Concerns over the Image of Chemistry
Green Chemistry Principles should be implicit in teaching and practical work in the first place, rather than relying on examination specifications.
Environmental concerns over the use, emissions and disposal of chemicals have always been important to CLEAPSS. Usually, our advice refers to the UK COSHH Regulation which require users to always use the least hazardous chemicals (amongst other control measures) in a chemical process. In general, a chemical which is less dangerous to our health, is also less dangerous to the environment. Naturally we also follow other national and international guidance, such as the Montreal Protocol which limits the use of organohalogens.
CLEAPSS has pioneered new approaches to many traditional chemistry experiments, eg, the use of a measured dose of copper oxide (just an excess) when making copper sulfate crystals (PP027 Making copper sulfate crystals) or reducing sulfur dioxide emissions when reacting thiosulfate ions with acid (L195 Safer chemicals, safer reactions). Remember too, that in the world of chemistry, the chemicals used in schools are a small fraction of those used in industry and domestically.
There is a groundswell of concern at present, particularly amongst students, about the state of the planet. They, and some teachers, technicians and parents, will ask “what about the chemicals in the science department?” Risk assessment, published by CLEAPSS and others, include not just the procedure, but also environmental issues which might occur on disposal of the residues.
Green chemistry has entered our A level chemistry schemes in the past, and then disappeared. In the USA they remain important in chemistry studies. The guiding light is Dr John Warner https://www.beyondbenign.org. His website provides free material for K-12 students and also lists 12 Principles for Green Chemistry. These are listed in the table below. Those written in green text have immediate relevance to school chemistry, those written brown text are more relevant to industry and research.
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Applicable in school chemistry
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More applicable to industry and research
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The 12 Principles are widely accepted by industry and government organisations in the US and UK. However, they are not generally found in examination courses where the exam requires simple, straightforward answers. Interestingly “Atom Economy” is the only principle regularly quoted in specifications, presumably because it requires a calculation. Responses to other ‘environmental’ questions give obvious (and simplistic) answers, such as: reuse by-products, find more active heterogeneous catalysts, and manage waste better, etc. Green Chemistry Principles should be implicit in teaching and practical work in the first place, rather than relying on examination specifications.
The impact of this thinking is already evident in the work of European Chemical Agency (EChA) which looks after the EU Reach Regulations. Green Chemistry, though, remains a challenge for UK science teachers both in content and attitude. For example, chromium(VI) compounds are truly bad for the environment, and for those using them. They are beginning to become unavailable from suppliers. Schools can use what they have but since they are so hazardous, why keep on using them? A school may have 500g of potassium dichromate(VI) but only use 10g a year, so that there is 50 years of supply on the shelf. It is unlikely that such chemicals will be banned nationally, but examination boards and curriculum advisers could readily remove the need to use them from syllabuses and practical requirements.
The CLEAPSS long-term interest in microscale techniques does reflect much of our concern. It produces much less waste and is much safer to carry out. Even when substances, which have serious hazards and environmental concerns are used in schools, the exposure is significantly reduced via these techniques, so much so that expensive fume cupboards are not required (see PP059 Micro-electrolysis of copper(II) chloride solution).
It could be argued that chemistry will not be “fun” anymore with explosions, fires, sparks, smells, smoke, etc. It could, and is, argued that chemistry should not promote these possible methods of maiming, burning or poisoning people. The very image posed by ‘chemistry is fun’ is an image that cause people to say chemicals should be banned and not used in schools. Teaching and learning should be enjoyable but that can be conveyed by the teacher in many ways other than (mis)using chemicals.
Students from our schools will be required to solve the present problems on our planet, and to invent new ideas. Chemistry (and chemicals) must be in the curriculum. Electrically powered cars, sneered at by many 5 years ago, are now being seen on our roads. The challenge is better batteries and, possibly, their disposal. Plastic needs to degrade quicker, and into benign substances. Methods of targeting drugs to specific areas in the body, and therefore needing less of them, are being developed. Wind turbines were considered a waste of time 10 years ago but now contribute a significant proportion of our energy.
Closing our eyes is not the answer. We need teachers to help students better understand the detail of the issues so they stand some chance of being able to tackle them. The aim is to go beyond benign.
The impact of this thinking is already evident in the work of European Chemical Agency (EChA) which looks after the EU Reach Regulations. Green Chemistry, though, remains a challenge for UK science teachers both in content and attitude. For example, chromium(VI) compounds are truly bad for the environment, and for those using them. They are beginning to become unavailable from suppliers. Schools can use what they have but since they are so hazardous, why keep on using them? A school may have 500g of potassium dichromate(VI) but only use 10g a year, so that there is 50 years of supply on the shelf. It is unlikely that such chemicals will be banned nationally, but examination boards and curriculum advisers could readily remove the need to use them from syllabuses and practical requirements.
The CLEAPSS long-term interest in microscale techniques does reflect much of our concern. It produces much less waste and is much safer to carry out. Even when substances, which have serious hazards and environmental concerns are used in schools, the exposure is significantly reduced via these techniques, so much so that expensive fume cupboards are not required (see PP059 Micro-electrolysis of copper(II) chloride solution).
It could be argued that chemistry will not be “fun” anymore with explosions, fires, sparks, smells, smoke, etc. It could, and is, argued that chemistry should not promote these possible methods of maiming, burning or poisoning people. The very image posed by ‘chemistry is fun’ is an image that cause people to say chemicals should be banned and not used in schools. Teaching and learning should be enjoyable but that can be conveyed by the teacher in many ways other than (mis)using chemicals.
Students from our schools will be required to solve the present problems on our planet, and to invent new ideas. Chemistry (and chemicals) must be in the curriculum. Electrically powered cars, sneered at by many 5 years ago, are now being seen on our roads. The challenge is better batteries and, possibly, their disposal. Plastic needs to degrade quicker, and into benign substances. Methods of targeting drugs to specific areas in the body, and therefore needing less of them, are being developed. Wind turbines were considered a waste of time 10 years ago but now contribute a significant proportion of our energy.
Closing our eyes is not the answer. We need teachers to help students better understand the detail of the issues so they stand some chance of being able to tackle them. The aim is to go beyond benign.
Addressing single use plastic pipettes
How many washes does it take to remove chemicals other than water from a used plastic Pasteur transfer pipette?
I have been in many schools where they are just thrown away making the pipette a single use plastic. That is not a good message to send to students. If every student were to rinse their pipette at last 3 times (using the method in the video), after use and before handing them back, it would reduce the teacher or technician workload. Pie in the Sky? May be! But what happens to pipetttes if we do not begin to do this.
This would make an instructive lesson in green chemistry. It can be carried out using
However, if you have several clean but damp pipettes, suck up ethanol invert, expel and leave to dry and with a few hours they are are ready for use..Is this a good use for ethanol? For individual use it probably is.
A bulk load of wet pipettes can be left in an oven set at 50ᵒC. At higher temperatures, polythene begins to soften.
I have been in many schools where they are just thrown away making the pipette a single use plastic. That is not a good message to send to students. If every student were to rinse their pipette at last 3 times (using the method in the video), after use and before handing them back, it would reduce the teacher or technician workload. Pie in the Sky? May be! But what happens to pipetttes if we do not begin to do this.
This would make an instructive lesson in green chemistry. It can be carried out using
- colour (eg potassium manganate(VII) or dyes)
- pH (eg using an acid and an alkali and washing with water with Universal Indicator or a pH meter/paper strips)
- cation or anion analysis (looking for precipitates) and
- an ion detector (the CLEAPSS conductivity indicator whose LED should not light up in the final washings ).
However, if you have several clean but damp pipettes, suck up ethanol invert, expel and leave to dry and with a few hours they are are ready for use..Is this a good use for ethanol? For individual use it probably is.
A bulk load of wet pipettes can be left in an oven set at 50ᵒC. At higher temperatures, polythene begins to soften.
Recycling alkenes from polythene
Here is a microscale method for chemistry students which takes a small amount of polythene from a plastic pipette and attempts to reclaim the monomer, ethene. It illustrates the green issues of requiring energy, better catalysts and reaction conditions to attain better yields. This is the same equjip via which alkanes can be cracked into smaller hydroxarbonas and propan-2-o is converted to propene.