National 5 Chemistry Exam Revision Nature’s Chemistry Definitions Define the following terms; a) b) c) d) e) f) Fuel Homologous series Isomer Addition reaction Hydrocarbon Combustion Definitions Define the following terms; a) Cracking b) Saturated c) Unsaturated Fuels When a hydrocarbon is burnt, carbon dioxide and water are produced. The following experiment can be used to investigate the products of combustion. Complete the diagram to show the apparatus which would be used to collect the water. Candle wax is a hydrocarbon. Blue cobalt chloride paper and limewater can be used to detect products formed when candle wax is burned. a) Complete and label the diagram to show the arrangement you would use. b) Name the product detected using the blue cobalt chloride paper. c) As the candle burns the funnel becomes coated with soot.Why does this happen? Homologous Series Write the general formula for the; a) b) c) d) Alkanes Alkenes Cycloalkanes Alkanoic acids Which of the following compounds belongs to the same homologous series as the compound with the molecular formula C3H8? 1. A very hot flame is produced when ethyne gas (C2H2) burns in a plentiful supply of oxygen. a) Name the products formed in this reaction. b) Ethyne is the first member of an homologous series called alkynes. Ethyne has the following structure. All the members of the alkyne series have a triple carbon to carbon bond. Complete the table below. Position in series 1st 2nd 3rd Name Ethyne Butyne Molecular formula C2H2 C3H4 Isomers Which of the following is an isomer of the compound shown in the red box? Are these compounds isomers? Are these compounds isomers? Are these compounds isomers? Addition Reactions Draw the full structural formula for the product formed by the reaction of bromine with each of the following hydrocarbons. a) b) but-2-ene c) Cracking The diagram shows how paraffin, C12H26 , can be cracked. a) Name the catalyst used in cracking. One of the reactions taking place when paraffin is cracked is b) Identify molecule X. c) Describe what would be seen when X is added to bromine solution. Identify X a) C8H18 C4H10 + X b) C6H14 C3H6 + X c) C12H26 C6H14 + X d) C10H22 C6H12 + X e) C7H16 C2H6 + X Systematic Naming Name the following; 1. 3. 2. 4. Name the following: 5. 6. 7. 8. Name the following: 9. 10. 11. 12. Drawing full structural formula Draw the full structural formula for; a) b) c) d) e) f) g) h) i) Hexane Cyclobutane The first member of the alkenes The first member of the cycloalkanes Ethanoic acid Propan-2-ol 2,3-dimethylbutane 2-methylbut-1-ene Pent-1-ene Draw the full structural formula for: a) b) c) d) e) f) g) h) 3-ethyl pentanoic acid 2,2 dimethypentan-1-ol CH2CHCH2CH3 3,3-dimethyl hexanoic acid 3methylbutan-1-ol 2-methylhexan-3-ol CH2CH2 2,4-dimethylpentane Functional Groups Which functional group is found in the following; a) b) c) d) Alkenes Alkanols Alkanoic acids Esters a) Linalyl ethanoate is made from an alcohol and ethanoic acid. To which group of compounds does linalyl ethanoate belong? b) Identify the hydroxyl group Methylpropene and an alkane can be use to produce 2,2,4-trimethylpentane, a molecule added to petrol. a) Give the systematic name for the alkane used to produce 2,2,4-trimethylpentane. b) Name the type of chemical reaction shown above. The dehydration of ethanol to ethane was carried out using the following apparatus. 1. Complete the word equation for the reaction Ethanol Ethene + ___________________ 2. As a safety precaution, the delivery tube was removed from the water before heating was stopped. Why? 3. Why is the aluminium oxide catalyst described as being heterogeneous? 4. What would the mass of aluminium oxide catalyst be after the reaction was complete? Esters Name the ester formed between: a) b) c) d) e) f) Methanoic acid and methanol Propanoic acid and ethanol Ethanol and methanoic acid Propanol and butanoic acid Pentanol and methanoic acid Butanoic acid and methanol Uses of Carbon Compounds Uses of Carbon Compounds a) Why can ethanol be described as a renewable source of energy? b) State a use of an ester c) State a use of an alcohol d) State a use of a carboxylic acid Energy from Fuels Calculate Eh from each set of results a) The temperature of 50 cm3 of water is increased by 12 oC. b) The temperature of 250 cm3 of water increases from 21.8 oC to 27.9 oC. c) The temperature of 1000 cm3 of water increases from 8.4 oC to 19.4 oC. d) The temperature of 1cm3 of water is increased by 20.5 oC. Calculations based on equations a) Calculate the mass of carbon dioxide given off when 1g of methanol is burned. CH3OH + 2O2 CO2 + 2H2O b) Calculate the mass of water produced when 3.2g of ethanol is burned. C2H5OH + 2O2 CO2 + 3H2O c) Calculate the mass of oxygen required to burn 50g of methane. CH4 + 2O2 CO2 + 2H2O d) Calculate the mass of water produced when 24g of ethene is burned in oxygen C2H4 + 3O2 2CO2 + 2H2O Problem Solving The combustion of alkanals releases heat energy. PS a) Make a general statement linking the amount of heat energy released and the number of carbon atoms in the alkanal molecules. b) Predict the amount of heat energy released, when 1 mole of pentanal burns. The octane numbers for some hydrocarbons are shown. (i) Predict the octane number for hexane. (ii) State a relationship between the structure of the hydrocarbon and their efficiency as fuels. PS a) Complete the table b) Care had to be taken when using bromine solution. Give a safety precaution, other than eye protection, which should be taken when completing this PPA. Suggest a possible name for hydrocarbon C. c) The diagram below shows how an alkane can be prepared from an alkanoic acid. The equation for the reaction is: Alkanoic acid alkane + carbon dioxide Complete the table to show which alkanoic acid could be used to produce butane. Alkanoic acid Alkane ethanoic acid propanoic acid methane ethane butane Hydroxy acids are compounds that contain both a hydroxyl group and a carboxylic acid group within the same molecule. These compounds are able to form cyclic esters called lactones. Draw the structural formula for the lactone formed when this hydroxyl acid reacts. • Lavender oil is produced from the flowers by steam distillation. The flowers are put into a flask with a little water. Steam from a steam generator is blown through them to extract the oil. The mixture of lavender oil and steam distils over. It is condensed and collected. • The pieces of apparatus which are used to carry out this steam distillation are shown. • show the order in which the pieces of apparatus should be arranged to obtain the mixture.