Green Chemistry
We depend on the chemical industry to make useful products for our everyday lives. Bulk chemicals are made on a large scale, often millions of tonnes per year e.g. sulphuric acid, sodium hydroxide and ethene. Other chemicals are produced on a much smaller scale e.g. drugs, food additives and liquid crystals. These processes however, produce large quantities of waste by-products which build up on the Earth’s surface or are released into the atmosphere. Government agencies monitor and regulate chemical industries in order to protect the environment and ensure the health and safety of all those associated with the production and use of chemicals.
Green Chemistry is a branch of chemistry responsible for finding ways to make industrial processes less damaging to the environment. This can be done by re-cycling resources, by reducing the by-products or finding ways to make them less harmful to the environment.
This topic provides many opportunities for student discussion and research. It will raise awareness of the processes involved in the manufacture of everyday materials and how household waste is disposed of. Most homes have re-cycling bins so this should be a familiar topic for students to explore but they may not have any awareness of what happens to the waste after it has been collected.
This list provides resources which can be used to teach about recycling, sustainability, and reducing the effects of environmental pollution.
The principles of green chemistry are outlined in Anstas and Warner (1998). Green Chemistry: Theory and Practice, Oxford University Press.
Whilst this list provides a source of information and ideas for experimental work, it is important to note that recommendations can date very quickly. Do NOT follow suggestions which conflict with current advice from CLEAPSS, SSERC or recent safety guides. eLibrary users are responsible for ensuring that any activity, including practical work, which they carry out is consistent with current regulations related to Health and Safety and that they carry an appropriate risk assessment. Further information is provided in our Health and Safety guidance
Recycling and Sustainability
You could introduce the topic of recycling by asking students what household items are recycled. All homes will have recycling wheely bins for plastics, cardboard. metal cans, food and garden waste. They could be asked what they think happens to these waste products after they are collected. They could also consider what materials are not recycled - for example, polystyrene.
They could research alternative packaging being used to reduce the need for manufacturing more of these non-biodegradable plastics. The activities in this SEP resource can be used to support students' research into the problems with plastics in the environment and ways of recycling plastics, paper and metals. There are some practical as well as research type activities and useful background information.
The Twelve Principles of Green Chemistry can also be used as an introduction to activities in this booklet.
Other examples of industrial processes that have been made greener can be found on the Greener Industry website.
Food Waste Recycling - Power from Potato Peelings
Most students will be familiar with food recycling but not many will know what happens to it after it has been collected from their wheely bins.
This article could be used as a starter activity to give students information about the processes involved in food recycling and the use that is made of it. Students could research what happens to other household waste that is recycled. A trip to a local recycling depot may be a possible enrichment activity.
Practical actvities linked to this which would be interesting for the students are Plastic from milk and Making a plastic from potato starch.
Air Quality
Students will probably be aware of the effects of carbon dioxide on the atmosphere since this is the most commonly talked about. This SATIS Revisited resource provides a structured approach for students to investigate the effects of human activity on air quality (it also highlights that some of these pollutants are from natural processes).
Students will be able to measure local air quality, the amount of pollution present and its effects on human health.
This can be followed up by using the resource Air quality monitoring which looks at the air pollution at East Midlands Airport.
This resource has a quiz that can be used as a starter activity, along with some national air pollution data.
An alternative resource which may be useful is the argument about Carbon emissions from the Economic and Social Research Council (ESRC). This could be used as an exemplar for students to show them how to write a good scientific argument.
RSC Inspirational Chemistry - resources for the modern curricula
This is a selection of practical and research activities which introduce students to the problems of our modern world - for example, use of plastics for packaging, nappies, dry cleaning and so on.
You could work through each of these activities in turn with the whole class. As an alternative you could provide each student with The Twelve Principles of Green Chemistry and dicsuss each one with the students. Students could then be asked to research a particular topic or industrial process that has been made greener and present their findings to the group. The plenary session is important when doing this type of research activity to draw together the key learning points.
Teaching points to make:
Most of the chemical industry is concerned with turning one material (the raw material) into another one that is more useful and valuable (the product). The products are divided into ‘green’ and ‘brown’ products, with the former being the desired products and the latter being the waste products.
All the designers of chemical processes want to make the maximum amount of product they can from a given raw material. Percentage yield and atom economy of processes are important measures of its efficiency.
Section 6.6.1 shows how yield can be calculated.
Another key principle of green chemistry is that processes should be designed so that the maximum amount of all the raw materials ends up in the product and a minimum amount of waste is produced. A reaction can have a high percentage yield but also make a lot of waste product. This kind of reaction has a low atom economy. Both the yield and the atom economy have to be taken into account when designing a green chemical process:
This is also explained further in Section 6.6.1.
Climate Change
This is a complete discussion activity - it provides information about how to structure a debate along with all the background information and resource sheets needed to run it. It might be useful, in advance of this activity, to have done some similar activities where students look at information from varying points of view. The use of De Bono's hats could help to do this.
A useful starter to set the scene would be one of the following practical demonstrations to show students the effect of greenhouse gases on climate change: The greenhouse effect - 1 and The greenhouse effect - 2.
Key Stage Four: Climate Change
In this activity students evaluate evidence for climate change and ways of managing its effects.
As a starter you could show a clip of a television weather report and discuss with students the use of simulations and modelling to make predictions about weather forecasts.
This resource can be used in addition to the previous resource, or as an alternative activity. If you are not using the Democs Climate Change resource mentioned previously then you may need to show the RSC greenhouse effect demonstrations as an introduction.
The activity provides the opportunity to use computer models and simulations to predict climate change.
New Cement Set to Reduce Carbon Emissions
This article can be used as a starter activity to introduce new and novel technologies. Additional information about what else is being developed can be found on the EPSRC web site.
It also demonstrates that there are many opportunities for careers in chemical industries as they develop new materials for a greener environment.
Students could be asked to research a new technology that they have a particular interest in and prepare a presentation to the rest of the group.
You may want to consider a visit to a local company or inviting a STEM Ambassador into school
Examples of chemical processes that have been made greener can be found on the Greener Industry website. These include processes associated with aluminium, ammonia, ethanoic acid, ethanol, nitric acid, nylon, poly(ethene), PVC and sulphuric acid.
