11.6. Alcohols
A subsection of Chemistry, 0620, through 11. Organic chemistry
Listing 10 of 234 questions
Ethanol can be manufactured by fermentation and from ethene. Describe the manufacture of ethanol by fermentation and from ethene. In your answer include • the essential conditions required for each reaction, • one or more relevant word equations. The table shows some properties of different alcohols. alcohol formula melting point / °C boiling point / °C relative viscosity methanol CH4O –94 0.54 ethanol C2H6O –117 1.08 propanol C3H8O –126 1.94 butanol C4H10O –89 2.54 pentanol C5H12O –79 3.47 Deduce the state of methanol at room temperature. Explain your answer. Predict the boiling point of pentanol. Describe how the relative viscosity changes with the number of carbon atoms in the alcohol. Draw the structure of ethanol. Show all of the atoms and all of the bonds. Give one major use of ethanol.
0620_w16_qp_33
THEORY
2016
Paper 3, Variant 3
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Ethanol can be manufactured from ethene or by the fermentation of glucose. Describe these two methods of manufacturing ethanol. In your answer, include ● the names of any additional substances needed, ● the reaction conditions. Ethene is an unsaturated hydrocarbon. Describe how you could distinguish between an unsaturated hydrocarbon and a saturated hydrocarbon using aqueous bromine. Ethene molecules can form polymers. Which phrase describes a polymer? Tick one box. a giant structure containing one type of atom a large molecule formed by cracking monomers a large molecule formed by the addition of many ions a large molecule formed from many monomers Terylene is a polymer. Give one use of Terylene.
0620_w17_qp_32
THEORY
2017
Paper 3, Variant 2
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The chemical equation for the complete combustion of ethanol, C2H5OH, is shown. C2H5OH + 3O2 2CO2 + 3H2O The energy released when one mole of ethanol undergoes complete combustion is 1280 kJ. Part of the energy level diagram for this reaction is shown. energy C2H5OH + 3O2 X Complete the energy level diagram to show ● the products of the reaction, ● the overall energy change of the reaction.  What does X represent? The chemical equation for the complete combustion of methanol, CH3OH, is shown. 2CH3OH + 3O2 2CO2 + 4H2O The equation can be represented as shown. H C H O O O H H H + + O O C O H Use the bond energies in the table to determine the energy change, ΔH, for the complete combustion of one mole of methanol. bond bond energy in kJ / mol C–H C–O O–H O=O C=O ● energy needed to break bonds kJ ● energy released when bonds are formed kJ ● energy change, ΔH, for the complete combustion of one mole of methanol kJ / mol Dodecane is an alkane containing 12 carbon atoms. Ethanol can be manufactured from dodecane in a two-stage process. In stage 1, each molecule of dodecane is converted into three molecules of ethene and one molecule of another hydrocarbon. Name the process which occurs in stage 1. Write a chemical equation for the reaction which occurs in stage 1. In stage 2, ethene reacts with steam to produce ethanol. State two conditions needed for stage 2. Name the type of reaction which occurs in stage 2. Suggest how to test the purity of the ethanol produced. Ethanol can also be manufactured by the fermentation of glucose, C6H12O6. State two conditions needed for the fermentation of glucose. Complete the chemical equation for the fermentation of glucose. C6H12O6 C2H5OH + One disadvantage of fermentation is that the maximum concentration of ethanol produced is about 15%. Suggest why the concentration of ethanol produced by fermentation does not exceed 15%. Give one other disadvantage of manufacturing ethanol by fermentation. Give one advantage, other than cost, of manufacturing ethanol by fermentation. Suggest the name of a process to obtain ethanol from a mixture of ethanol and water. Ethane-1,2-diol has the following structure. H C O H H C H H H O Write the empirical formula of ethane-1,2-diol. Ethane-1,2-diol can undergo condensation polymerisation but cannot undergo addition polymerisation. Explain why ethane-1,2-diol cannot undergo addition polymerisation. Ethane-1,2-diol undergoes condensation polymerisation with molecule Y. The diagrams represent the structures of ethane-1,2-diol and molecule Y. C O H H O O ethane-1,2-diol C O H H O O molecule Y Draw the condensation polymer formed between ethane-1,2-diol and moleculeY. Show one repeat unit. Show all of the atoms and all of the bonds in the linkage. Name the type of condensation polymer formed between ethane-1,2-diol and moleculeY.
0620_w17_qp_42
THEORY
2017
Paper 4, Variant 2
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Questions Discovered
234