Q1. The figure below shows the displayed structures of five organic compounds, A, B, C, D and E. A B C

Transcription

1 Q. The figure below shows the displayed structures of five organic compounds, A, B, C, D and E. A B C D E (a) Choose which organic compound, A, B, C, D or E, matches the descriptions. You may choose each compound once, more than once or not at all. Write the letter of the compound that: is a saturated hydrocarbon () comes from a homologous series with the general formula C n n () (iii) has the empirical formula C 6 O () (iv) reacts with calcium carbonate to produce carbon dioxide () (v) reacts with compound A to produce compound C. () Page of 3

2 (b) Compound B (C 4 ) and C 8 8 are produced by cracking C 4 30 C C 4 + C 8 8 Give two conditions for cracking. Explain why C 8 8 has a lower boiling point than C 4 30 Compound B is a colourless gas. Give a chemical test and its result to show that compound B is unsaturated. Test... Result (d) Compound B is ethene. Complete the equation to show the formation of poly(ethene) from ethene. (3) (Total 4 marks) Page of 3

3 Q. (a) The hydrocarbon C 6 34 was heated strongly in the absence of air. This is one of the reactions which took place: C 6 34 C C 6 + C 4 This type of reaction is carried out because there is a greater demand for the products than for the original hydrocarbon. Suggest two reasons for this (b) A molecule of the compound methane, C 4, can be shown like this: Draw a molecule of the compound ethene, C 4. Small molecules of substances called monomers can be joined together in polymerisation, eg. ethene poly (ethene). Complete the equation below to show formation of the polymer from the monomer propene. () Page 3 of 3

4 Suggest the name of the polymer formed.... () (Total 6 marks) Q3. To make a plastic, such as poly(ethene), from crude oil involves many processes. (a) Describe how crude oil is separated into fractions (b) Ethene is produced by cracking the hydrocarbons in the naphtha fraction. Balance the symbol equation for this reaction. C 0 decane C 4 0 butane + C 4 ethene () Describe how cracking is carried out. Page 4 of 3

5 Alkanes, such as butane (C 4 0 ), do not form polymers. Alkenes, such as ethene (C 4 ), do form polymers. Explain these statements (d) Ethene molecules form the polymer poly(ethene). One molecule in poly(ethene) will contain thousands of carbon atoms. The diagram represents part of a poly(ethene) molecule. Propene molecules form the polymer poly(propene). Draw a diagram to represent part of a poly(propene) molecule. (Total 9 marks) Q4. Crude oil is used to make useful substances such as alkenes and plastics. (a) The alkene shown is ethene. Page 5 of 3

6 Tick ( ) the correct formula for ethene. Formula ( ) C 4 C 4 C 6 () Tick ( ) the name of the plastic formed when many ethene molecules join together. Name of plastic ( ) Poly(ethene) Poly(ethanol) Poly(propene) () (b) Read the article about plastics and then answer the questions. TE PROBLEM WIT PLASTIC WASTE The UK produces about 3 million tonnes of plastics from crude oil every year. Most of the litter found on UK beaches is plastic waste. 80% of the plastics produced end up in landfill sites. The UK recycles only 7% of plastic waste. Draw a ring around the correct answer in the box to complete the sentence. Litter that is plastic waste needs to be removed from beaches because it decomposes is flammable is not biodegradable. () Suggest a problem caused by 80% of the plastics going to landfill sites () Page 6 of 3

7 (iii) The UK government has set a target to recycle 30% of plastic waste. ow are resources saved by recycling more plastics? () (Total 5 marks) Q5. A molecule of ethene (C 4 ) is represented as: (a) A sample of ethene is shaken with bromine water. Complete the sentence. The bromine water turns from orange to.... () (b) Most ethene is produced by the process of cracking. Complete the sentence. Cracking is a type of thermal.... () Decane (C 0 ) can be cracked to produce ethene (C 4 ) and one other product. Complete the equation to show the formula of the other product. C 0 C () Many molecules of ethene join together to produce poly(ethene). Complete the structure of the polymer in the equation. Page 7 of 3

8 Some carrier bags are made from poly(ethene). Some carrier bags are made from cornstarch. Suggest two benefits of using cornstarch instead of poly(ethene) to make carrier bags. (Total 7 marks) Page 8 of 3

9 M. (a) D B (iii) A (iv) E (v) E (b) high temperature ignore hot / heat allow temperature quoted (range C) catalyst or steam C 8 8 smaller molecule It = C 8 8 therefore there are weaker intermolecular forces allow intermolecular bonds do not accept breaking covalent bonds / bonds or weaker intermolecular forces in C 8 8 () allow intermolecular bonds so less energy to break () add bromine water turns (from orange / yellow / red / brown) to colourless or decolourises do not accept discoloured ignore clear incorrect test = 0 marks Page 9 of 3

10 (d) single C C bond four carbon-hydrogen bonds in place and two trailing bonds structure in brackets and n at bottom right [4] M. (a) smaller, more useful molecules more reactive (molecules)/(molecules) used to make plastics more easily ignited/better fuels produces unsaturated compounds/alkenes any two for mark each (b) gains mark but gains marks for mark poly(propene) (N.B. brackets not required; allow polypropylene ) for mark [6] Page 0 of 3

11 M3. (a) vaporise / evaporate allow boil for vaporise different condensing points / temperatures accept condense at different levels ignore different size molecules or different densities mention of cracking = max allow boils at different temperatures and condenses for marks if no other marks awarded allow fractional distillation for mark (b) 3 (C 4 ) accept +C 4 8 (decane / naphtha / hydrocarbon) vaporise / evaporate allow crude oil allow boil for vaporise (passed over) a catalyst / alumina / porous pot ignore other names of catalysts any two from: they must be clarified alkanes / butane (molecules) do not have a (carbon carbon) double bond / are saturated / have (carbon carbon) single bonds alkenes / ethene (molecules) have (carbon carbon) double bonds or are unsaturated alkenes / ethene molecules are able to bond to other molecules (d) single bonds between carbon atoms C - C the -C 3 group appears on each pair of carbons on the chain NB any double bonds = 0 marks [9] Page of 3

12 M4. (a) C 4 poly(ethene) (b) is not biodegradable not enough landfill sites / space accept landfill sites are filling up or plastics remain for years or plastics not broken down ignore cost / waste of resources / not biodegradable / wildlife (iii) less (crude) oil / fuels / energy used accept (crude) oil is a non-renewable resource [5] M5. (a) colourless ignore clear (b) decomposition C 8 8 two single trailing bonds extending from the carbons (through the brackets) mark five single bonds ( C C bond and 4 C bonds) mark any two from: (polymers made from) cornstarch are biodegradable less space needed in landfill sites polymers from cornstarch come from a renewable source. allow converse for poly(ethene) [7] Page of 3

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