Download C3.5 - The John Warner School

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