An etching can be made when a sheet of brass reacts with iron chloride solution. (i) A mixture of two metals is called... (1)

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1 Q. Printed pictures can be made using etchings. Eduardo Jose Bernardino/iStock An etching can be made when a sheet of brass reacts with iron chloride solution. (a) Brass is a mixture of two metals, copper and zinc. (i) A mixture of two metals is called.... () (ii) Draw a ring around the correct answer to complete the sentence. Copper and zinc atoms are different sizes. harder This makes brass more flexible than the pure metals. softer () (b) Iron chloride has the formula FeCl 3 Relative atomic masses (A r ): Cl = 35.5; Fe = 56. (i) Calculate the relative formula mass (M r ) of iron chloride (FeCl 3 ). Relative formula mass (M r ) of iron chloride =... () Page of 36

2 (ii) Calculate the percentage of iron in iron chloride (FeCl 3 ). Percentage of iron in iron chloride =...% () (Total 6 marks) Q. Some students investigated magnesium oxide. (a) Magnesium oxide has the formula MgO. (i) Calculate the relative formula mass (M r ) of magnesium oxide. Relative atomic masses: O = 6; Mg = 4. Relative formula mass =... () (ii) Calculate the percentage by mass of magnesium in magnesium oxide. Percentage by mass of magnesium in magnesium oxide =...% () (iii) Calculate the mass of magnesium needed to make 5 g of magnesium oxide. Mass of magnesium =... g () Page of 36

3 (b) The students calculated that if they used 0. g of magnesium they should make 0.0 g of magnesium oxide. They did this experiment to find out if this was correct. The students weighed 0. g of magnesium ribbon into a crucible. They heated the magnesium ribbon. They lifted the lid of the crucible slightly from time to time to allow air into the crucible. The students tried to avoid lifting the lid too much in case some of the magnesium oxide escaped. When all of the magnesium appeared to have reacted, the students weighed the magnesium oxide produced. The results of the experiment are shown below. Mass of magnesium used in grams Mass of magnesium oxide produced in grams (i) The mass of magnesium oxide produced was lower than the students had calculated. They thought that this was caused by experimental error. Suggest two experimental errors that the students had made. () Page 3 of 36

4 (ii) The students only did the experiment once. Give two reasons why they should have repeated the experiment. () (Total 9 marks) Q3. Perfumes contain a mixture of chemicals. The main ingredients of perfumes are a solvent and a mixture of fragrances. Page 4 of 36

5 (a) A sample of the solvent used in one perfume contained 0.60 g of carbon, 0.5 g of hydrogen and 0.40 g of oxygen. Relative atomic masses: H = l; C = ; O = 6. Calculate the empirical (simplest) formula of the solvent. You must show all of your working to gain full marks for this question (4) (b) Solvent molecules evaporate easily. Explain why substances made of simple molecules evaporate easily () (c) Most companies claim that their perfumes have been tested on skin. A study was made of the tests they used. The study found that each company used different tests. The perfumes were tested in the companies own laboratories and not by independent scientists. Some companies did not give any information about the tests that they had used. (i) Suggest why companies test their perfumes on skin () Page 5 of 36

6 (ii) Did the study show that the tests made by the different companies were valid and reliable? Explain your answer () (Total 9 marks) Page 6 of 36

7 Q4. The picture shows a painting which was painted in a cave in France about years ago. By Carla Hufstedler [CC-BY-SA-.0], via Wikimedia Commons One of the pigments in this painting contains: 70 % of iron (Fe) and 30 % of oxygen (O) Calculate the simplest (empirical) formula of this substance. Relative atomic masses: O = 6; Fe = (4) (Total 4 marks) Page 7 of 36

8 Q5. Aspirin tablets have important medical uses. A student carried out an experiment to make aspirin. The method is given below.. Weigh.00 g of salicylic acid.. Add 4 cm 3 of ethanoic anhydride (an excess). 3. Add 5 drops of concentrated sulfuric acid. 4. Warm the mixture for 5 minutes. 5. Add ice cold water to remove the excess ethanoic anhydride. 6. Cool the mixture until a precipitate of aspirin is formed. 7. Collect the precipitate and wash it with cold water. 8. The precipitate of aspirin is dried and weighed. (a) The equation for this reaction is shown below. C 7 H 6 O 3 + C 4 H 6 O 3 C 9 H 8 O 4 + CH 3 COOH salicylic acid aspirin Calculate the maximum mass of aspirin that could be made from.00 g of salicylic acid. The relative formula mass (M r ) of salicylic acid, C 7 H 6 O 3, is 38 The relative formula mass (M r ) of aspirin, C 9 H 8 O 4, is Maximum mass of aspirin =... g () Page 8 of 36

9 (b) The student made.0 g of aspirin from.00 g of salicylic acid. Calculate the percentage yield of aspirin for this experiment. (If you did not answer part (a), assume that the maximum mass of aspirin that can be made from.00 g of salicylic acid is.50 g. This is not the correct answer to part (a).) Percentage yield of aspirin =... % () (c) Suggest one possible reason why this method does not give the maximum amount of aspirin () (d) Concentrated sulfuric acid is a catalyst in this reaction. Suggest how the use of a catalyst might reduce costs in the industrial production of aspirin () (Total 6 marks) Q6. Petrol is a mixture of hydrocarbons such as octane, C 8 H 8 When petrol is burned in a car engine, a large amount of carbon dioxide is produced. This car uses 4 g of petrol to travel one mile. Calculate the mass of carbon dioxide produced when this car travels one mile. Assume that petrol is octane and that combustion is complete. (Relative atomic masses: H = ; C = ; O = 6) Page 9 of 36

10 The combustion of octane can be represented by this equation. C 8 H 8 + O 8CO + 9H O Mass of carbon dioxide =... g (Total 3 marks) Q7. Ethene can be identified using instrumental methods. (i) Name one instrumental method used to identify elements or compounds () (ii) Give one advantage of using instrumental methods compared with chemical tests () (Total marks) Page 0 of 36

11 Q8. The diagram shows the main parts of an instrumental method called gas chromatography linked to mass spectroscopy (GC-MS). This method separates a mixture of compounds and then helps to identify each of the compounds in the mixture. (a) In which part of the apparatus: (i) is the mixture separated?... () (ii) is the relative molecular mass of each of the compounds in the mixture measured? () (b) (i) Athletes sometimes take drugs because the drugs improve their performance. One of these drugs is ephedrine. Ephedrine has the formula: C 0 H 5 NO What relative molecular mass (M r ) would be recorded by GC-MS if ephedrine was present in a blood sample taken from an athlete? Show clearly how you work out your answer. Relative atomic masses: H = ; C = ; N = 4; O = 6. Relative molecular mass =... () Page of 36

12 (ii) Another drug is amphetamine which has the formula: C 9 H 3 N The relative molecular mass (M r ) of amphetamine is 35. Calculate the percentage by mass of nitrogen in amphetamine. Relative atomic mass: N = 4 Percentage of nitrogen =... % () (c) Athletes are regularly tested for drugs at international athletics events. An instrumental method such as GC-MS is better than methods such as titration. Suggest two reasons why () (d) When a blood sample is taken from an athlete the sample is often split into two portions. Each portion is tested at a different laboratory. Suggest why () (Total 0 marks) Page of 36

13 Q9. (a) The formula for the chemical compound magnesium sulphate is MgSO 4. Calculate the relative formula mass (M r )of this compound. (Show your working.) () (b) Magnesium sulphate can be made from magnesium and dilute sulphuric acid. This is the equation for the reaction. Mg + H SO 4 MgSO 4 + H Calculate the mass of magnesium sulphate that would be obtained from 4g of magnesium. (Show your working.) Answer... g () (Total 4 marks) ## In this question you will need to use the following information: Relative atomic masses: H ; O 6; Mg 4. The volume of one mole of any gas is 4 dm 3 at room temperature and atmospheric pressure. Page 3 of 36

14 The diagram shows a chemical reaction taking place in a conical flask. The balanced equation for this reaction is: Mg(s) + HCl(aq) MgCl (aq) + H (g) (a) Write a balanced ionic equation for this reaction.... () (b) Calculate the mass of magnesium required to produce 0.50 g of hydrogen. Show clearly how you work out your final answer and give the unit Mass =... () (c) (i) Draw a diagram to show how the electrons are arranged in a hydrogen molecule. () (ii) What is the name of the type of chemical bond between the hydrogen atoms in a hydrogen molecule?... () Page 4 of 36

15 (d) The chemical formula for hydrogen peroxide is H O. Calculate, to the nearest whole number, the percentage, by mass, of hydrogen in hydrogen peroxide. Show clearly how you work out your answer Percentage =... % () (Total 8 marks) Q. Thermosoftening polymers can be used to make plastic bottles and food packaging. (a) The reaction to produce polymers uses a catalyst. Why does the catalyst work for a long time before it needs replacing? () (b) Thermosoftening polymers would not be suitable for packaging very hot food. Explain why in terms of their properties and structure () Page 5 of 36

16 (c) Compounds from food packaging must not contaminate the food. Food can be tested for contamination using gas chromatography linked to mass spectroscopy (GC-MS). (i) Gas chromatography can separate substances in a mixture of compounds. Describe how, as fully as you can. (3) (ii) What information does the molecular ion peak give about the molecule? () (Total 7 marks) Q. Colours are used to coat some chocolate sweets. Some of these colours are given E-numbers. Use the correct word from the box to complete the sentence. additive element fuel An E-number is used to identify a permitted food... () Page 6 of 36

17 (b) Chromatography was used to compare three of the colours used to coat the chocolate sweets. What do these results tell you about these three colours? (3) (Total 4 marks) Q3. (a) Suggest why it is important to be able to identify the colour additives in food () Page 7 of 36

18 (b) A brown colour used in sweets was analysed using chromatography. The results were compared with those from E04 and E33. What do the results tell you about the brown colour and its suitability for use in sweets? (3) (c) Once all the unsuitable colours are removed, the company claims that its sweets are now free from artificial colours. Does this mean that the sweets contain no additives? Explain your answer () (Total 6 marks) Page 8 of 36

19 Q4. This question is about compounds of copper. (a) A student made some copper(ii) sulfate crystals. The flow diagram shows the stages of the preparation of copper(ii) sulfate crystals. Stage Stage Stage 3 (i) The reaction mixture is heated in Stage. Suggest why. () (ii) Complete the equation for this reaction. CuO +... CuSO () (iii) How would the student remove the unreacted copper(ii) oxide in Stage? () (iv) How would the student obtain copper(ii) sulfate crystals from the copper(ii) sulfate solution in Stage 3? () (v) The mass of crystals obtained was less than the student had calculated. Suggest one reason why. () Page 9 of 36

20 (b) The student heated the blue copper(ii) sulfate crystals. The word equation for the reaction is shown below. hydrated copper(ii) sulfate anhydrous copper(ii) sulfate + water blue white (i) What does the symbol mean? () (ii) 300 J of energy are taken in when some blue copper(ii) sulfate crystals are heated. What is the energy change when an excess of water is added to the anhydrous copper(ii) sulfate produced? () (c) A sample of copper nitride contains 3.8 g of copper and 0.8 g of nitrogen. Calculate the empirical formula. You must show all your working to get full marks. Relative atomic masses (A r ): N = 4; Cu = Empirical formula =... (4) (Total 3 marks) Page 0 of 36

21 Q5. Iron is an essential part of the human diet. Iron(II) sulfate is sometimes added to white bread flour to provide some of the iron in a person s diet. (a) The formula of iron(ii) sulfate is FeSO 4 Calculate the relative formula mass (M r ) of FeSO 4 Relative atomic masses: O = 6; S = 3; Fe = The relative formula mass (M r ) =... () (b) What is the mass of one mole of iron(ii) sulfate? Remember to give the unit.... () (c) What mass of iron(ii) sulfate would be needed to provide 8 grams of iron? Remember to give the unit.... () (Total 4 marks) Page of 36

22 M. (a) (i) an alloy (ii) harder (b) (i) 6.5 correct answer with or without working gains marks if no answer or incorrect answer then evidence of correct working [56 + (3x35.5)] gains mark (ii) accept rounding from correct answer with or without working gains marks accept ecf from (b)(i) correctly calculated for marks if no answer or incorrect answer then evidence of 56 / 6.5 or 56 / answer to (b)(i) gains mark [6] M. (a) (i) 40 correct answer with or without working or incorrect working if the answer is incorrect then evidence of gains mark ignore units (ii) 60 correct answer with or without working or incorrect working if the answer is incorrect then evidence of 4/40 or 4/(i) gains mark ecf allowed from part(i) ie 4/(i) 00 ignore units (iii) 5 ecf allowed from parts(i) and (ii) 4/(i) 5 or (ii)/00 5 ignore units Page of 36

23 (b) (i) any two from: ignore gas is lost error in weighing magnesium / magnesium oxide allow some magnesium oxide left in crucible loss of magnesium oxide / magnesium allow they lifted the lid too much allow loss of reactants / products not all of the magnesium has reacted allow not heated enough allow not enough oxygen / air (ii) any two from: ignore fair test check that the result is not anomalous to calculate a mean / average allow improve the accuracy of the mean / average improve the reliability allow make it reliable reduce the effect of errors [9] Page 3 of 36

24 M3. (a) C H O = 0.05 = 0.5 = C H 6 O mark for dividing the correct amount or multiples of correct amount by A r mark for proportions mark for whole number ratio accept any multiple mark for correctly written simplest formula correct formula without working gets only marks correct formula gains full marks provided steps and are correct. ecf can be allowed from step to 3 or step 3 to 4 formula can be in any order eg OH 6 C (b) intermolecular forces / bonds are weak (covalent) bonds are weak = 0 or forces between molecules or bonds between molecules () (attractive) forces are weak = are weak () if no marks awarded, allow low boiling point or small M r for mark (c) (i) to check the safety of the perfume (owtte) accept references to possible harmful / dangerous effects of perfume or possible reactions on skin eg to show it does not damage skin / cause cancer etc. allow to see what it smells like on the skin allow so the company do not have to test on animals Page 4 of 36

25 (ii) any two from: idea from text linked with an explanation the company claim to have tested the product: but we cannot be certain they have or how thorough they are or how accurately reported companies did not disclose how they did their tests: so they could not be checked or so they could not be shown to be reliable / valid or so they could not be repeated or converse eg companies should disclose how they did their tests so that results can be checked etc. companies may not have repeated their tests: so they may not be reliable companies do their own tests: so they may be biased or so they may not be truthful about their results or so they may not be reliable or converse eg independent tests should be done so as to ensure there is no bias etc. the companies are using different tests: so the results cannot be compared or so results will be different or so results will not be fair / valid / reliable or converse eg companies should do the same tests so that the results will be fair etc. companies would not give false information because of damage to reputation or it might lead to litigation [9] M4. 70/56 30/6 division by atomic mass =.5 =.875 proportion Page 5 of 36

26 3 ratio (accept :.5 / 4:6 / etc) allow e.c.f from proportion if sensible attempt at step Fe O 3 formula allow e.c.f from ratio if sensible attempt at step allow correct formula with no working = mark [4] M5. (a).6 / range.5 to.7 correct answer with or without or with wrong working gains marks (accept answers between.5 and.7) if answer incorrect moles of salicylic acid = /38 = moles ie /38 or gains mark or (80/38) gains mark or g 80/38 = (.304 g) gains mark (not.304g alone) (b) 4. range 40.7 to 4.3 accept correct answer with or without or with wrong working for marks ecf ie (. / their answer from (a)) 00 correctly calculated gains marks if answer incorrect percentage yield =. /.6 00 gains mark if they do not have an answer to part (a) or they choose not to use their answer then: yield = (. /.5) 00 () = 44 accept 44 for marks with no working Page 6 of 36

27 (c) any one from: errors in weighing some (of the aspirin) lost do not allow lost as a gas not all of the reactant may have been converted to product eg reaction didn t go to completion allow loss of some reactants the reaction is reversible accept other products / chemicals side reactions ignore waste products reactants impure not heated for long enough not hot enough for reaction to take place (d) any one from: use lower temperature use less fuel / energy ignore references to use of catalyst produce product faster or speed up reaction more product produced in a given time (owtte) increased productivity lowers activation energy [6] Page 7 of 36

28 M6. 35 g gains 3 marks (moles C 8 H 8 = 4 / 4 = mole) moles CO = 8 () mass CO = 8 44 () = 35 g () or mark for each point (ecf allowed between parts) 4 8 () 44 () 4 35 g ecf allowed between parts () [3] M7. (i) correct named instrumental method eg atomic absorption spectroscopy / spectrometry accept atomic / absorption spectroscopy accept aas or mass spectrometry / spectroscopy accept mass spec or infrared (spectrometry) / IR or ultraviolet / spectroscopy / UV or nuclear magnetic spectroscopy / nmr or gas-liquid chromatography / GLC Page 8 of 36

29 (ii) any one from: fast / quick or comment about speed ignore lost ignore human error small amount accept operators do not need chemical skills sensitive / accurate / precise ignore safe / easier to use ease of automation reliable / efficient can be left to run / continuous analysis [] M8. (a) (i) column (ii) mass spectrometer (b) (i) 65 if answer is not correct then evidence of correct working gains one mark. e.g. (0 ) (ii) 0.37% accept 0 / 0.4 / if answer is not correct then evidence of correct working gains one mark. e.g. minimum evidence would be 4/35 (c) any two from: faster more accurate detects smaller amounts Page 9 of 36

30 (d) to avoid bias accept to check / compare the result to improve reliability [0] M9. (a) Mg S O ( 4) or 64 / evidence of all A r s but (M r ) = 0 gains mark gains marks (b) evidence that 4(g) magnesium would produce 0(g) mapesiurn sulphate gains mark or correct scaling by /6 but 0(g) magnesium sulphate gains marks [credit error carried forward from (a) with full marks in (b)] [4] M0. (a) Mg + H + Mg + + H * reactants correct in every detail * products correct in every detail if the spectator ions are sown then () mark should be credited but only if they are shown correctly on both sides e.g. Mg + H + + CI - Mg + + CI - + H (b) 4 (parts) of magnesium (parts) of hydrogen or equally clear working (so) 6 grams/g (are needed) unit required Page 30 of 36

31 (c) (i) two (and no more) atoms shown to be sharing their single electrons examples do not credit if anything which contradicts the impression that these are hydrogen atoms (ii) (single) covalent (bond) (d) ( 00) = 6 (just 6 is worth () mark) 00 = 6 or similar is (0) do not credit and the like [8] M. (a) it is not used up accept does not change accept reusable allow does not react (b) they would melt or they have a low melting point allow would lose their shape ignore soften because there are no cross links or there are weak intermolecular forces accept there are weak bonds / forces between (polymer) chains (c) (i) substances carried by gas ignore reference to mass spectroscopy do not accept other incorrect process described allow named gas (through) column / coil / tube or (through) solid (material) / powder at different speeds accept different retention times Page 3 of 36

32 (ii) (relative) molecular mass / M r allow (relative) formula mass or relative mass ignore relative atomic mass ignore identity of substance / molecule [7] M. (a) additive (b) colour 3 is a mixture of colours and any two from: accept E-number or additive instead of colour ignore comments about height / level colour is made up of only one colour / dye colour is made up of only one colour / dye colour 3 is made up of two colours / dyes or more colours (than colours and ) [4] M3. (a) check if safe to eat / healthy or permitted accept references to allergies / medical problems (b) any three from: accept dye for colour made up of two colours / dots contains an unknown colour / dot contains a harmful colour contains E04 / quinoline yellow or does not contain E33 / brilliant blue further analysis needed 3 Page 3 of 36

33 (c) ignore No or Yes but No must be implied there could be other additives (in the sweets) accept any other type of additives but not colourings could still contain / use / add natural colours accept non-artificial for natural or named natural colours [6] M4. (a) (i) to increase the rate of reaction (ii) H SO 4 on the left hand side H O on right hand side (iii) filtration allow centrifuging or decanting ignore evaporation if after filtration (iv) crystallisation ignore reference to filtration unless given as an alternative or evaporation / heating / boiling / cooling (v) any one from: because of an incomplete reaction accept not all acid reacted accept impure reactants accept unexpected reaction ignore reversible reaction because some (copper sulfate) lost on filtering or when poured into evaporating basin or boiled over or left in apparatus must specify when lost accept some (copper sulfate or acid) spilt weighing error (of copper sulfate) Page 33 of 36

34 (b) (i) reversible (reaction) (ii) 300(J) allow the same (energy) given out / released accept exothermic / ignore increasing or decreasing energy (c) mark for dividing mass by A r (max if A r divided by mass) = 0.06 = 0.0 mark for correct proportions 3 mark for correct whole number ratio (allow multiples). Can be awarded from formula Cu 3 N ecf allowed from step to step 3 and step 3 to step 4 if sensible attempt at step correct formula gains mark [3] M5. (a) 5 correct answer with or without working = marks (4 6) gains mark ignore any units (b) 5g(rams) ecf from the answer to (a) and g must have unit g / gram / gramme / grams etc accept g / mol or g per mole or g mole or g/mol or g per mol or g mol do not accept g m do not accept G Page 34 of 36

35 (c) 76(g) ecf from their answer to (a) or (b) divided by ignore units [4] Page 35 of 36

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