Support materials only that illustrate some possible contexts for exploring Science as a Human Endeavour concepts in relation to Science Understanding content.
The level of alcohol in the body can be measured by testing breath or blood alcohol concentrations (ACSCH085). These analysis techniques rely on redox reactions. Police first used breath testing for alcohol in the 1940s. Currently, a range of other detection methods are available to police, and commercially to drivers who are now able to test themselves before driving. Some meters use infrared spectroscopy to determine the amount of alcohol present, which can be converted to blood alcohol concentration (BAC). Electrochemical cells form the basis of ‘alcosensors’ which can also be used to measure BAC. These cells work by recording the electrical potential produced by the oxidation of the ethanol at platinum electrodes. Although science can provide information about the effect of alcohol on our bodies in relation to the ability to drive, decisions about ‘safe’ levels of BAC for driving (including those used to write legislation) take into account other factors, such as the experience of the driver, and can vary from country to country (ACSCH086).
Redox reactions that occur spontaneously can be used as a source of electrical energy. These include wet cells (such as car batteries), dry cells, and alkaline batteries. Fuel cells are electrochemical cells that use up a ‘fuel’, such as hydrogen. Fuel cells were first demonstrated in the 1840s, but were not commercially available until the late twentieth century. Currently, small fuel cells are designed for laptop computers and other portable electronic devices; larger fuel cells are used to provide backup power for hospitals; and wastewater treatment plants and landfills make use of fuel cells to capture and convert the methane gas they produce into methane (ACSCH088). Fuel cells are a potential lower-emission alternative to the internal combustion engine and are already being used to power buses, boats, trains and cars (ACSCH088). International organisations such as the International Partnership for Hydrogen and Fuel Cells in the Economy (IPHE) have been created to foster international cooperation on research and development, common codes and standards, and information sharing on infrastructure development (ACSCH087).
Electrochemistry has a wide range of uses, ranging from industrial scale metal extraction to personal cosmetic treatments. A new application has been in the treatment of mineral rich bore water. New Zealand scientists have trialled a system that uses electrochemistry to remove the iron and manganese ions present in bore water, which currently make the water undrinkable. An electric current converts chloride ions to chlorine, which then oxidises and precipitates out the metal contaminants, as well as disinfecting the water. The electric current passing through the water also dramatically increased the effectiveness of the chlorine in killing organisms in the water. The process requires minimal current and can be provided by a 12-volt car battery, which makes it a cheap and relatively ‘low tech’ solution suitable for use in rural areas of developing countries (ACSCH087).