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Course Subject Topic Pages Chemistry Chemistry C3 5.1 Structure of alcohols, carboxylic acids and esters Pages 250-251 Learning objectives Learning outcomes Specification link-up Kerboodle Students should learn: the names and formulae of some simple alcohols, carboxylic acids and esters how to show the structures of alcohols, carboxylic acids and esters. Most students should be able to: name an example of an alcohol, carboxylic acid and an ester recognise the formula of an alcohol, carboxylic acid and ester. Some students should also be able to: explain the difference between an alcohol, a carboxylic acid and an ester draw the structure of an alcohol, a carboxylic acid and an ester. Alcohols contain the functional group —OH. Methanol, ethanol and propanol are the first three members of a homologous series of alcohols. [C3.6.1 a)] Ethanoic acid is a member of the carboxylic acids, which have the functional group —COOH. [C3.6.2 a)] … Esters have the functional group —COO—… [C3.6.3 a)] Represent the structures of alcohols in the following forms: Chapter map: Organic chemistry Support: Organic molecules CH3CH2OH [C3.6] Represent the structures of carboxylic acids in the following forms: CH3COOH [C3.6] Lesson structure Support, Extend and Practical notes Starters Link-up – Show students a molecular model of an alkane, its displayed formula and molecular formula. Ask students to suggest what the link is between all of the images [they are all the same compound]. (5 minutes) Definitions – Ask students to think back to the work they did in C1 Chapters 4, 5 and 6. Ask them to define the following key terms: organic compound, molecule, hydrocarbon, alkane, alkene. Support students by encouraging them to work in pairs and use their previous work and the Student Book to help them. Extend students by asking them to define a homologous series [chemical family] and give an example [e.g. alkane, alkene, alcohol]. (10 minutes) Main Give students an A4 sheet of paper and ask them to fold it into equal thirds. At the top of each third they should write the name of one homologous series from: alcohol, carboxylic acid and ester. On one side they should state the characteristics of that homologous series, using secondary sources such as the Student Book and the internet to help them. On the reverse they should draw displayed formulae of some examples of compounds that would be in that group. Students could then use the school’s marking policy to review each other’s work, marking and making suggestions for improvements. Students could then work on the advice of their peers to improve their work before handing it to the teacher for marking. Plenaries Classification – Give students a set of three cards: a red card with the word ‘carboxylic acid’ on it, a blue card with ‘ester’ and a white card with ‘alcohol’. Show students different chemical names, formulae and diagrams of organic molecules. Students have to hold the correct card up to correctly identify which homologous series it belongs to. Support students by using simple organic compounds that they have met during the lesson. They can then look back at their notes to help them. Extend students by using unfamiliar organic compounds. (5 minutes) Circle the group – On the interactive whiteboard, show students a selection of different complex organic molecules, which contain ester, alcohol and carboxylic acid functional groups. Ask for volunteers to circle and label the different functional groups. (5 minutes) Support You can create a ‘cut-and-stick’ activity about the different organic chemicals that students need to study. Students could create a table in which the column headings are ‘alcohol’, ‘carboxylic acid’ and ‘ester’. They could then cut and stick information and examples into the correct columns. Extend Ask students to name simple alcohols and carboxylic acids. The prefix is the same as those used for alkanes and alkenes, however the ending is specific to the homologous series. New AQA GCSE Science © Nelson Thornes Ltd 2011 Course Subject Topic Pages Chemistry Chemistry C3 5.2 Properties and uses of alcohol Pages 252-253 Learning objectives Learning outcomes Specification link-up Kerboodle Students should learn: the properties of alcohols the main uses of alcohols the products of the full oxidation of ethanol. Most students should be able to: describe the properties of alcohols (including their reaction with sodium and their oxidation to carboxylic acids) state the main uses of alcohols write a word equation for the combustion of an alcohol. Some students should also be able to: construct a balanced symbol equation for the combustion of an alcohol. [HT only] Methanol, ethanol and propanol: – dissolve in water to form a neutral solution – react with sodium to produce hydrogen – burn in air – are used as a fuels and solvents, and ethanol is the main alcohol in alcoholic drinks. [C3.6.1 b)] Ethanol can be oxidised to ethanoic acid, either by chemical oxidising agents or by microbial action. Ethanoic acid is the main acid in vinegar. [C3.6.1 c)] Practical: Comparing the reactions of ethanol, methanol and propanol How Science Works: A burning question Lesson structure Support, Extend and Practical notes Starters Connection – Show students an image of a fermentation vessel, a bottle of beer, gasohol station and a bottle of methylated spirit. Ask students to say how all the images are similar [they all contain alcohol]. Support students by encouraging them to think back to the work that they completed in C1 Chapter 5.5 Ethanol. Extend students by asking them to find out more about the constituents of methylated spirits. (5 minutes) Remember – Ask students to recall the products of complete combustion of a hydrocarbon. Encourage students to write a general equation for combustion of a saturated hydrocarbon [hydrocarbon 1 oxygen → carbon dioxide 1 water]. You could extend Higher Tier students by encouraging them to write a general symbol equation for this reaction: Support Give students information about the combustion of the three alcohols. They could then cut-and-stick this information to create their results table. Extend Students could use a data logger to monitor the pH of a solution of ethanol as detailed in the ‘Practical support’. Ask students to print out the data as a graph and add a curve of best fit. Encourage students to annotate the graph to explain the shape of the curve of best fit using oxidation of ethanol in their answers. Practical support Comparing the reactions of methanol, ethanol and propanol Equipment and materials required Three spirit burners, methanol, ethanol, propanol, sodium metal kept under oil, dry boiling tube, boiling-tube holder, tweezers, white tile, filter paper, scalpel, eye protection and safety screen. Details Allow students to ignite each of the spirit burners and observe the flame produced. As a demonstration, wearing eye protection, add 10 cm3 of ethanol to a dry Petri dish. Cut a piece of sodium (maximum 2 mm square) and wipe off the excess oil with filter paper. Using the tweezers, drop the sodium metal into the ethanol and observe. Ensure all of the sodium has reacted before disposing of the solution formed. Safety: CLEAPSS Hazcard 88 Sodium – highly flammable; CLEAPSS Hazcard 40B Methanol – highly flammable/toxic; CLEAPSS Hazcard 40A Ethanol – harmful/highly flammable; CLEAPSS Hazcard 84A Propanol – highly flammable/irritant. For spirit burners see CLEAPSS Guide L195 ‘Safe chemicals, safer reactions’. Oxidation by microbes in air Equipment and materials required Ethanol, universal indicator, 100 cm3 conical flask, 100 cm3 measuring cylinder, 10 cm3 measuring cylinder. Details Measure 50 cm3 of tap water to a conical flask. Add a few drops of universal indicator and then add 5 cm3 of ethanol. Leave the conical flask on a window sill and observe the change in pH over the course of several weeks, swirling the flask occasionally. Keep an identical stoppered flask to compare it with. This experiment works better with beer that has had carbon dioxide removed (shaking or boiling) because flies carrying the microbes are attracted by the smell. Safety: CLEAPSS Hazcard 40A Ethanol – harmful/highly flammable; CLEAPSS Hazcard 32 Universal indicator – highly flammable/irritant. [CxH2x+2 + 1 2 (3x + 1)O2 → xCO2 + (x + 1)H2O]. Give students some examples of hydrocarbons and ask them to use their general equation to write specific equations for the combustion of these saturated hydrocarbons. (10 minutes) Main Allow students to set up a solution of ethanol (less than 15 per cent by volume) and monitor its pH over a number of days (see ‘Practical support’ for more details). Once students have set the experiment up encourage them to make a prediction using scientific ideas in their work. Allow students to observe the combustion of different alcohols (see ‘Practical support’ for more details). Encourage students to draw the displayed formula of each alcohol, and write an equation for the reaction that is occurring. Their observations could be recorded in an appropriate results table. Ask students to create a spider diagram to show the different reactions of ethanol. Students should have the word ethanol in the centre of the page and then add information about the reactions that it undergoes. Higher Tier students could include a balanced symbol equation for the combustion reaction. Plenaries Finish the equation – Ask students to finish the following equations: ethanol 1 [oxygen] → carbon dioxide 1 [water] methanol 1 oxygen → [carbon dioxide] 1 [water] Support students by giving them the missing words. Extend students by asking them to write balanced symbol equations for each reaction and to classify the reactions [oxidation or combustion]. (5 minutes) Flow chart – Ask students to make a flow chart to explain how ethanol is oxidised when it is open to the air. Support students by giving them the outline of the flow chart. (10 minutes) New AQA GCSE Science © Nelson Thornes Ltd 2011 Course Subject Topic Pages Chemistry Chemistry C3 5.3 Carboxylic acids and esters Pages 254-255 Learning objectives Learning outcomes Specification link-up Kerboodle Students should learn: how to recognise carboxylic acids from their properties the uses of carboxylic acids and esters why carboxylic acids are described as weak acids [HT only] how esters can be made. Most students should be able to: describe the properties and an example of a carboxylic acid state a use of a carboxylic acid and an ester describe how to make an ester. Some students should also be able to: explain the difference between strong and weak acids in terms of ionisation [HT only] explain why carboxylic acids are categorised as weak acids. [HT only] Carboxylic acids: – dissolve in water to produce acidic solutions – react with carbonates to produce carbon dioxide – react with alcohols in the presence of an acid catalyst to produce esters – do not ionise completely when dissolved in water and so are weak acids [HT only] – aqueous solutions of weak acids have a higher pH value than aqueous solutions of strong acids with the same concentration [C3.6.2 b)] [HT only] Ethyl ethanoate is the ester produced from ethanol and ethanoic acid. Esters have the functional group — COO—. They are volatile compounds with distinctive smells and are used as flavourings and perfumes. [C3.6.3 a)] Controlled Assessment: C4.1 Plan practical ways to develop and test candiates’ own scientific ideas. [C4.1.1 c)]; C4.3 Collect primary and secondary data. [C4.3.2 a)] Bump up your grade: Organic molecules Extension: Identifying organic molecules Support: Making sense of organic molecules Lesson structure Support, Extend and Practical notes Starters Group – Give students a written selection of 10 different compounds, all of which should be esters, carboxylic acids or alcohols. Some of the compounds should be given as a molecular formula, some as a structural formula and some as a displayed formula. Ask the students to group the compounds by the chemical family (homologous series) they belong to. Support students by giving them a brief definition of each homologous series. Extend students by asking them to try to name the compounds. (5 minutes) Explain – Ask students to explain how they would find out which of two acids (of equal concentration) is strong and which is weak [pH scale/common reactions]. Give students time to think about the question individually. Then split the class into four groups. Ask each group to decide on the method and feed back to the class. (10 minutes) [HT only] Main Allow students to compare ethanoic acid (a weak acid) with hydrochloric acid (a strong acid). Extend students by asking them to write word equations for the reactions with sodium carbonate. Encourage students to reflect on their method and results. Students should be able to suggest that their conclusions about the relative strength of the acids are valid only if the concentration of the two acids is the same. They should also appreciate that using a pH sensor rather than universal indicator gives improved accuracy when finding pH values. Carefully explain the difference between strong and weak acids as opposed to concentrated and dilute solutions of acids. Ask how they can have a solution of a strong acid (high degree of ionisation/dissociation) but with a relatively high pH value, e.g. 5 [very dilute solution]. [HT only] Create a card sort made up of 30 questions and their answers on separate cards. The questions should range from easy questions such as ‘Which functional group is in an alcohol?’ to examination-style questions including equations and summary questions. Students should match the questions with their answers. This activity can be differentiated by giving fewer questions to some students. Students could also work in teams. Then ask students to pick five of the questions, together with their answers, and record them in their notes. Plenaries Bingo – Make bingo cards with six answers on the card, including key words – e.g. ester, alcohol, carboxylic acid, organic chemical. Then ask questions. The students cross off the answer if it appears on their bingo card. The first student to call ‘house’ (with all the answers) is the winner and could get a prize. (5 minutes) Prediction – Ask students to predict how ethanoic acid and hydrochloric acid with the same concentration would react with magnesium. [Both acids would react with the metal to produce hydrogen gas and a metal salt; however, the rate of reaction with hydrochloric acid would be greater.] Support students by encouraging them to work in pairs and reflect on the practical in which they reacted sodium carbonate with the two acids. You may wish to demonstrate the reaction of magnesium with hydrochloric acid to act as memory aid. Extend students by asking them to write equations for these reactions. (10 minutes) Support Students may find it difficult to remember what a carboxylic acid is and how this relates to an ester. Support students by giving them an incomplete summary about carboxylic acids and esters. You could then give them the missing information to complete the summary. Students could then refer to this when tackling other activities. Extend Give students the names of a selection of esters. They should then write a word equation for the formation of that ester. Practical support Comparing ethanoic acid and hydrochloric acid Equipment and materials required Two dropping pipettes, spatula, 10 cm3 measuring cylinder, 2 3 boiling tubes, test‑tube rack, universal indicator or pH sensor with data logger or pH meter, 2 mol/dm3 hydrochloric acid (irritant), 2 mol/dm3 ethanoic acid (irritant), sodium carbonate powder (irritant), eye protection. Details Measure 5 cm3 of hydrochloric acid into a boiling tube and record the pH. Add half a spatula of sodium carbonate powder and observe. Repeat using ethanoic acid. It is worth noting that weak acids are Higher Tier only but reaction with carbonates is Foundation Tier. Safety: CLEAPSS Hazcard 47A Hydrochloric acid – corrosive; CLEAPSS Hazcard 38A Ethanoic acid – corrosive; CLEAPSS Hazcad 95A Sodium carbonate – irritant. New AQA GCSE Science © Nelson Thornes Ltd 2011 Course Subject Topic Pages Chemistry Chemistry C3 5.4 Organic issues Pages 256-257 Learning objectives Learning outcomes Specification link-up Kerboodle Students should learn: that there are advantages and disadvantages to using alcohols, carboxylic acids and esters. Most students should be able to: recall the advantages and disadvantages of using alcohols, carboxylic acids and esters. Some students should also be able to: evaluate in detail the advantages and disadvantages for using alcohols, carboxylic acids and esters. Evaluate the social and economic advantages and disadvantages of the uses of alcohols, carboxylic acids and esters. [C3.6] How Science Works: Drinking and driving Viewpoint: Thinking about drinking WebQuest: Is it time alcohol was banned? Interactive activity: Properties of alcohols, carboxylic acid and esters Revision podcast: Organic families Test yourself: Organic chemistry On your marks: Organic chemistry Examination-style questions: Organic chemistry Answers to examination-style questions: Organic chemistry Teacher notes: Organic chemistry Lesson structure Support, Extend and Practical notes Starters 5, 4, 3, 2, 1 – Ask students to give five uses of alcohols, four names of alcohols, three uses of carboxylic acids, two names of carboxylic acids and one use of an ester. (5 minutes) Drinking and driving – Show students some government material against drinking and driving. Ask students to make a list of three reasons why people do drink alcohol and three disadvantages to drinking alcohol. Encourage volunteers to read out their reasons. Support students by asking them to work in pairs. You could supply them with a number of statements, which they then order as reasons for drinking and disadvantages of drinking. Extend students by asking them to suggest how alcohol can negatively affect a person’s health, finance and social life. (10 minutes) Main In the first activity in the Student Book (‘Raising the cost of alcoholic drinks?’) encourage students to think about how they could discover reliable data about the positive and negative effects of the cost of alcohol and the effect on society. Research the move to increase the price of alcoholic drinks in Scotland in 2010. You may wish to show students news articles such as newspaper clippings and archive articles on news websites about the effect of raising the duty on alcohol. Students could then consider whether the articles are biased and use the information they contain to generate their table of advantages and disadvantages of raising the price of alcoholic drinks. In the second activity in the Student Book (’The way ahead’) you may wish to secure a room-swap to the library. Students could then use secondary sources of information including the Student Book to help them find a solution to the fuel crisis. You could encourage students to think about how they will present their ideas to the class – a podcast, a presentation, a poster, a text message, etc. Each group could then share its work with the rest of the class. At the end of the presentations, students could vote for the idea they think is the most creative, the most scientific and the most likely to be adopted by government. Plenaries Advantage or disadvantage? – Ask students to put their thumb up if the statement is an advantage or down if the statement is a disadvantage. In the UK most of the cost of alcoholic drinks is tax. [advantage or disadvantage, depending on viewpoint] People can be dependent on alcohol. [disadvantage] Alcohol can help relieve stress. [advantage] Alcohol has been linked to high blood pressure. [disadvantage] Alcohol has been linked to heart disease. [disadvantage] New farming land can be created by deforestation. [disadvantage] Biodiesel increases crop prices. [disadvantage] (5 minutes) AfL (Assessment for Learning) – Give the students an examination question and time their attempt. Give the students one minute per mark. After the time is up, show the students the mark scheme and allow them to mark their own work. Ask students to reflect on their answers and suggest how they could improve their examination technique, e.g. answer more briefly. The appropriate tier of entry could be chosen based on the ability of the students in the class. (10 minutes) Support Give students a writing frame to list the advantages and disadvantages of using alcohols. They could be given a list of statements that they could sort into the correct part of the writing frame. To support them further, allow them to contrast the benefits and drawbacks of the uses. Extend Ask students to group the advantages and disadvantages of the uses of these organic chemicals as social, economic or environmental. New AQA GCSE Science © Nelson Thornes Ltd 2011