An undergraduate teaching initiative to demonstrate the complexity and range of issues typically encountered in modern industrial chemistry

Abstract

In 1997 the Chemistry Department at the University of Glasgow introduced a new initiative into its undergraduate teaching programme. Two exercises were developed that require the students to operate in small groups and to work through exercises that are representative of issues in contemporary industrial chemistry using a problem-based learning format. These modules, termed interactive teaching units, aim to demonstrate the number of factors, often disparate, that contribute to the implementation of successful and sustainable industrial chemical processes. The units are a vehicle for presenting applied chemistry, and also introduce the economic and environmental issues affecting an overall business area. Although these units do not specifically target the concepts of green chemistry, they do enhance student awareness of the principles that underpin the discipline. This report provides an overview of this initiative and briefly outlines the methodology adopted.

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Green Context

Chemistry undergraduate students are often thought to lack an appreciation of the role of chemistry in society and an awareness of the role of chemical industry. The increasing importance of explaining the value of chemistry in modern society and demonstrating how it can fit into a sustainable future makes it essential that we make our students more aware of these issues. This paper describes how one major Chemistry Department tackled this by developing new problem-solving, group-based exercises to communicate the ′chemical message.′ The material is based on the topical and environmentally important issues of CFC replacement for refrigeration and the industrial scale manufacture of chlorine.

JHC

1. Introduction

In 1996 a review of the undergraduate teaching programme in chemistry at the University of Glasgow indicated a poor understanding amongst our first and second year undergraduate classes of the role of chemistry in society and how chemistry provides the materials required by a modern competitive economy. In particular, the students appeared to have little awareness of the role of the chemical industry. We wished to focus their attention with the following type of questions. Why is it there? Whom does it serve? Who drives the demand for its products? Worryingly, few of our students could produce reasonable and justified answers to these questions. In addition, it was recognised that chemistry was poorly represented in the media, with the majority of articles which featured chemistry tending to concentrate on negative environmental or hazardous issues. Against this background, we decided to consider ways of informing and stimulating our students to question certain aspects of this biased representation of the chemical industry. This report outlines how the Department of Chemistry decided to tackle this discrepancy and describes some of the material developed and introduced into our undergraduate teaching programme to communicate the ‘chemical message’.

About this time, the Faculty of Medicine and the Institute of Biological and Life Sciences at the University of Glasgow had instigated a number of new courses based around Problem Based Learning.¹ Student evaluation showed these courses to be popular so it was decided to investigate the effectiveness and viability of this method for our initiative. Simultaneously, the Green Chemistry movement was emerging as a serious force in global chemistry.^2–5 Since green chemistry relates to sustainable processes, we intended this theme, along with the accompanying chemical, economic, legislative and environmental facts, to be the major issue in any material that we produced.

2. Aims

The following aims were identified: (1) To increase student awareness of the range of issues chemists typically encounter outside a university environment. (2) To emphasise the vocational nature of chemistry. (3) To develop new teaching units that will enhance student awareness of large-scale sustainable chemical processes. This aim is particularly relevant to the need for teaching material that illustrates the concepts of green chemistry. (4) To encourage student communication skills (small group interactions, oral presentations, written reports, etc.). (5) To introduce a new mode of teaching that offers diversification in the student learning experience.

3. Methodology and selection of material

We elected to adopt the problem based learning (PBL) approach successively implemented in other departments within the University of Glasgow.¹ We approached the University Teaching and Learning Service (TLS), who provided valuable advice on how to set about structuring such courses. Adopting the TLS format, which emphasises the importance of small groups, we chose to name our exercise Interactive Teaching Units (ITUs).

Several factors influenced the way the new materials were designed. For the kinds of aims in mind, educational research had indicated the nature of approach which was important.^6–10 There were many interactive teaching units already available for school chemistry,^11–13 as well as in biology at university level.¹ All used the process of interaction which has been described as internal mental interaction with new materials, ideas and concepts¹⁴ and many involved high levels of interaction between students as they discussed and argued their way forward in solving a problem. Indeed, the solving of problems was a common feature of the units. In this, students usually worked in small groups to use their knowledge of chemistry (or whatever discipline was involved) to reach answers to problems which often had major social, environmental or economic implications.

The Interactive Teaching Unit has been described as a ‘syllabus based, free-standing teaching resource which allows students to be involved in active learning by means of role play, decision taking and problem solving and seeks to simulate the kinds of experiences that they might face in the workplace or the wider world’.¹⁵

Overall, much of the material available was designed for schools, was dated or was too specific for our purposes. We required materials for the 1997–98 programme and the decision was taken to develop new materials rather than attempt to adapt other materials. Since then, some new materials have been developed elsewhere.^16,17 Our aim was that our materials should have an industrial dimension and demonstrate the importance of the chemical industry and chemists in contemporary society.

Although our intention was to feature large-scale industrial processes, initially we had no particular process in mind. After discussions within the Department of Chemistry’s Industrial Liaison Committee, ICI Chemicals & Polymers Limited¹⁸ supported our plans and Dr Neil Winterton (ICI Senior Research Associate, now at the University of Liverpool) agreed to help with validating any material we might produce. A major part of ICI Chemicals & Polymer Limited’s business at that time was halogen-based and so we decided to concentrate on this area of industrial chemistry. Chlorine chemistry was ultimately selected as it involves high volumes of potentially hazardous materials that are used in a wide variety of products. Safe and economic processes for handling chlorine are at the heart of green chemistry.

The last major parameter that needed defining was which undergraduate class should we target? We decided to concentrate on our 2nd year class (approximately equivalent to a 1st year class in the English university system), as it is this year where the students formally elect which honours degree course they will follow. Our 2nd year class size comprises approximately 200 students, which would mean committing substantial staff resource to run any units and maintain small class sizes. Nevertheless, the initiative was endorsed by the Chemistry Department and the commitment acknowledged. Each ITU operates over 4 days allowing the class to be split up into groups of approximately 48. This is then further divided into 4 tutorial groups of 12 students. Each group is led by a tutor, who is a member of the academic staff. This arrangement is staff intensive but evaluation reveals the students benefit and appreciate the opportunity to interact in a relatively informal manner, i.e. compared with lectures and practical classes, with faculty members.

After substantial investment in time and energy, two ITUs were produced. The first (ITU1), entitled ‘The Age of Refrigeration’, examines the issues associated with the replacement of chlorofluorocarbon (CFC) refrigerants. This unit aims to expose the students to relevant issues in chemistry, economics, environmental issues, politics and legislation that surround the topic. In order to illustrate the dynamic nature of the chemical industry, the issues are considered over a period of time, viz. 1970, 1987 and 1999. The second module (ITU2) is entitled ‘Mercury, Membrane or Diaphragm’ and examines the concept of producing chlorine, sodium hydroxide and hydrogen on an industrial scale. As such, it represents an exercise in applied electrochemistry. Comparable issues to those considered in ITU1 are examined but, in addition, emphasis is given to issues of safety, chemical engineering and concepts of scale. The specifics of both units are described individually in Section 4. The units were successfully trialed in 1997 and, after some tweaking, were formally introduced in to our undergraduate teaching programme in 1998.

Finally, it is worthwhile to comment on the expertise necessary to bring these units to a satisfactory standard. Firstly, the structuring, timing and composition of the units is crucial. TLS’s experience in class dynamics was vital to maintain student interest and activity levels over the 3 h duration of which both exercises run. Secondly, in 1997 a large quantity of literature on the topics selected was not readily accessible in the public domain, with much of the wisdom retained within industry. This was particularly true in the case of the refrigerant unit (ITU1), although comprehensive review papers on this topic have just recently been published.^19,20 Acquisition of up to date data and validation of the whole exercise by experts in two very specific areas of chemistry were essential to produce units that were genuinely representative of the industrial scenario. Without the assistance of Dr Neil Winterton and his colleagues at ICI Chemicals & Polymers Ltd., the range of issues covered within the units would have been substantially restricted and, consequently, less relevant. Finally, it is noted that both the story about CFC replacements and chlorine production by electrolysis have their own dynamics and information current when the units were produced (1996–1998) can become obsolete very quickly. Nevertheless, the general principles remain valid and our students can learn and benefit from participation in such an exercise. The following section describes the Units as they currently stand. Future up-grades of the facts and figures will always be required.

4. Course content

4.1 ITU1. The age of refrigeration

This unit examines issues in the replacement of CFC refrigerants as viewed from different periods of time: 1970, 1987 and 1997. The unit starts by introducing the general concepts of refrigeration. Post-war, the market for refrigeration, and thereby refrigerants, has grown dramatically. Refrigeration is now a part of everyday modern life and represents a diverse market; ranging from relatively small scale domestic refrigerators and air conditioners to large scale industrial units.

Refrigeration is described using the classical thermodynamic approach,²¹ which accounts for the transfer of heat from a cold compartment to hotter surroundings utilising the latent heat of vapourisation of a refrigerant. The refrigerant is moved about the system by means of a compressor. Fig. 1 schematically represents the general process. The refrigeration process can be described by eqn. (1)

where w represents the work expended, m is the mass of refrigerant, ΔH_vap is the enthalpy of vapourisation of the refrigerant, T_h is the temperature of the hot surroundings of the refrigerator and T_c is the temperature of the refrigerator cold compartment. The cyclic nature of the process is described and the pivotal requirement for condensation of the refrigerant from the vapour phase is emphasised.

Fig. 1 Schematic diagram of a refrigeration unit: T_c and T_h, respectively, represent the temperatures of the cold compartment and the surroundings; q_h is the heat passed to the surroundings, which is the sum of q_c, the heat taken from the cold compartment, and w, the amount of work involved. The figure is adapted from ref. 21.

1970. The students are then introduced to Table 1, which outlines some physical values of a range of potential refrigerants. The refrigerants selected are representative of the following subsets: chlorofluorocarbons, hydrochlorofluorocarbons, hydrofluorocarbons, inorganics and hydrocarbons. The students operating in groups of 12 are encouraged by their tutor to define and explain the importance of the enthalpy of vapourisation and to discuss the effects of hydrogen bonding on boiling points. This dataset also provides the opportunity to describe Trouton’s Rule,²² which rationalises comparable enthalpies of vapourisation as verification that the liquid → gas transition is dominated by a large entropy factor.

Table 1 Physical properties of a range of potential refrigerants

Refrigerant	Molecular weight	Enthalpy of vapourization, ΔHvap/kJ mol^−1	Bp/°C	Mp/°C	Critical temp./°C
CCl2F2	121	20.0	−29.8	−155.0	112
CHClF2	86.5	20.2	−40.8	−160.0	96
CF3CH2F	102	22.1	−22.2	−108.0	101
NH3	17	23.2	−33.4	−77.7	132
H2O	18	40.4	100.0	0.0	374
C4H10 (isobutane)	58	21.0	−11.7	−159.7	135
CO2	44	25.1	−78.5	−56.6	31

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Table 2 provides further information on the flammability, toxicity and relative cost of these possible refrigerants. In small working groups of four students, the concept of critical temperature (T_c) and likely operational temperature ranges are considered. The critical temperature is the temperature above which a gas cannot be liquified by pressure alone. For temperatures in excess of T_c, there is no longer any distinction between liquid and vapour phases, i.e. only a (dense) gas phase exists. This parameter, specified for all candidate refrigerants in Table 1, excludes the use of CO₂ as a potential refrigerant under conventional operating conditions because of its inability to be converted back to a liquid from a vapour as part of the refrigeration cycle. The students also need to realise that complete toxicological information for some compounds (e.g. CF₃CH₂F) was not available in 1970.

Table 2 Assessment of the flammability, toxicity and relative cost of a range of potential refrigerants using information available in 1970

Refrigerant	Flammable?	Toxic?^a	Relative cost (1970 values)
a The greater the number of crosses, the lower the toxicity. b At the purity levels required. c Burns only in the presence of a supply of oxygen. d The powerful smell of ammonia makes poisoning unlikely. e Slight anaesthetic properties.
CCl2F2	No	+++++	Fairly cheap
CHClF2	No	+++++	Moderate
CF3CH2F	No	Unknown	Unknown
NH3	Yes^c	+^d	Fairly cheap
H2O	No	+++++	Negligible
C4H10 (isobutane)	Yes	+++^e	Expensive^b
CO2	No	+++++	Negligible

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Each student is then asked to decide which compounds should be selected as suitable refrigerants. Without exception, they select CCl₂F₂ (a chlorofluorocarbon) as their first choice and CHClF₂ (a hydrochloroflurocarbon) as their second choice. This outcome is totally consistent with the refrigerants selected by industry from ca. 1944–1980.²⁰

1987. The students are made aware of the pioneering paper by Rowland and Molina published in 1974²³ that suggested that chlorofluorocarbons (CFCs) are broken down by UV light in the stratosphere. In the upper atmosphere, ozone is normally in equilibrium with oxygen and oxygen radicals (eqn. (2)):

O₃ + hν → O₂ + O˙ (2)

However CFCs can interact with stratospheric ozone by the following mechanism (eqns. (3)–(6)):^24a,25

CCl₂F₂ → CClF₂˙ + Cl˙ (3)

Cl˙ + O₃ → ClO˙ + O₂ (4)

ClO˙ + O˙ → Cl˙ + O₂ (5)

Overall reaction O₃ + O˙ → 2O₂ (6)

Hence, ozone is catalytically destroyed by chlorine atoms formed in the photolytic decomposition of CFCs. We acknowledge that this homogeneous mechanism is an oversimplification and a heterogeneous reaction is now the preferred mechanism,^19,26 but our 2nd year class have no experience of heterogeneous kinetics and the simpler scheme seems more appropriate for this level of study. The importance of UV absorption by ozone and the consequences for life processes are stressed.

Students are next informed about the Montreal Protocol^19,20,27,28 which aims to reduce ozone depleting chemicals (e.g. CFCs) in developing countries by 50% by the year 2000. Annual global CFC production figures are estimated at ca. 1.11 × 10⁶ tonnes, with sales of approximately £300 million per year. Thus CFC production represents a large and expanding market, for which replacement refrigerants or alternative refrigeration methodologies need to be found, quickly.

The gravity of the position is further heightened by informing the students about greenhouse gases and the topic of global warming.^24b,29Table 3 quantifies the ozone depletion potential and the global warming potential of some candidate refrigerants.^19,20

Table 3 Ozone Depletion Potential (ODP) and Global Warming Potential (GWP) for a range of candidate refrigerants.^19,20 The ODP values are related to CCl₃F (CFC-11), which is assigned a value of 1.0. The GWP values are relative to CO₂ over 100 years

Refrigerant	Ozone Depletion Potential (ODP)	Global Warming Potential (GWP)
CCl2F2 (CFC-12)	1.0	8500
CHClF2 (HCFC-22)	0.06	1700
CF3CH2 (HFC-134a)	0.0	1300
NH3	0.0	Insignificant
C4H10 (isobutane)	0.0	Insignificant

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The alternatives to CFCs can be divided into four groups: (a) hydrofluorocarbons (HFCs), (b) hydrochlorofluorocarbons (HCFCs), (c) inorganic substances and (d) hydrocarbons. The tutor then divides up his group of 12 students into three sub-groups of four students who are asked to role play the positions of three distinct parties: (i) existing CFC manufacturers, (ii) manufacturers of refrigeration equipment and (iii) environmental monitoring and protection agencies. The tutor adopts the role of Government. The three sub-groups are supplied with a two page briefing document that represents the stance/perspective of that particular interest group. The groups are then asked to decide which replacement refrigerants should be adopted, for what reasons and to propose an implementation strategy. They make short oral presentations. An example of the questions to be addressed by one of the groups, the CFC manufacturers, is presented below.

What would be the best replacement refrigerant? Who should pay for the changes? How much is your sub-group prepared to pay/contribute to the proposed changes? What assistance do you require from Governmental organisations to manage/support the proposed changes? Broadly identify the customers that you service and your financial base. Are there any alliances that you could consider forming?

The tutor, representing Government, then guides the tutorial group in a discussion where they try to agree an overall solution. A spokesperson is elected and their conclusions documented. The whole class of 48 students is then reunited and the outcomes from the four tutorial groups compared.

1999. The ITU terminates with a plenary session in which a lecturer summarizes the position from a contemporary perspective. The scientific significance of the topic is brought home to the students by the award of the 1995 Nobel prize in Chemistry to Rowland and Molina. They are up-dated on the levels of CFC production in Europe and America and the different political influences in these regions. Recent trends towards hydrocarbon refrigerants³⁰ are discussed but the hydrofluorocarbon CF₃CH₂F (HFC-134a) is identified as the major replacement for CFCs.^19,20 Industrial based organizations such as the Program for Alternative Fluorocarbon Toxicity Testing (PAFT) have published reliable data establishing the low toxicity of HFC-134a,^20,31,32 thereby giving it the green light for general usage.

Methods for the production of HFC-134a are considered, but the ICI route (eqn. (7)) is highlighted:²⁰

The importance for a suitable catalyst in the final step, so that the process can operate at an acceptable rate, is emphasized. Viability of the process is ensured by extensive recycling of organics and HF. ICI were awarded the MacRobert Engineering Award in 1993 in recognition of developing and commissioning an industrial process to manufacture HFC-134a. The class are made aware that successful achievement of such a substantial development project in only five years is exceptional and further emphasizes the highly competitive nature of the refrigerant manufacturing business.

The final topic to be considered is the concept of Total Equivalent Warming Impact (TEWI) applied to refrigeration and, in particular, the relative contribution of the actual refrigerant to global warming.³³ A domestic refrigerator is chosen as an example and the TEWI estimated. A direct contribution comes from the potential emission of (i) the refrigerant and (ii) the blowing agent for the foam insulation used in the construction of the refrigerator. Both of these materials can operate as greenhouse gases. However, more relevantly, there is a substantial indirect contribution to the TEWI that relates to the energy expenditure on operating a refrigerator continuously for approximately 10 years. Combustion of fossil fuels is still a major route for the generation of electricity. This process produces CO₂, which is itself a potent greenhouse gas. The atmospheric half-life of CO₂ is approximately 500 years, so it is necessary to consider at least a 500 year time span to calculate a TEWI.³³ (We acknowledge that 100 year timespans are the accepted timescale under the Kyoto Protocol and are the standard used to calculate TEWI but we wished to illustrate the point that materials with long atmospheric lifetimes can have an effect over substantial timescales.) Fig. 2 illustrates the different contributions to the overall TEWI over this period.³³ The term radiative forcing is used as a measure of the extent of global warming.³⁴ Clearly, the indirect production of CO₂ is the major contributor to global warming. The use of HCFC-141b as a blowing agent for the refrigerator foam insulation makes the second largest contribution and, if HFC-134a is selected as the refrigerant, then this compound makes a negligible impact on the TEWI. Furthermore, in addition to the minimal magnitude of the effect of the actual refrigerant, it is noted that whereas the blowing agent and refrigerant are completely accounted for within 100 years, the CO₂ produced will continue to contribute to global warming for a further 400 years and beyond. Unfortunately, we cannot use all the amenities available to us at no cost to the environment. However, we can do our best to minimize their impact with an innovative chemical industry playing a vital role.

Fig. 2 Radiative forcing of greenhouse gases (in kg of CO₂ equivalents) from a domestic refrigerator/freezer. The lower lightly shaded area represents the CO₂ contribution. The contribution from the foam blowing agent (HCFC-141b) is designated by the hatched lines. The negligible contribution from the refrigerant (HFC-134a) is signified by the thickness of the line that resides on top of the hatched and shaded areas. The figure is adapted from ref. 34.

Collectively, this exercise aims to demonstrate the complexity that is common in modern industrial chemistry. Moreover, through example, it attempts to illustrate the fact that the successful implementation of new manufacturing procedures for an ever changing market place is a demanding task, in which chemists play an important and critical role.

In order to encourage active participation, the exercise is formally assessed and the students are asked to write a short essay on a topic related to the exercise. An example of a recent assignment is: ‘The Minister for the Environment has been asked in the House of Commons to supply the Government’s recommendation for which refrigerants should be used in the next decade. You are a scientific civil servant. Prepare a 1 page (ca. 500 word) briefing document for your Minister.’ The essays are marked by the tutors and the ITU assessment comprises 5% of the overall course mark. Awarding a relatively high mark ensures that the students take the exercise seriously.

4.2 ITU2. Mercury, membrane or diaphragm

This ITU examines issues relevant to the chlor-alkali industry and concentrates on the industrial scale manufacture of chlorine, sodium chloride and hydrogen. An information pack on ‘Green Chlorine’, prepared by the Chemical Industry Education Centre at the University of York,³⁵ was available but this was targeted at 13–16 year olds and was deemed not to be suitable for our undergraduate classes.

The industrial process is carried out by electrolysis of rock salt and is governed by eqn (8).

2NaCl + 2H₂O → Cl₂(g) + 2NaOH(aq) + H₂(g) (8)

Chlorine demand is traditionally the factor which governs the chlor-alkali industry.^36,37 However, sodium hydroxide also plays an important part. Demand dictates that the price of these commodities are rarely constant, causing substantial variations in the profitability of the overall process. For example, during the 1980s the lowest price for sodium hydroxide was $40 per tonne and the highest price $500 per tonne. And over a comparable period, wide variations in the chlorine price were also observed.³⁸ Given that chlorine and sodium hydroxide prices are rarely in phase,³⁹ it is a difficult task to manage the process in such a way that the overall business is economic.

Within tutorial groups comprising a maximum of 12 persons, the students participate in exercises that demonstrate the size of the markets and the market outlets for these products.^36,37,39 The students are generally unaware that, for example, the manufacture of PVC that is used in the guttering on their house/flat requires a source of chlorine, or that paper processing requires substantial quantities of sodium hydroxide. The class are reminded of the general concepts of electrolysis, then they are made aware of the problem with electrolysis applied to this particular chemical system. Specifically, because of the following reactions [eqns. (9–12)], the products must not be allowed to mix.³⁶

Cl₂ + OH⁻ → Cl⁻ + HOCl (9)

HOCl → H⁺ + OCl⁻ (10)

2HOCl + OCl⁻ → ClO₃⁻ + 2Cl⁻ + 2H⁺ (11)

4OH⁻ → O₂ + 2H₂O + 4e⁻ (12)

Electrolysis in a simple one-pot vessel will lead to reaction of chlorine with sodium hydroxide to give unwanted sodium hypochlorite (NaClO), sodium chlorate (NaClO₃) and oxygen as bi-products. In addition, the function of the cell design is also to keep hydrogen and chlorine gases separate because they can combine explosively.

The tutorial group is then split into three sub-groups which are asked to adopt the role of a process design team that considers the effectiveness of one of three types of electrochemical cell: a mercury cell, a membrane cell, or a diaphragm cell.^36,37,39,40 Each sub-group comprises four students. The sub-groups are provided with information on the respective cells in three stages. The introductory information is just sufficient for them to be able to work out how the cell might actually operate. The last batch of information effectively explains the complete operational characteristics of their particular cell. This format gives the participants experience of attempting to effect designs with limited information, a not untypical situation. Using the adage—‘you don’t fully understand something until you can explain it to others’ the students interact in their sub-groups to give a presentation to the tutorial group as to how their cell operates. Fig. 3 shows an example of some of the introductory information pertaining to the mercury cell and Fig. 4 shows the completed diagram given to the sub-groups towards the end of the design session. The students are provided with Fig. 3 as an overhead projector acetate to assist them in their initial presentation.

Fig. 3 Initial schematic diagram of a mercury electrochemical cell given to assist the design team to understand how the equipment functions. They are also presented with the accompanying series of chemical equations, which they need to assign to the relevant parts of the apparatus.

Fig. 4 Completed schematic diagram of a mercury electrochemical cell presented to students at the end of the session when the design teams are asked to understand how their particular cells operate. They are also provided with the electrochemical equations.

Guided by the tutor, the three sub-groups discuss which electrochemical cell should be selected. They are provided with information on energy costs and typical purity levels associated with the three types of cell. The three sub-groups then debate amongst themselves the advantages/disadvantages of ‘their’ design and present the answers in another oral presentation. This unit therefore asks the students to consider issues in applied electrochemistry, with a process engineering perspective. The tutorial group elect a spokesperson who documents their conclusions.

In the plenary session the whole class of ca. 48 students is reunited. The tutorial group representatives summarize the conclusions from the four tutorial groups. The lead lecturer then uses slides and a video to show the students the mercury, diaphragm and membrane cells that operate at INEOS Chlor’s plants at Runcorn and Lostock. The students get to appreciate the full scale of the operation and its associated power requirements at this stage. The significance of environmental issues are shown to be increasingly important, by reference to incidents such as that which occurred in Minamata Bay, Japan in 1965 where mercury contamination led to severe health problems in the local population.³⁶ Geo-political and economic implications of such events are considered and discussed. The introduction of the coated titanium anode (aka dimensionally stable anode) in the 1970s is described and recognized as a major milestone in the chlor-alkali industry.^36,37,41 As with ITU1, coursework is assigned. Generally, this requires the students to explain how their specified cell operates and to compare their cell against the alternatives.

5. Student evaluation

At the end of each ITU session the students are asked to evaluate the course. Representative results from evaluation of ITU1 run over the years 1998, 1999 and 2000 are shown in Table 4. Consistently high evaluations are received every year, which is felt justifies the considerable staff resource allocated to the running of these units. The ITU topics have a modest overlap to material the students are exposed to in lectures, which means that they have some connectivity to the topics being examined. They also seem to enjoy the applied aspect of the exercise that examines practical and associated elements of a complex dynamic. The significant ‘no’ response to the question, ‘would you like to see more ITUs as part of your degree programme?’ (Table 4) was unexpected and contrasted with the overall positive student response. However, further questioning revealed the origin of this negative response was the inherent reluctance of some of our students to make oral presentations to even quite small audiences. This is understandable but it is important that we continue to provide our students with the opportunity to develop their presentational skills. To further this aim, more opportunities for group presentations have recently been introduced into the overall undergraduate teaching programme, and it is hoped that increased familiarity with the requirement to give modest oral presentations will minimize the trauma experienced by a proportion of the students.

Table 4 Examples of student evaluation results for ITU1 (The Age of Refrigeration). The sample relates to the response received from a total of 552 students spread over 12 sessions run in 1998 (4), 1999 (4) and 2000 (4). The specific response as a percentage of the full sample for each question is presented in parentheses

	Very poor	Poor	Average	Good	Very good
1. Grade the overall effectiveness of the ITU to present the issues perti nent to the use of refrigerants.	1	2	42	354	155
	(0.2%)	(0.4%)	(7.5%)	(63.9%)	(28.0%)
2. Did you enjoy taking part in the exercise	Yes		No
	521		31
	(94.4%)		(5.6%)
3. Would you like to see more ITUs as part of your degree performance?	Yes		No
	415		133
	(75.7%)		(24.3%)

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6. Summary

The experience from introducing the two interactive teaching units into our 2nd year chemistry course at the University of Glasgow can be summarized by the following points.

The ITUs diversify the student learning experience and provide the opportunity for improvements in communication skills.

The ITUs provide an insight into industrial chemistry and the complexity of problems typically encountered in an industrial scenario.

The ITUs improve student understanding of the role of chemistry and the chemical industry in society.

The industrial support proved to be extremely valuable. Any exercise that attempts to present a perspective of activities outside the university environment will always benefit from feedback from experts on the field.

The Interactive Teaching Units (ITUs) are a stimulating medium to enhance student awareness of environmentally sustainable products and processes, i.e. green chemistry.

Acknowledgements

The substantial assistance of ICI Chemicals & Polymers Limited (now INEOS Chlor Ltd. and INEOS Fluor Ltd.)¹⁸ is gratefully acknowledged. Dr Neil Winterton (ICI, now at the University of Liverpool) coordinated the overall ICI contribution. Dr Dick Powell (ICI, now at the University of Manchester Institute of Science and Technology) and Mr Archie McCulloch (ICI, now at the University of Bristol) provided technical assistance relating to new refrigerants and Dr Mottram Couper (ICI, now at INEOS Chlor Ltd.) contributed to the electrochemistry module. INEOS Chlor Ltd. and INEOS Fluor Ltd. are thanked for also supporting this educational initiative. Dr Phil Landon acknowledges financial support from the Scottish Higher Education Funding Council. ICI are thanked for the provision of a Lectureship in Heterogeneous Catalysis (DL). The humour, wisdom and patience of past and present members of the ITU Tutorial Team (Dr John Carnduff, Dr John Dymond, Dr Adrian Lapthorn, Dr David McComb, Dr Ken Muir, Dr Marie-Claire Parker, Dr David Procter, Dr David Rycroft and Dr Diane Stirling) are gratefully acknowledged. Without their persistence and strength these units would have died in the trial stage. Mrs Kirsty Letton (Teaching and Learning Service, University of Glasgow) assisted with the initial drafting of both units. Mrs Lesley Bell and Mr Bob Munro (Department of Chemistry) are thanked for careful preparation of the teaching material.

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