago the Earth s atmosphere was probably just like that of Mars today. The table shows data about the atmosphere of Mars and Earth today. Mars today Earth today nitrogen 3% nitrogen 78% oxygen trace oxygen 2% water trace water trace Carbon dioxide 95% Carbon dioxide trace Average surface temperature 23 C Average surface temperature 5 C The percentages of some gases in the Earth s atmosphere of millions of years ago have changed to the percentages in the Earth s atmosphere today. For two of these gases describe how the percentages have changed and suggest what caused this change. (2) Page 35 of 5
(b) Titan is the largest moon of the planet Saturn. Titan has an atmosphere that contains mainly nitrogen. Methane is the other main gas. Main gases in Titan's atmosphere Percentage (%) Boiling point in C Nitrogen 95 96 Methane 5 64 Average surface temperature 78 C When it rains on Titan, it rains methane! Use the information above and your knowledge and understanding to explain why. (2) (c) Ultraviolet radiation from the Sun produces simple alkenes, such as ethene (C 2 H 4 ) and propene (C 3 H 6 ) from methane in Titan s atmosphere. State the general formula for alkenes. () (Total 5 marks) 5 Alkanes are hydrocarbons found in crude oil. (a) (i) Complete the sentence. Hydrocarbons contain the elements and only. () Page 36 of 5
Ethane is an alkane with the formula C 2 H 6 Draw a ring around the correct answer to complete the sentence. C n H n Alkanes are hydrocarbons with the general formula C n H 2n C n H 2n+2 () (b) Crude oil is separated into useful fractions by fractional distillation. Describe and explain how crude oil is separated into fractions by fractional distillation. Use the diagram to help you answer the question. (4) (c) Dodecane (C 2 H 26 ) from crude oil is cracked to produce ethene (C 2 H 4 ). (i) Complete the equation for this reaction. C 2 H 26 2 C 2 H 4 + () Page 37 of 5
Give two conditions needed for cracking.. 2. (2) (Total 9 marks) 6 Saturated hydrocarbons, for example methane and octane, are often used as fuels. (a) Methane can be represented as: (i) The formula of methane is. () Draw a ring around the correct answer to complete the sentence. double. In a saturated hydrocarbon molecule all of the bonds are ionic. single. () (iii) Draw a ring around the correct answer to complete the sentence. alcohols. The homologous series that contains methane and octane is called the alkanes. alkenes. () (b) (i) The complete combustion of petrol produces carbon dioxide, water vapour and sulfur dioxide. Name three elements petrol must contain.. 2. 3. (3) The exhaust gases from cars can contain oxides of nitrogen. Complete the sentence. Nitrogen in the oxides of nitrogen comes from. () Page 38 of 5
(iii) The sulfur dioxide and oxides of nitrogen from cars cause an environmental problem. Name the problem and describe one effect of the problem. Name of problem Effect of problem (2) (c) When a fuel burns without enough oxygen, there is incomplete combustion. One gaseous product of incomplete combustion is carbon monoxide. Name one solid product of incomplete combustion. () (d) A student investigated how well different hydrocarbon fuels would heat up 00 g of water. Her hypothesis was: The more carbon atoms there are in a molecule of any fuel, the better the fuel is. The apparatus the student used is shown in the diagram. Page 39 of 5
She burned each hydrocarbon fuel for 2 minutes. Her results are shown in the table. Name of hydrocarbon fuel Number of carbon atoms in a molecule of hydrocarbon fuel Temperature change of water in C after 2 minutes Temperature change per g of fuel burned Observations Pentane 5 30 60 no smoke Hexane 6 40 57 very small amount of smoke Octane 8 55 55 small amount of smoke Decane 0 57 52 large amount of smoke Dodecane 2 60 43 very large amount of smoke The student investigated only hydrocarbons. Look carefully at her results. How well do the student s results support her hypothesis? The more carbon atoms there are in a molecule of any fuel, the better the fuel is. Give reasons for your answer. (4) Page 40 of 5
(e) A 0.050 mol sample of a hydrocarbon was burned in excess oxygen. The products were 3.60 g of water and 6.60 g of carbon dioxide. (i) Calculate the number of moles of carbon dioxide produced. Relative atomic masses: C = 2; O = 6. Moles of carbon dioxide = (2) When the hydrocarbon was burned 0.20 mol of water were produced. How many moles of hydrogen atoms are there in 0.20 mol of water? Moles of hydrogen atoms = () (iii) The amount of hydrocarbon burned was 0.050 mol. Use this information and your answers to parts (e) (i) and (e) to calculate the molecular formula of the hydrocarbon. If you could not answer parts (e) (i) or (e) use the values of 0.20 moles carbon dioxide and 0.50 moles hydrogen. These are not the answers to parts (e) (i) and (e). Formula = (2) (Total 9 marks) Page 4 of 5
7 Barbecues are heated by burning charcoal or burning hydrocarbons. (a) Use the Chemistry Data Sheet to help you to answer this question. The chemical equation for charcoal burning is: C + O 2 CO 2 Complete the word equation for this reaction. carbon + carbon dioxide () (b) Propane is a hydrocarbon. (i) Complete the displayed structure of propane. Draw in the missing bonds. Write the chemical formula of propane. () () Page 42 of 5
(iii) Draw a ring around the correct answer to complete the sentence. hydrogen. Propane burns in air to produce carbon dioxide and hydroxide. water. () (c) The table shows information about six hydrocarbons. Hydrocarbon State at room temperature (20 C) Boiling point in C Ethane (C 2 H 6 ) gas 89 Ethene (C 2 H 4 ) gas 04 Butane (C 4 H 0 ) gas Butene (C 4 H 8 ) gas 6 Hexane (C 6 H 4 ) liquid +69 Hexene (C 6 H 2 ) liquid +64 Tick ( ) two correct statements about the six hydrocarbons. Statement Tick ( ) Ethane and butane boil at temperatures less than 20 C. Hexene and butene are alkanes. Butane and hexane are liquid at 0 C. Ethene and hexene each have a carbon-carbon double bond. (2) (Total 6 marks) 8 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. () Page 43 of 5
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. (2) (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. Page 44 of 5
9 (a) Use the diagram and your knowledge to answer this question. Crude oil is a mixture of compounds. These compounds are made up of hydrogen and carbon atoms only. (6) (Total 9 marks) (i) Draw a ring around the correct answer to complete the sentence. alcohols. Compounds made up of carbon and hydrogen atoms only are called hydrocarbons. vegetable oils. () The table shows five of these compounds. Compound State at room temperature (20 C) Boiling point in C ethane, C 2 H 6 gas 89 butane, C 4 H 0 gas 0 hexane, C 6 H 4 liquid +69 pentadecane, C 5 H 32 liquid +270 heptadecane, C 7 H 36 solid +302 Page 45 of 5
Tick ( ) two correct statements about the five compounds. Statement Tick ( ) ethane has the smallest molecules hexane and pentadecane are liquid at 00 C heptadecane has the highest boiling point butane boils at 00 C (2) (iii) Draw a ring around the correct answer to complete each sentence. Fractional distillation is used to separate the compounds in crude oil. cracking The first step in fractional distillation is displacing the crude oil. evaporating burn During fractional distillation the compounds condense at different temperatures. decompose (2) Page 46 of 5
(b) Steam distillation is used to separate oils from plants. The diagram shows some apparatus that can be used to separate oil from lavender plants. Four parts of the apparatus are labelled W, X, Y and Z. (i) In which part, W, X, Y or Z, of the apparatus: is steam produced are steam and oil condensed? (2) Use the correct word from the box to complete the sentence. dissolves floats sinks When the oil separates from the water, the oil () (iii) Describe how part Z of the apparatus can be used to remove the water from the oil. (2) (Total 0 marks) Page 47 of 5
20 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 C 6 H 4 nitrogen 78 heptane oxygen 2 octane C 8 H 8 carbon dioxide 0.035 nonane C 9 H 20 decane C 0 H 22 Small amounts of other gases and water vapour (a) Use the information above to answer these questions. (i) Give the formula for heptane () Complete the general formula of alkanes. n = number of carbon atoms C n H () (b) Alkanes in petrol burn in air. The equations represent two reactions of hexane burning in air. Reaction 2C 6 H 4 + 9O 2 2CO 2 + 4H 2 O Reaction 2 2C 6 H 4 + 3O 2 2CO + 4H 2 O Reaction 2 produces a different carbon compound to Reaction. (i) Name the carbon compound produced in Reaction 2. () Give a reason why the carbon compounds produced are different. () Page 48 of 5
(c) The table shows the percentages of some gases in the exhaust from a petrol engine. Name of gas Percentage (%) nitrogen 68 carbon dioxide 5 carbon monoxide.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? () What is the name of the compound that makes up most of the other gases? () (iii) Give a reason why sulfur dioxide is produced in a petrol engine. () (iv) State how nitrogen oxides are produced in a petrol engine. (2) Page 49 of 5
(d) Many scientists are concerned about the carbon dioxide released from burning fossil fuels such as petrol. Explain why. (2) (Total marks) Page 50 of 5
2 About 3000 million years ago carbon dioxide was one of the main gases in the Earth s early 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. Today coal is burned in power stations to release the energy needed by industry. (a) The bar chart shows the percentage of some of the elements in this coal. (i) This coal contains 85 % carbon. Draw the bar for carbon on the chart. () Page 5 of 5
Coal is burned in the atmosphere to release energy. Two of the products of burning coal are shown. Draw one line from each product to its environmental impact. Product Environmental impact Acid rain Sulfur dioxide Global dimming Carbon particles Global warming (2) (b) Use the information above and your knowledge and understanding to answer these questions. (i) How did the formation of coal decrease the amount of carbon dioxide in the Earth s early atmosphere? () How does burning coal affect the amount of carbon dioxide in the Earth s atmosphere? Explain your answer. (2) (Total 6 marks) Page 52 of 5
22 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. (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. (2) Page 53 of 5
Explain why clearing large areas of forest has an environmental impact on the atmosphere. (2) (b) Why is there an increasing demand for biodiesel? () (c) Suggest why producing biodiesel from crops: (i) causes ethical concerns () causes economic concerns. () (Total 7 marks) Page 54 of 5
23 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. (3) (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. (2) (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. 2CaCO 3 (s) + 2SO 2 (g) + O 2 (g) CaSO 4 (s) + CO 2 (g) () Page 55 of 5
Explain how the use of calcium carbonate in the mixture: increases atmospheric pollution decreases atmospheric pollution. (4) (Total 0 marks) 24 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. () Page 56 of 5
What conclusions can the scientist make about the viscosity of biodiesel compared with the viscosity of petroleum diesel at different temperatures? (2) (iii) Biodiesel may be less suitable than petroleum diesel as a fuel for cars. Use these results to suggest one reason why. () Page 57 of 5
(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. Nitrogen oxides and sulfur dioxide cause a similar environmental impact. (i) What environmental impact do particulates from car exhaust systems cause? () What is the percentage reduction in particulates when using B00 instead of petroleum diesel? % () Page 58 of 5
(iii) Replacing petroleum diesel with biodiesel increases one type of environmental pollution. Use the bar chart and the information given to explain why. (2) (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. (2) (Total 0 marks) Page 59 of 5
25 Read the article and then answer the questions. Supermarkets launch eco-friendly plastic milk bags. Could this be the end of the milk bottle? Milk bottles are made from glass or from plastic. Glass milk bottles contain 0.5 litres of milk. When the milk is used up the empty bottles are returned to be re-used. Glass milk bottles are re-used 24 times on average. The glass to make new milk bottles is produced when a mixture of sand, limestone, soda and recycled glass is heated to about 600 C in a furnace. There are almost unlimited amounts of the raw materials needed to produce this glass. About 35% of used glass is recycled. The most common plastic milk bottles contain 2 litres of milk. When the milk is used up the empty bottles are discarded as waste. The plastic used to make these milk bottles is poly(ethene). Poly(ethene) is produced from crude oil by first using fractional distillation, then cracking the naphtha fraction and finally polymerising the ethene. About 5% of used poly(ethene) is recycled. The new plastic milk bags contain 2 litres of milk. The milk bags are also made from poly(ethene). A milk bag uses 75% less poly(ethene) than is used to make the poly(ethene) milk bottles. When the milk is used up the empty bags are discarded as waste. (a) Describe what happens in fractional distillation so that fractions, such as naphtha, are separated from crude oil. (3) Page 60 of 5
(b) Supermarkets claim that using milk bags instead of milk bottles would have less environmental impact. Do you agree with this claim? Use the information in the article and your knowledge and understanding to make appropriate comparisons to justify your answer. (4) (Total 7 marks) Page 6 of 5
26 Crude oil is used to produce many useful materials. (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. (3) Page 62 of 5
(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 atoms found in the molecules Gasoline (petrol) 20-200 5-0 Kerosene (paraffin) 80-260 0-6 Diesel 260-340 4-20 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? () How does the number of carbon atoms in a molecule affect its boiling point? () (c) Fuels are substances that release energy. (i) Name the reaction that releases energy from a fuel such as gasoline (petrol). () Describe how fuel oil is broken down into smaller, more useful molecules such as gasoline (petrol). (2) (Total 8 marks) Page 63 of 5
27 Supermarkets in the UK have been advised by the Government to stop giving plastic bags to customers. The Government states that this is because plastic bags use up resources that are not renewable and that the manufacture of plastic bags produces carbon dioxide. Most of these plastic bags are made from poly(ethene). The table shows methods to deal with large numbers of used plastic bags. Method Reused Recycled Burned Dumped Description of what happens to the plastic bag used again by the customer collected, transported, washed and melted to make new plastic items collected, transported and burnt to release heat energy mixed with other household waste, collected, transported and disposed of at a landfill site Use the information and your knowledge and understanding to briefly give one advantage and one disadvantage for each of these methods. Reused Recycled Burned Dumped (4) (Total 4 marks) Page 64 of 5
28 This information about diesel was printed in a magazine. Almost all of the crops that we eat can be converted into fuel for cars. Vegetable oils can be used as biodiesel. Diesel from crude oil is called fossil diesel. When either biodiesel or fossil diesel burn they both produce similar amounts of carbon dioxide. Both types of diesel produce carbon monoxide. However, biodiesel produces fewer carbon particles and less sulfur dioxide. (a) Carbon monoxide can be produced when diesel burns in a car engine. Explain how. (2) (b) Use the information at the start of this question and your knowledge and understanding to evaluate the use of biodiesel compared with fossil diesel as a fuel for cars. Remember to give a conclusion to your evaluation. (5) (Total 7 marks) Page 65 of 5
29 In the future: there will be fewer oil burning power stations there may be more wood burning power stations. (a) Which one of the emissions from the chimney can cause acid rain? () (b) Draw a ring around the correct answer to complete the sentence. acid rain. Carbon particles in the Earth s atmosphere cause global dimming. global warming. () (c) Which gas in the air is needed for oil or wood to burn? () (d) Suggest why there will be fewer power stations burning oil in the future. () Page 66 of 5
(e) Some power stations burn wood. The wood comes from trees grown in forests. Suggest why burning wood in power stations is said to be carbon-neutral. (2) (Total 6 marks) 30 Crude oil is a mixture of hydrocarbons. Crude oil can be separated into fractions. (a) (i) Complete the sentence. The process used to separate the crude oil into fractions is called fractional. () Why do the fractions separate at different temperatures? () Page 67 of 5
(b) Tick ( ) two properties of fraction 6. Property Tick ( ) contains hydrocarbons has a small number of carbon atoms in each molecule is easy to ignite has a high boiling point (2) (c) Fraction contains hydrocarbons called alkanes. The general formula of an alkane is: C n H 2n+2 What is the formula of the alkane that has 5 carbon atoms in each molecule? Draw a ring around the correct answer. C 5 H 9 C 5 H 0 C 5 H C 5 H 2 () (Total 5 marks) 3 Crude oil is a mixture of hydrocarbons. Most of these hydrocarbons are alkanes. (a) The general formula of an alkane is C n H 2n+2 Complete the structural formula for the alkane that has six carbon atoms in its molecules. () Page 68 of 5
(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. () Suggest two reasons why all of the alkanes in the bar chart are better fuels than the alkane with the formula C 30 H 62. 2. (2) Page 69 of 5
(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 00 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 C 8 H 8 + 25 O 2 CO 2 + H 2 O () Where did the carbon that is locked up in fossil fuels come from? () (iii) The burning of fossil fuels has caused the percentage of carbon dioxide in the atmosphere to increase to above 0.03 %. Explain why. (2) (Total 8 marks) Page 70 of 5
32 Petroleum diesel is produced from crude oil. Most vehicles that use petroleum diesel as fuel can also use biodiesel or a mixture of these two fuels. In the UK (in 200) there must be 5 % biodiesel in all petroleum diesel fuel. Biodiesel is produced from plant oils such as soya. The crops used to produce biodiesel can also be used to feed humans. The benefit that biodiesel is carbon neutral is outweighed by the increasing demand for crops. This increasing demand is causing forests to be burnt to provide land for crops to produce biodiesel. Only a huge fall in the price of petroleum diesel would halt the increasing use of biodiesel. The graph shows the average percentage change in exhaust emissions from vehicles using different mixtures of petroleum diesel and biodiesel. There is no difference in carbon dioxide emissions for all mixtures of petroleum diesel and biodiesel. Use the information and your knowledge and understanding to evaluate the use of plant oils to produce biodiesel. Remember to give a conclusion to your evaluation. Page 7 of 5
(5) (Total 5 marks) 33 Natural gas is mainly a hydrocarbon called methane. (a) Use one word from the box to complete the sentence. compounds elements molecules Hydrocarbons contain hydrogen and carbon only. Hydrogen and carbon are. () (b) The diagrams represent atoms of hydrogen and carbon. Draw a ring around the correct answer to complete the sentences. bond. (i) The centre of each atom is called the nucleus. symbol. () Page 72 of 5
three The hydrogen atom has one electron and the carbon atom has four electrons. six () (c) A molecule of methane can be represented as Draw a ring around the correct answer to complete the sentences. CH (i) The formula of methane is CH 4 C 4 H 4 () bond. The line between C H is called a molecule. nucleus. () (d) Methane burns to produce carbon dioxide (CO 2 ) and water (H 2 O). (i) Draw a ring around the correct answer to complete the sentence. carbon. When methane burns it reacts with nitrogen. oxygen. () Hydrogen (H 2 ) can be used as a fuel. Suggest why burning hydrogen would be less harmful to the environment than burning methane. () (Total 7 marks) Page 73 of 5
34 In the future more coal-fired and fewer oil-fired power stations will be used to generate electricity. When coal and oil are burned they produce the same types of emissions which can cause environmental problems. (a) Emissions from the chimney can cause acid rain, global dimming and global warming. Draw one straight line from each possible environmental problem to the emission that causes it. Possible environmental problem Emission that causes it carbon particles acid rain carbon dioxide global warming sulfur dioxide global dimming water vapour (3) (b) Draw a ring around the correct word in the box to complete each sentence. carbon dioxide. (i) Incomplete combustion of coal or oil is caused by too little nitrogen. oxygen. () Page 74 of 5
carbon monoxide. A gas formed by the incomplete combustion of coal or oil is hydrogen. oxygen. () (c) The table shows the world production for both coal and oil in 2000. The world production figures after 2000 are predicted. Year World production of coal (billions of tonnes per year) World production of oil (billions of barrels per year) 2000 3.5 2.5 2050 4.5 5.6 200 5.0.7 250 5.5 0.5 2200 6.0 0.0 (i) How is the world production of oil predicted to change from 2000 to 2200? () Suggest two reasons why the world production of coal is predicted to increase.. 2. (2) (Total 8 marks) Page 75 of 5
35 (a) Alkanes are important hydrocarbon fuels. They have the general formula C n H 2n+2 The points on the graph show the amount of energy released when mole of methane (CH 4 ), ethane (C 2 H 6 ), propane (C 3 H 8 ) and butane (C 4 H 0 ) are burned separately. (i) (iii) Draw a line through the points and extend your line to the right-hand edge of the graph. Use the graph to estimate the amount of energy released when mole of octane (C 8 H 8 ) is burned. Energy released = kj Suggest why we can make a good estimate for the energy released by mole of pentane (C 5 H 2 ). () () () Page 76 of 5
(iv) A student noticed that octane (C 8 H 8 ) has twice as many carbon atoms as butane (C 4 H 0 ), and made the following prediction: When burned, mole of octane releases twice as much energy as mole of butane. Use the graph to decide if the student s prediction is correct. You must show your working to gain credit. (2) (b) Some information about four fuels is given in the table. Combustion products Fuel Type Heat released in kj per g CO 2 SO 2 H 2 O Type of flame Bio-ethanol Renewable 29 Not smoky Coal Non-renewable 3 Smoky Hydrogen Renewable 42 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. (2) Page 77 of 5
Non-renewable fuels are better for the environment than renewable fuels. (2) (Total 9 marks) Page 78 of 5
Mark schemes (a) Flask (b) Fractional distillation (c) A boiling in this order (d) (e) (f) B condensing Pentane Formulation the fuel is a pure compound and crude oil is a mixture or the fuel is made up of four hydrocarbons allow crude oil contains a large number of compounds and the fuel contains four and crude oil could have many more (g) (35 + 37 + 37 / 3) = 36.33 36 allow (35 + 48 + 37 + 37 / 4 =) 39(.25) for mark [0] 2 (a) Colourless liquid / condensation / water (b) incomplete combustion of the fuel because not enough oxygen (c) Sulfur dioxide [4] 3 (a) 4 (C 2 H 4 ) Page 79 of 5
(b) (c) (d) cracking involves a catalyst distillation does not or distillation does not involve a chemical change but cracking does Decomposition Level 3 (5 6 marks): A logically structured evaluation with links involving several comparisons. Nearly all points made are relevant and correct. Level 2 (3 4 marks): Some valid comparisons made between the two types of bag. There may be some incorrect or irrelevant points. Level ( 2 marks): A vague response with few correct and relevant points and with no direct comparisons. 0 marks: No relevant content Indicative content Accept converse in terms of plastic bags for all statements Paper bags are made from a renewable resource Plastic bags are made from a finite resource Paper bags require more energy to manufacture Paper bags produce more waste Paper bags are biodegradable Paper bags create more CO 2 CO 2 created by paper bags offset by photosynthesis in growing wood Paper bag requires much more fresh water Paper bags cannot be recycled Agree because non-renewability less important than other factors or disagree because of converse or can t say because data inconclusive / incomplete 6 [0] 4 (a) Page 80 of 5
(b) Form of carbon Bonding and structure extra lines from the left negate the mark 3 (c) evaporate condense (d) Engine oil (e) Refinery gas (f) because its boiling point is lower [9] 5 (a) (i) (conical) flask measuring cylinder / pipette / burette Page 8 of 5
(b) (i) any two from: so anomalous results could be identified / ignored so a mean / average could be taken (to improve) accuracy 9 2 (iii) increases / gets longer / gets bigger (iv) anomalous / does not agree with other times for C 0 H 22 (v) any one from: shorter hydrocarbon used volume of hydrocarbon too small started timing late stopped timing too early / when liquid left in funnel must suggest why the result is lower than the others. allow the temperature was higher or the students used a wider funnel. (c) (i) flammable suitable safety precaution reason that links the safety precaution to the hazard symbols eg: wear gloves (because) it is hazardous to health / harmful / toxic / irritant or do not pour down sink or dispose of properly (because) it is harmful to the environment / kills fish or wear a mask or do it in the fume cupboard or a well-ventilated area respiratory irritant Page 82 of 5
(d) (i) points plotted correctly (within half small square) all six points correct scores 2 3, 4 or 5 points correct scores smooth curve of best fit 2 (iii) (iv) (v) point at 46 C circled allow point furthest from the line as drawn working shown on graph value read from graph line drawn (within half small square) the higher the temperature the lower the viscosity allow the higher the temperature the lower / shorter the time taken for mark non-linear or change gets smaller as temperature gets higher answer relating temperature to time taken can score a maximum of 2 marks. identifying source of the error 2 method of avoiding the error eg: the temperature will drop insulate the funnel or runs out before all added put a tap on the funnel [22] 6 (a) circle round any one (or more) of the covalent bonds any correct indication of the bond the line between letters (b) Methane contains atoms of two elements, combined chemically Page 83 of 5
(c) (i) activation energy labelled from level of reagents to highest point of curve ignore arrowheads enthalpy change labelled from reagents to products arrowhead must go from reagents to products only 2 O 2 (iii) (iv) 2 H 2 O if not fully correct, award mark for all formulae correct. ignore state symbols carbon monoxide is made this combines with the blood / haemoglobin or prevents oxygen being carried in the blood / round body or kills you or is toxic or poisonous dependent on first marking point energy is taken in / required to break bonds accept bond breaking is endothermic energy is given out when bonds are made accept bond making is exothermic the energy given out is greater than the energy taken in this mark only awarded if both of previous marks awarded Page 84 of 5
(d) (i) energy to break bonds = 895 calculation with no explanation max = 2 energy from making bonds = 998 895 998 (= 03) or energy to break bonds = 656 energy from making bonds = 759 656 759 (= 03) allow: bonds broken bonds made = 43 + 243 327 432 = -03 for 3 marks. The C Br bond is weaker than the C Cl bond [5] 7 (a) (i) mixture (of different substances) (iii) boiling (points) distillation (b) (i) combustion (reactant) oxygen allow correct formulae (products) products in any order carbon dioxide allow carbon or carbon monoxide and water allow water vapour or steam or hydrogen oxide (iii) (burning sulfur) produces sulfur dioxide / S0 2 allow it / sulfur reacts with oxygen ignore sulfur oxide causes acid rain Page 85 of 5