2 - Making & Improving Products
Scientists seek to make new products from naturally occurring starting materials such as metals, rocks and minerals by physical or chemical change. These products affect our quality of life and wellbeing.
When developing and making new products scientists have to be concerned about the effect of doing so on the environment.
2.1 Uses of electroplating
Candidates need to understand that:
Many household objects are made of metals that corrode in the presence of water and air. Electroplaters use their knowledge of the reactivity of metals to ensure that our property lasts as long as possible and is suitable for purpose. Electrolysis is used to electroplate some metals. The electroplating industry is concerned about the risks involved in the electroplating process because many of the materials used are hazardous.
Candidates need to:
1. Give reasons for electroplating metals (prevention of corrosion, decoration).
2. Name some household objects that are electroplated to prevent corrosion.
3. Describe the process of electroplating as the application of a metal coating to a metallic or conducting surface by electrolysis.
4. Know that electrolysis involves the movement of charged particles in an electrolyte.
5. Know that the cathode is the negative electrode and the anode is the positive electrode in an electrolysis cell.
6. Know that the article to be electroplated is made the cathode, and immersed in an aqueous solution containing ions of the required metal. The anode is usually a bar of the metal used for plating. During electrolysis metal is deposited on the article as metal from the anode goes into solution.
7. Understand that charged particles are called ions and that ions are atoms which have either lost or gained an electron.
8. HT only: be able to complete simple equations to show the process at the cathode and anode:
(a) Mn+ + ne– ➞ M
(b) M ➞ Mn+ + ne–
9. Explain why nickel jewellery is electroplated with precious metals (prevention of allergies or for decoration).
Within this context, candidates should be able to use scientific data and evidence to discuss, evaluate or suggest implications of the following:
■ the potential risks to employees in the electroplating industry
■ the suitability of different metals for electroplating items
■ knowledge of charged particles to explain the electroplating of metal objects.
2.2 Developing new products
Candidates need to understand that:
Scientists are constantly seeking alternative products, especially in industry where being at the forefront of technology means commercial success. Materials scientists study how things are put together (including their atomic structure) and their chemical and physical properties. They use this information to create new materials and products. They look at what they require from materials and then alter the materials to make them better suited to their job in both the home and the wider world.
Candidates need to:
1. Give examples of new products and suggest uses for them:
(a) smart (self-healing) paints – a coating that heals its own scratches when exposed to sunlight
(b) superconductors – substances whose resistance becomes almost zero at low temperatures, which reduces energy losses
(c) smart materials – substances that are able to change their properties in response to the environment
(d) chromic materials – thermochromic, photochromic – materials that change their colour according to changes in temperature and light intensity.
Within this context, candidates should be able to use scientific data and evidence to discuss, evaluate or suggest implications of the following:
■ the advantages and disadvantages of modern products compared with traditional products.
2.3 Selective breeding and genetic engineering
Candidates need to understand that:
The human population is increasing rapidly. This has had implications for feeding all of the people. Agricultural scientists have worked to produce animals and crops with favourable characteristics in order to produce more food for the increased population.
Some people believe that the risks connected with selective breeding such as ‘inbreeding’ and the development of unfavourable characteristics are a disadvantage.
Biotechnologists have developed plant tissue culture (micropropagation), which allows the rapid production of many genetically identical plants that may be used for food. They have also developed techniques that allow culture of animal and human organs.
Geneticists are also using their techniques to help couples with fertility problems or to create ‘designer babies’, and for gene replacement therapy.
Candidates need to:
1. Explain how selective breeding of plants and animals involves selecting the parents with desired characteristics, crossing them, selecting from their offspring, and then repeating the process over several generations.
2. Understand that cloning techniques involve laboratory processes to produce offspring that are genetically identical to the donor parent.
3. Explain how genetic engineering involves the transfer of ‘foreign’ genes into the cells of animals or plants at an early stage in their development so that they develop with desired characteristics.
4. Describe how human insulin is produced using genetically modified bacteria.
Within this context, candidates should be able to use scientific data and evidence to discuss, evaluate or suggest implications of the following:
■ the economic, social and ethical issues concerning genetic engineering, genetically modified foods and ‘designer babies’
■ the ethics of genetic engineering compared to selective breeding
■ the ethics of gene replacement therapy
■ examples of risks associated with selective breeding and genetic engineering.
Suggestions for practical work that could be used to support Theme 2
It is the responsibility of the centre to be aware of the health and safety implications of any practical work, and to ensure that risk assessments for practicals are carried out.
■ Grow new plants from tissue cultures.
■ Electrolysis of copper sulfate solution using copper electrodes.
■ Investigate the factors that affect electrolysis of copper sulfate/ electroplating of copper.
■ Investigate smart materials, eg memory wire, pressure-sensitive resistance film.
■ Calibrate a chromic strip to be used as a forehead thermometer.
