Edexcel AS Level Chemistry:A guide to purposeful practical work

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The changes to the GCE AS and A level which took effect for first teaching in 2015 implemented a significant change in the approach take to practical and investigative science. In particular, the emphasis has shifted from practical skills tasks set by the board and marked by teachers to a much more open ended practical endorsement scheme. Previously, the majority of marks awarded for Assessment Objective 3 ‘How Science Works’, (HSW) were for the practical skills tasks. This situation has now significantly changed.

Specification 8CH0 for first assessment in 2016 requires students to record their practical achievement and experiences in a lab book similar to an undergraduate lab book. They are required to complete a minimum of eight practical activities which they record in a lab book or practical portfolio, which is assessed by the centre and endorsed by the board. They do not provide marks for the final GCE grade but aspects of practical and investigative chemistry are assessed as parts of AO1, AO2 and AO3 within the written papers. The clear implication of this is that students require teaching and learning which nourishes their practical and investigative chemistry skills and abilities. Other aspects of the practical work suggested in this guide support students’ conceptual understanding of chemistry, in particular, the use of models and analogies. The practical and investigative science skills within this course build upon the KS4 HSW skills acquired by students within their GCSE curriculum.

Curriculum time is limited and it is important that all activities especially practical and investigative activities are purposeful and make a worthwhile contribution to learning. Practical work which does not contribute to learning wastes valuable curriculum time. The ‘Getting Practical’ project was based on the paper, Analysing practical activities to assess and improve effectiveness: The Practical Activity Analysis Inventory (PAAI), by Robin Millar of York University, 2009. It promotes purposeful and effective practical work where students engage fully with practical work: ‘Hands on! Minds on!’ This document aims to identify opportunity for effective practical work which supports students to work scientifically. It is not expected that schools will attempt all of these practical activities. However, it is hoped that teachers will see the value of these possibilities for practical work, especially in conjunction with the suggested purposes.

As with all practical work, always follow your employer’s risk assessment (which normally follows CLEAPSS or SSERC guidance). Check that the safety advice, where given on websites, is in accordance with your employer’s safety advice.

Getting PracticalThe purpose of the practical work identified in this document relate to Getting Practical: Improving Practical Work in Science http://www.gettingpractical.org.uk/ There is a detailed paper which supports the Getting Practical project written by Robin Millar entitled Analysing practical activities to assess and improve effectiveness: The Practical Activity Analysis Inventory (PAAI) A copy of this paper can be found at: https://www.rsc.org/cpd/teachers/content/filerepository/frg/pdf/ResearchbyMillar.pdfGetting Practical learning objectives:

A: By doing this activity, pupils should develop their understanding of the natural world A1: Pupils can recall an observable feature of an object, or material, or event A2: Pupils can recall a ‘pattern’ in observations (e.g. a similarity, difference, trend, relationship) A3: Pupils can demonstrate understanding of a scientific idea, or concept, or explanation, or model, or theory

B: By doing this activity, pupils should learn how to use a piece of laboratory equipment or follow a standard practical procedure B1: Pupils can use a piece of equipment, or follow a practical procedure, that they have not previously met B2: Pupils are better at using a piece of equipment, or following a practical procedure, that they have previously met

C: By doing this activity, pupils should develop their understanding of the scientific approach to enquiry C1: Pupils have a better general understanding of scientific enquiry C2: Pupils have a better understanding of some specific aspects of scientific enquiry

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This is one of a series of documents designed to support science departments to integrate engaging and purposeful practical and investigative science activities within their current schemes of learning. They highlight opportunities throughout the AS Level Specification and identify possible purposes for each activity relating to the ‘Getting Practical’ project.

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Possible practical activities

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Excerpt from specification

Practical work is central to any study of chemistry. For this reason, the specification includes eight core practical activities which form a thread linking theoretical knowledge and understanding to practical scenarios. In following this thread, students will build on practical skills learned at GCSE, becoming confident practical chemists, handling apparatus competently and safely. Using a variety of apparatus and techniques, they should be able to design and carry out both the core practical activities and their own investigations, collecting data which can be analysed and used to draw valid conclusions.One important aspect of practical work is the ability to evaluate and manage potential risks. The variety of different practical techniques and scenarios in the core practical activities give students scope to consider risk management in different contexts.Students should also consider the ethical issues presented by their work which, in the laboratory, might include consideration for using minimum quantities of resources, such as through microscale procedures; the safe disposal of waste materials, especially from organic reactions; and appropriate consideration for other people involved in their own work or who is working nearby.Also central to the development of practical skills is the ability to communicate information and ideas through the use of appropriate terminology and ICT. Being able to communicate clearly the findings of practical work is arguably as important as the collection of accurate data. In carrying out practical activities, students will be expected to use their knowledge and understanding to pose scientific questions which can be investigated through experimental activities. Such activities will enable students to collect data, analyse it for correlations and causal relationships, and to develop solutions to the questions posed.

Section 1.1-1.5

Students could make models to show atomic structure. They should interrogate and argue the strengths and weaknesses of these modelsRSC Resource: The Atom Detectives, http://www.rsc.org/learn-chemistry/resource/res00001332/the-atom-detectives Catalyst: Models of the atom, David Sang, https://www.stem.org.uk/system/files/elibrary-resources/legacy_files_migrated/38397-Catalyst_25_4_616.pdf One of the main purposes of this approach is to convey the idea that science is evolving

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Section 1.8-1.10

Introduce mass spectrometry (which is covered in more detail in section 4.2.4). Interpret isotopic masses from an MS trace. If possible, show a physics deflection tube which graphically demonstrates the deflection of charged particles (in this case electrons) by an electric field

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Stand RA67550Deflection Tube RA67580

Section 1.16-1.21

Electron structure:Students can model the shapes of s and p orbitals using pipe cleaners, with beads as electrons. Alternatively, they can ‘go large’ by using hula hoops and pompoms as electrons. These models demonstrate the limitations of using two-dimensional models to depict three-dimensional orbitals, and how difficult it is to visualise the orbitals in 2D.

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Section 1.11-1.14 1.23-1.26

This is a very theoretical and conceptual section of the specification. However, there are ways in which you can support students• Have physical samples of elements from the same Period sealed in sample bottles.• Make and use ‘Top Trumps type element cards as information sources for graphing

trends in physical properties• Make and use element cards which have had the names replaced by fictitious names.

Students use the cards for element grouping exercises without using prior knowledge of the periodic table

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Element Cards VI130500

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Section 2.1-2.5

Ionic bonding Lattice structures can be neatly demonstrated by using Molymod. The lattice allows us to see a compound such as salt as a solid but not as a solution once the lattice structure is lost. Students can test the type of bonding in different compounds by dissolving them and testing their electrical conductivity.

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Sodium Chloride MO20000Ice MO20045Molecular Orbital Organic Structures Set MO120215Student Multimeter EL52400Atomic Orbital Set MO120210

Section 2.6

You can graphically demonstrate ion migration by the electrolysis of copper (II) chromate(VI) in a U-Tube. The blue Cu2+ ions separate from the yellow CrO4

2- ions http://www.rsc.org/learn-chemistry/resource/res00000997/migration-of-coloured-ions

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U-tube AB00025Carbon Rods EL06886Electrode Connector EL150426

Section 2.7-2.11

For molecular structures, Molymod is excellent for showing single and multiple bonds in molecules such as ethane, ethene and ethyne. It also helps to explain molecule shapes and explain the influence on shape of electron lone pairs.To explain electron pair repulsion and the difference between trigonal plane and pyramidal molecules, balloon modelling is ideal. Structure and bonding:A good way to show the degree of bonds polarity in different liquid compounds is by setting up a series of burettes with different liquids such as water, ethanol and cyclohexane (propanone and methylbenzene are also suggested in the reference). Electrostatically charged rods will deflect water the most, then ethanol but cyclohexane will hardly be deflected. References: Chemistry in Context (Nelson Graham Hill and John Holman); OCR Salters AS and A LEVEL Bonding and structure delivery guide. A video of the demonstration can be viewed here: http://www.chemistry-videos.org.uk/chem%20clips/PR%20Deflecting%20jets/Deflecting%20jets%20PR5-1.wmv To illustrate electronegativity and bond polarity, students could investigate the anomalous properties of water. The difference in density is explained by the open lattice structure in ice which reduces density. You could set up a circus of different compounds which have a mixture of solid and liquid to show that most solids sink in their liquid. Suitable solids include salol, paraffin wax and stearic acid. To show charge neutralisation within compounds, you can use discs cut out from card or Post-It notes which have the species formula and charge. As an alternative, you can introduce the ‘hook model’ which allows for the determination of formulae of covalent as well as ionic compounds.

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Ebonite Rod EL18665Glass Rod EL18666Perspex Rod EL18667Nylon Rod EL130470Cotton Cloths CL04240Silk Cloth EL81495Modular Burette BU03765Sodium Chloride MO20000Ice MO20045Molecular Orbital Organic Structures Set MO120215Student Multimeter EL52400Atomic Orbital Set MO120210

Section 3.1-3.13

Redox reactions:• The reduction of copper oxide with methane in a ventilated test tube• The formation of bleaches from the reaction of chlorine or bromine with waterStudents can model redox reactions in terms of electron transfer by role play: in a fake marriage, they transfer electrons instead of a ring. You can quickly check students’ understanding of oxidation number by using mini whiteboards or flashcards: with numbers +7 to -7

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Combustion Tube TU16350

Section 4.1-4.3

Group 2 Metals and their reactions:Reactions of magnesium and calcium with water, oxygen and chlorine. Compare the relative reactivity of the two metals and use the reactions and ideas about bonding to generate balanced symbol equations with state symbols

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Section 4.4

Investigating the reaction of Group 2 oxides with water and dilute acid,Slake calcium oxide to form limewater and use the reactions and ideas about bonding to generate balanced symbol equations with state symbols. This could follow on from 4.6: The production of quicklime from limestone.

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Section 4.5

Investigate solubility trends of the Group 1 and Group 2 hydroxides and sulfates. This can be done as a ‘paper’ exercise whereby students use research to find the relevant data. Alternatively you can set this as a problem solving type activities whereby students devise methods to determine solubility data.Investigate the reactions of the hydroxides. Magnesium hydroxide is insoluble and so is good for making indigestion tablets: its insoluble nature means that the hydroxide ion concentration does not get too high, which could otherwise cause tissue damage. Investigate indigestion cures through modelling. Determine the advantages and disadvantages of each of the different cures.Undertake quantitative analysis of actual antacid cures. This investigation offers an opportunity for research and planning, as well as collecting, presenting, analysing and evaluating evidence.

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Section 4.6

Investigate the thermal stability of Group 1 and Group 2 nitrates and carbonates. Investigate the thermal decomposition of calcium carbonate to produce calcium oxide.

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Section 4.7

Investigate flame tests of Group 1 and 2 compounds. Relate this to section 1.15 and electron transitions.This could contribute to CORE PRACTICAL 7: Analysis of some inorganic and organic unknowns

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Flame Test Glasses FL07720Platinum Wire FL07725

Section 4.9-4.14

The halogens:• Students can investigate the sublimation of iodine in a lab without the need for a

fumes cupboard provided that the CLEAPSS guidance on Hazcard 54 is followed along with a suitable risk assessment. Students can use up to 0.25 g in a test tube which has a mineral wool plug in the neck of the tube to prevent iodine vapour leaving the tube. The following link shows a more sophisticated demonstration of sublimation in which large iodine crystals can be grown http://www.rsc.org/eic/2013/10/exchem0113-sublime-iodine

• Halide displacement can be shown using halogens with halides in cyclohexane http://www.rsc.org/learn-chemistry/resource/res00000733/reactions-of-halogens-as-aqueous-solutions

• http://www.rsc.org/learn-chemistry/resource/res00000403/reactions-of-the-halogens

• Make chlorine water and/or bromine water to demonstrate their bleaching properties, or show bleaching with gases. Making chlorine water is a good example of a disproportionation reaction http://www.rsc.org/learn-chemistry/resource/res00000403/reactions-of-the-halogens

• The RSC has produced a problem-based practical activity about cleaning solutions. In this activity, students determine the amount of NaOCl in various bleach samples (found by reacting a known quantity of each bleach with hydrogen peroxide and measuring the amount of oxygen produced). This is a second example of a disproportionation reaction. http://www.rsc.org/learn-chemistry/resource/res00000939/problem-based-practical-activities

• Testing of halide ions with silver nitrate solution distinguishing between Cl and Br by holding up against paper

• Investigating the solubility of calcium chloride in water, ethanol and cyclohexane. Compare the degree of solubility by using silver nitrate solution http://blogs.ubc.ca/msk2015/files/2015/02/Lab-Effect-of-structure-and-bonding-on-molecules.pdf (see Hazcards 87 and CLEAPSS Handbook Section 13.8 for guidance regarding silver nitrate titrations. Link the solubility of calcium chloride back to the polarity of solvents covered in 2.2.2

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Section 4.15

Revise testing of ions CO32-, SO4

2-, Cl -, Br -, I -. This could contribute to CORE PRACTICAL 7: Analysis of some inorganic and organic unknowns. The RSC resource sheet, ‘Testing salts for anions and cations’ is a useful resource (although the test for cations does not work as well as the tests for anion do!) http://www.rsc.org/learn-chemistry/resource/res00000464/testing-salts-for-anions-and-cations

Please refer to Timstar Chemicals List

Section 5.1-5.3

To convey the idea of mole you could:• Provide students with samples of the same numbers of sweets in jars. Different types of

sweet will have different masses and volumes • Provide samples of different elements e.g. 32g of sulfur, 56g of iron as comparison.

Then you can work down to atoms, sub-atomic particles and isotopes e.g. Cl 35.5, Cu 63.5

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Periodic Table VI77054Element Cards VI130500

Section 5.4-5.8

Empirical formulae and reacting masses CORE PRACTICAL 1: Measure the molar volume of a gas: Determination of relative atomic mass of hydrogen using the RSC resource (Reaction of hydrochloric acid with magnesium and collecting and measuring the volume of hydrogen with a burette http://www.rsc.org/learn-chemistry/resource/res00000401/determination-of-relative-atomic-mass • Determination of the formula of hydrated copper sulfate empirically

http://www.rsc.org/learn-chemistry/resource/res00000436/finding-the-formula-of-hydrated-copper-ii-sulfate

• As an alternative, to copper sulfate. You could use hydrated Iron (II) sulfate if copper sulfate is considered too familiar

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Modular Burette BU03765Burette Stand BU100588Burette Clamp ST14062Combustion Tube TU16350Crucible Lid 15ml CR05190

Section 5.9-5.10

Investigating reacting volumes of gasesIn this activity, students react different bleaches with hydrogen peroxide and measure the volume of oxygen collected. The purpose is to use the volume of oxygen evolved to determine the sodium hypochlorite content of different bleaches.http://www.rsc.org/learn-chemistry/resource/res00000939/problem-based-practical-activitiesAs an alternative, students can determine the composition of copper (II) carbonate by thermal decomposition to copper oxide and then reduction of copper oxide to copper by natural gas http://www.rsc.org/learn-chemistry/resource/res00000727/finding-the-formula-of-copper-ii-oxide

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Section 5.11-5.14

Mole concentrationStudents can try the standard solution challenge in which they make up a 250 ml standard solution e.g. NaOH using correct technique, and then check the accuracy of their solution by titration with hydrochloric acid. This would support CORE PRACTICAL 3: Find the concentration of a solution of hydrochloric acidThis is a good opportunity for students to do another titration to reinforce the technique early in the course, preferably with a different indicator (such as phenolphthalein or methyl orange) to their first titration. This could be a titration to determine the concentration of limewater or to determine the relative molecular mass of washing soda (by making a standard solution, then titrating against hydrochloric acid using methyl orange indicator). A suitable acid for CORE PRACTICAL 2: Prepare a standard solution from a solid acid and use it to find the concentration of a solution of sodium hydroxide is ethanedioic (oxalic) acid (See CLEAPSS Hazcard 36A Ethanedioic acid and its salts). There is more detailed guidance available from the Education Scotland document downloadable from http://www.educationscotland.gov.uk/resources/nq/c/nqresource_tcm4723691.asp?strReferringChannel=educationscotland&strReferringPageID=tcm:4-615801-64&class=l1+d86716 Percentage yield and atom economy • An experiment which demonstrates many aspects of good practical chemistry

techniques is the reaction of magnesium with oxygen in a crucible, to determine the formula of magnesium oxide empirically. A known mass (such as 0.24 g) of magnesium ribbon, wound as an open spiral is heated to constant mass in a crucible http://www.rsc.org/learn-chemistry/resource/res00000718/the-change-in-mass-when-magnesium-burns?cmpid=CMP00005934

• An experiment to determine the yield of copper(II) from the reaction between copper (II) oxide and dilute hydrochloric acid allows calculations of theoretical mass based on the volume of hydrochloric acid of known concentration, and brings in ideas about stoichiometry. The hydrochloric acid volume can be measured using a burette or pipette.

• Atom economy: students could investigate methods to extract the maximum copper from a copper ‘ore’. They could compare reduction (finding the mass of the copper nugget after removal of impurities) with electrolysis of a copper solution extracted from the ‘ore’ using dilute sulfuric acid.

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Volumetric Flask 250ml FL130625Pipette Bulb 25ml PI12225Modular Burette BU03765Burette Stand BU100588Burette Clamp ST14062Crucible + Lid 15ml CR05190Pipe Clay Triangle TR16255Electrolysis Cells EL06891 Carbon Rods EL06886

Section 5.15

Displacement reactions using metals and metal solutions http://www.rsc.org/learn-chemistry/resource/res00000720/displacement-reactions-between-metals-and-their-salts One particularly aesthetic example uses a piece of copper wire made into the shape of a Christmas tree, and suspended in a solution of silver nitrate Precipitation reaction may be combined with tests for cations and anions Testing for ions CO3

2-, SO42-, Cl -, Br -, I -. This can contribute to CORE PRACTICAL 7:

Analysis of some inorganic and organic unknowns .The RSC resource sheet, ‘Testing salts for anions and cations’ is a useful resource (although the test for cations does not work as well as the tests for anion do!) http://www.rsc.org/learn-chemistry/resource/res00000464/testing-salts-for-anions-and-cations?cmpid=CMP00000534

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Topic 6 throughout

A really important concept for students to grasp is that two-dimensional representations of organic molecules bear little resemblance to the actual molecule shapes. Using Molymod to graphically demonstrate actual molecule shapes on a regular basis is really helpful to students especially getting them to make and then handle the molecules. This is particularly true for looking at functional groups and isomers

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Introductory Set MO11301Organic and Inorganic Teacher Set MO11303Organic and Inorganic Student Set MO11306Shapes of Molecule Set MO55810

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Section 6.10

Fractional distillation of ‘crude oil’ (See CLEAPSS guidance) offers a good introduction to the physical properties of the alkanes, enabling comparison of boiling points with viscosity and flammability. Students can model alkanes by making paper chains or by using string. These models will show that longer chains have greater intermolecular interaction.

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14/23 BU/M Set JG26380Organic Set JG26360Distillation Apparatus JG26380Heating Mantle 100ml HE08942Thermometer -10 to 300˚C TH29510

Section 6.18-6.29

Properties of alkenes:Decolourisation of bromine water as the test for unsaturation in a carbon chain. This could contribute to CORE PRACTICAL 7: Analysis of some inorganic and organic unknowns. Use Molymod to explain cis-trans isomerism and the inability of double bonds in alkenes to rotate.Extraction of Limonene from orange peel: http://www.rsc.org/learn-chemistry/resource/res00000692/extracting-limonene-from-oranges Students steam-distil the limonene using Quickfit distillation apparatus. You may wish students to separate the limonene form the aqueous layer by using a separating funnel rather than the dropping pipette test suggested in the reference. The limonene can be tested with bromine water.Reaction mechanisms are highly conceptual and can cause problems for students. On novel and engaging way to help students to visualise reaction mechanisms is by modelling the using ‘Smarties’ as electrons with the molecules drawn on A3 paper. Students can take photos of the individual mechanism stages and use these to create a story board using ‘Comic Life’ software or similar.Students can model polymers using different approaches including: • Paperclip chains. These allow side chains and cross-links• Paper chains made from strips of paper. These allow side chains and cross-links• Using themselves linking with arms as bonds: two students form monomers with their

arms as double bonds and student pairs polymerise with each other by making and breaking bonds

• WhiteboardsThe real benefits of making polymer models is that student can interrogate the models for strengths and weaknesses, and suggest improvements or better models.

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Organic Set - Teacher MO11302Organic Set - Student MO11305Organic and Inorganic Chemistry Set MO3060414/23 BU/M Set JG26380Organic Set JG26360Distillation Apparatus QDA1/22Heating Mantle 50ml HE102330Heating Mantle 100ml HE08942Thermometer -10 to 300˚C TH29510

Section 6.30-6.36

HaloalkanesHydrolysis of haloalkanes using alkali solution to investigate the rate of reaction of primary, secondary and tertiary haloalkanes-see http://www.york.ac.uk/org/seg/salters/ChemistryArchive/ResourceSheets/halogenoalkanes.PDF This could support CORE PRACTICAL 4: Investigation of the rates of hydrolysis of some halogenoalkanesAlternatively, water can be used for the hydrolysis with silver nitrate solution present as a test to determine the nature of the halogen in the haloalkane. This can be used as practice for the qualitative analysis of organic functional groups. See http://www.chemguide.co.uk/organicprops/haloalkanes/agno3.html This could contribute to CORE PRACTICAL 7: Analysis of some inorganic and organic unknownsTo explore the mechanisms of free radical reactions such as those which occur in CFCs in the upper atmosphere, there is a need for modelling. Once again, Smarties and ‘Comic Life’ or time lapse photography offer an engaging way for students to explore the mechanisms.

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Section 6.37-6.39

Alcohols Revise the polarity of the O-H bond in alcohols by reminding students of the electrostatic deflection experiment described in Section 2.2.2Oxidise ethanol to ethanal and ethanoic acid by using acidified sodium or potassium dichromate. The reference suggests this as a test tube reaction but using distillation or reflux allows for good coverage of CORE PRACTICAL 5: The oxidation of ethanol and testing the reaction products supports the qualitative analysis of organic functional groups: http://www.rsc.org/learn-chemistry/resource/res00001757/oxidation-of-ethanol CORE PRACTICAL 6: Chlorination of 2-methylpropan-2-ol using concentrated hydrochloric acid is nicely addressed by the resource http://www.rsc.org/learn-chemistry/resource/res00000558/the-conversion-of-alcohols-to-halogenoalkanes

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14/23 BU/M Set JG26380Organic Set JG26360Distillation Apparatus QDA1/22Heating Mantle 50ml HE102330Heating Mantle 100ml HE08942Thermometer -10 to 300˚C TH29510

Section 7.1-7.2

Analytical techniquesIR spectroscopy and MS provide a challenge for schools. However, RSC has provided support through:• Spectraschool: An online tutorial with animations which explains the principles of IR

and the theory which underpins it: http://www.rsc.org/learn-chemistry/collections/spectroscopy/introduction#

• Spectroscopy in a suitcase: Spectroscopy in a Suitcase gives school students the chance to learn about spectroscopy through hands-on experience. University students and staff deliver the workshops which have a strong emphasis on encouraging school pupils to consider studying chemistry and also highlight the career opportunities available with chemistry qualifications. http://www.rsc.org/learn-chemistry/resource/res00000280/spectroscopy-in-a-suitcase-resources

In addition to the RSC resources, you may wish to make links with a local university chemistry department or a local company. These may be able to analyse samples for you or provide a workshop for your students. CORE PRACTICAL 7: Analysis of some inorganic and organic unknownsAlthough many of these tests may already have been covered, the spec suggests that the core practical is done here. You could provide students with a circus comprising of different testing stations to identify several unknown organic liquids and inorganic solutions.http://www.rsc.org/learn-chemistry/resource/res00000464/testing-salts-for-anions-and-cations http://www.rsc.org/learn-chemistry/resource/res00000758/testing-for-negative-ions http://www.rsc.org/learn-chemistry/resource/res00000552/testing-for-unsaturation-using-brominehttp://www.chemguide.co.uk/organicprops/haloalkanes/agno3.html

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Spectrophotometer SP106234Flame Test Glasses FL07720Platinum Wire FL07725

Section 8.4

Enthalpy changesQualitative circus of reactions: • Reaction of sodium hydrogencarbonate solution and citric acid, Reaction of copper(II)

sulfate solution and magnesium powder, ammonium chloride dissolving in water, reaction of sulfuric acid and magnesium ribbon, combustion of fuels, reaction of sodium hydroxide solution and dilute hydrochloric acid and hand-warmers (which also demonstrate principles of reversibility and application of ideas). Some of these activities are explained in more detail in the RSC resource, ‘Exothermic or endothermic’, http://www.rsc.org/learn-chemistry/resource/res00000406/exothermic-or-endothermic

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Section 8.5-8.8

Quantitative investigations• Reaction of sodium hydrogencarbonate solution and citric acid, Reaction of copper(II)

sulfate solution and magnesium powder, reaction of sulfuric acid and magnesium ribbon, reaction of sodium hydroxide solution and dilute hydrochloric acid. This is explained in more detail in the RSC resource, ‘Heats of reaction (exothermic or endothermic reactions)’, http://www.rsc.org/learn-chemistry/resource/res00000468/heats-of-reaction

• Hess’s law verification investigations. There is an RSC resource which approaches Hess’s law theoretically http://www.rsc.org/learn-chemistry/resource/res00000954/starters-for-ten This can be combined with an investigation into the combustion of different alcohols in spirit burners to determine the enthalpies of combustion: http://www.rsc.org/learn-chemistry/resource/res00001733/heat-energy-from-alcohols The actual experiment can be compared with a simulation from Focus Educational Software: http://www.rsc.org/learn-chemistry/resource/res00002094/heat-of-combustion-of-alcohols-simulation

• Comparing different calorimeter designs and evaluating camping pan efficiency (e.g. JetBoil design vs. standard camping billy)

• Neutralisation of acids by alkalis: The enthalpy change is independent of the acid and alkali used. The RSC investigation, ‘Energy changes in neutralisation on microscale’, provides a different way of approaching the investigation. http://www.rsc.org/learn-chemistry/resource/res00000525/energy-changes-in-neutralisation-on-microscale This investigation is suitable as CORE PRACTICAL 8: To determine the enthalpy change of a reaction using Hess’s Law

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Vision DA130585V-Log 4 DA150100V-Log 8 DA150140Temperature Sensor DA130870Polystyrene Cup CU05395Thermometer -10 to 110˚C TH15440Thermometer Strips TH106370Spirit Burner Glass BU03877Spirit Burner Stainless Steel BU110905Copper Calorimeter HE18722Aluminium Calorimeter HE82324Food Calorimeter HE82320

Section 9.3

Reaction rates:There are several tried and tested reactions suitable for investigating rates of reaction. These include:• sodium thiosulfate/hydrochloric acid

http://www.rsc.org/learn-chemistry/resource/res00000448/the-effect-of-temperature-on-reaction-rate http://www.rsc.org/learn-chemistry/resource/res00000743/the-effect-of-concentration-on-reaction-rate

• the iodine clock http://www.rsc.org/learn-chemistry/resource/res00000744/iodine-clock-reaction

• Magnesium/hydrochloric acid http://www.rsc.org/learn-chemistry/resource/res00001916/the-rate-of-reaction-of-magnesium-with-hydrochloric-acid

• Marble chips/hydrochloric acidIt may be worth keeping the sodium thiosulfate/hydrochloric investigation for A2 when covering the Arrhenius equation.

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Section 9.5-9.7

Catalysis:A good open ended investigation is into the factors which affect the rate of catalysis for the hydrogen peroxide decomposition reaction (students must not exceed a temperature of 50˚C). Students can investigate the effect of temperature and catalyst surface area using the same mass of liver or potato each time, but chopped finer to increase the surface area. http://www.rsc.org/learn-chemistry/resource/res00000831/hydrogen-peroxide-decomposition. This investigation could support PAG 9: Rates of reaction – continuous monitoring method by monitoring the rate at which oxygen is evolved from gas collection, or by mass loss.To investigate homogeneous catalysis, students can investigate the role of sulfuric acid on the ester synthesis reaction http://www.rsc.org/learn-chemistry/resource/res00001743/making-esters-from-alcohols-and-acids Boltzmann distribution:A simple way to model the Boltzmann distribution involves the a rope as the ‘line’ on the graph - to show an increase in temperature, the rope is pulled to stretch the curve over a greater range of molecular velocities and this lowers the curve.

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Gas Syringe SY14858Vision DA130585V-Log 4 DA150100V-Log 8 DA150140Balance Adaptor DA130630Scout Pro BA90300

Section 10.1-10.4

EquilibriumStudents can investigate the equilibrium between iodine in an aqueous solution and an iodine solution in cyclohexane. http://www.rsc.org/learn-chemistry/resource/res00001723/distribution-of-iodine-between-two-immiscible-solvents Investigating the equilibrium between nitrogen dioxide and dinitrogen tetroxide. Instead of using a salt bath, to achieve lower temperatures, use a dry ice/acetone (propanone) http://www.rsc.org/learn-chemistry/resource/res00001739/le-chateliers-principle-the-equilibrium-between-nitrogen-dioxide-and-dinitrogen-tetroxide Investigating the equilibrium between cobalt complex ions, [Co(H2O)6]2+ and [CoCl4]2- http://www.rsc.org/learn-chemistry/resource/res00000001/the-equilibrium-between-two-coloured-cobalt-species Investigating the equilibrium between dichromate (VI) and chromate (VI) ions in solution http://www.rsc.org/learn-chemistry/resource/res00001710/an-equilibrium-involving-chromate-vi-and-dichromate-vi-ions

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Gas Syringe SY148583 Way Tap SY58480Thermometer -10 to 110˚C TH15440Boiling Tube with Side Arm FI07650