Examples in Context – Chemistry
Unit 1
Properties and structure of atoms
Models of the atom
In the early nineteenth century, Dalton proposed some fundamental properties of atoms that would
explain existing laws of chemistry. One century later, a range of experiments provided evidence that
enabled scientists to develop models of the structure of the atom. These included using radiation in
the form of X-rays and alpha particles, and the passing of particles through a magnetic field to
determine their mass (ACSCH010). Evidence from French physicist Becquerel’s discovery of
radioactivity suggested the presence of subatomic particles, and this was also a conclusion from gas
discharge experiments. British physicist J.J. Thomson was able to detect electrons, and his results,
combined with the later work of Millikan, an American experimental physicist, resulted in both the
charge and mass of electrons being calculated (ACSCH009). The British chemist Rutherford proposed
a model of the atom comprising a heavy nucleus surrounded by space in which electrons were
found, and Danish physicist Bohr’s model further described how these electrons existed in distinct
energy levels. The last of the main subatomic particles, the neutron, was discovered by the English
physicist Chadwick in 1932, by bombarding samples of boron with alpha particles from radioactive
polonium (ACSCH010).
Science as a Human Endeavour links
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Science is a global enterprise that relies on clear communication, international conventions,
peer review and reproducibility (ACSCH009)
Development of complex models and/or theories often requires a wide range of evidence
from multiple individuals and across disciplines (ACSCH010)
Radioisotopes
Radioisotopes have a wide variety of uses, including Carbon-14 for carbon dating in geology and
palaeobiology; radioactive tracers such as Iodine-131 in nuclear medicine; radioimmuno-assays for
testing constituents of blood, serum, urine, hormones and antigens; and radiotherapy that destroys
damaged cells (ACSCH011). Use of radioisotopes requires careful evaluation and monitoring because
of the potential harmful effects to humans and/or the environment if their production, use and
disposal are not managed effectively (ACSCH013). Risks include unwanted damage to cells in the
body, especially during pregnancy, and ongoing radiation produced from radioactive sources with
long half-lives.
Science as a Human Endeavour links
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Advances in science understanding in one field can influence other areas of science,
technology and engineering (ACSCH011)
The use of scientific knowledge may have beneficial and/or harmful and/or unintended
consequences (ACSCH013)
Distribution of elements in the universe
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Analysis of the distribution of elements in living things, Earth and the universe has informed a wide
range of scientific understandings, including the role of calcium exclusion from bacteria in the
evolution of shells and bones; the proliferation of carbon (rather than silicon, which has similar
properties and is more abundant in Earth’s crust) in living things; the elemental composition of
historical artefacts; and the origin of elements through nuclear fusion in stars (ACSCH011). Analysis
of element distribution is informed by data from spectral analysis and other technologies. Evidence
from these techniques enables scientists to draw conclusions about a range of phenomena, such as
the chemical changes involved in natural processes in both biological and cosmological systems, and
the geographic source of historical artefacts (ACSCH014).
Science as a Human Endeavour links
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Advances in science understanding in one field can influence other areas of science,
technology and engineering (ACSCH011)
Scientific knowledge can enable scientists to offer valid explanations and make reliable
predictions (ACSCH014)
Properties and structure of materials
Nanomaterials
Development of organic and inorganic nanomaterials is increasingly important to meet a range of
contemporary needs, including consumer products, health care, transportation, energy and
agriculture (ACSCH013). Nanomaterials have special physical and chemical properties that make
them useful for environmentally friendly products, such as more durable materials, dirt- and waterrepellent coatings designed to help reduce cleaning efforts, and insulating materials that improve
the energy efficiency of buildings (ACSCH015). Although there are many projected environmental
benefits, there are also potential risks associated with the use of nanomaterials due to the size of
the particles involved (for example, some are able to cross the human blood-brain or placental
barrier) and the unknown effects of these particles on human health and the environment
(ACSCH013).
Science as a Human Endeavour links
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•
The use of scientific knowledge may have beneficial and/or harmful and/or unintended
consequences (ACSCH013)
Scientific knowledge can be used to develop and evaluate projected economic, social and
environmental impacts and to design action for sustainability (ACSCH015)
The importance of purity
There is a large range of situations in chemistry where knowing and communicating the level of
purity of substances is extremely important. Impurities can affect the physical and chemical
properties of substances, resulting in inefficient or unwanted chemical reactions. Scientists use
methods such as mass spectrometry to identify impurities and the level of contamination
(ACSCH014). Separation methods which improve the purity of substances are used for food, fuels,
cosmetics, medical products and metals used in microelectronic devices. Scientific conventions and
international standards are used to represent the purity of materials to ensure consistent
applications of standards (ACSCH009).
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Science as a Human Endeavour links
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•
Science is a global enterprise that relies on clear communication, international conventions,
peer review and reproducibility (ACSCH009)
Scientific knowledge can enable scientists to offer valid explanations and make reliable
predictions (ACSCH014)
Carbon based life and astrobiology
Carbon is far more prevalent in living organisms than silicon, even though silicon is more abundant
than carbon in Earth’s crust. This has caused some scientists to question why life on Earth has
evolved to be carbon-based. Although carbon and silicon are found in the same group of the periodic
table and share similar characteristics, carbon has a range of properties that mean there is more
variety in its interactions and the molecules it can form, which is pivotal to biochemical molecules
such as carbohydrates, proteins and DNA. These properties of carbon, in addition to analysis of
elements found in meteorites, comets and interstellar clouds, cause many astrobiologists to theorise
that if life exists elsewhere in the universe, it will be carbon-based as it is on Earth (ACSCH010).
Astrobiology, which is concerned with the distribution of life in our own and other solar systems, is a
highly interdisciplinary field that draws on the findings of a range of scientists from areas such as
geology, molecular biology, astronomy and chemistry (ACSCH011).
Science as a Human Endeavour links
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•
Development of complex models and/or theories often requires a wide range of evidence
from multiple individuals and across disciplines (ACSCH010)
Advances in science understanding in one field can influence other areas of science,
technology and engineering (ACSCH011)
Chemical reactions: reactants, products and energy change
Minimising use of energy in industry
Industries are encouraged to reduce their energy requirements in order to save money and reduce
greenhouse gas emissions. One of the roles of chemical engineers is to consider the environmental,
safety and economic aspects of energy use in the production of chemicals and to design and monitor
chemical processes (ACSCH015). Green chemistry principles can be applied to industrial processes to
reduce energy requirements; examples of these include recycling heat energy in chemical processes
to improve efficiency and reduce cost and environmental impact, and redesigning chemical
manufacturing processes to use less energy (ACSCH013).
Science as a Human Endeavour links
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•
The use of scientific knowledge may have beneficial and/or harmful and/or unintended
consequences (ACSCH013)
Scientific knowledge can be used to develop and evaluate projected economic, social and
environmental impacts and to design action for sustainability (ACSCH015)
Energy in the body
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Our bodies rely on the exothermic reaction of respiration to provide us with sufficient energy.
Metabolism involves using the energy provided by carbohydrates, proteins and fats in our diet.
Typically, food energy is determined based on heats of combustion in a bomb calorimeter, enabling
foods to be compared based on the amount of energy they contain (ACSCH011). This information is
provided as part of the requirements for processed food labelling in many countries to help
consumers control their energy intake. In some instances this information is expressed as a
proportion of daily average energy requirements, typically using a value ranging from 7500 to 8700
kJ (ACSCH012). However each individual’s body energy requirements varies depending on their
gender, age, mode of activity and the environmental conditions they live in, so an average value may
provide limited guidance.
Science as a Human Endeavour links
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Advances in science understanding in one field can influence other areas of science,
technology and engineering (ACSCH011)
The use of scientific knowledge is influenced by social, economic, cultural and ethical
considerations (ACSCH012)
Use of fuels in society
A significant majority of the energy used for production of electricity, transport and household
heating is sourced through the combustion of fuels. Fuels, including fossil fuels and biofuels, can be
compared in terms of efficiency and environmental impact, for example by calculating the amount
of carbon emissions produced per tonne of fuel used (ACSCH015). Decisions about which fuels to
use can reflect social, economic, cultural and political values associated with the source of the fuel.
For example, cultural values might inform the use of wood for heating houses; economic and social
values might inform the use of crops for biofuel production instead of food production; and
economic, social and political values might inform the use of brown coal rather than black coal,
despite its being considered a low grade fuel (ACSCH012).
Science as a Human Endeavour links
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The use of scientific knowledge is influenced by social, economic, cultural and ethical
considerations (ACSCH012)
Scientific knowledge can be used to develop and evaluate projected economic, social and
environmental impacts and to design action for sustainability (ACSCH015)
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Unit 2
Intermolecular forces and gases
Analysing the structure of materials – forensic chemistry
Forensic science often relies on chemical processes to analyse materials in order to determine the
identity, nature or source of the material (ACSCH052). This requires detailed knowledge of both
chemical and physical properties of a range of substances as well as the structure of the materials.
Analysis techniques include different forms of chromatography to determine the components of a
mixture, for example analysis of urine samples to identify drugs or drug byproducts, identification of
traces of explosives, or the presence of an unusual substance at a crime scene. Evidence from
forensic analysis can be used to explain the nature and source of samples and predict events based
on the combination of evidence from a range of sources (ACSCH053). Calculations of quantities,
including the concentrations of solutions, are an essential part of forensic chemistry, as is
consideration of the reliability of evidence and the accuracy of forensic tests.
Science as a Human Endeavour links
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Advances in science understanding in one field can influence other areas of science,
technology and engineering (ACSCH052)
Scientific knowledge can enable scientists to offer valid explanations and make reliable
predictions (ACSCH053)
Scuba diving and the behaviour of gases
Safe scuba diving requires knowledge of the behaviour of gases with reference to volume, pressure
and temperature. In particular, divers should understand how the volume of a gas varies with the
surrounding pressure, in order to prevent damage to their respiratory, circulatory and nervous
system. Diving equipment is designed to reduce the risk of dealing with gases at high pressure,
including both the choice of materials used and the design of systems to improve efficiency and
safety (ACSCH052). Guidelines and regulations based on understanding of gas compression and
expansion due to changes in water pressure enable divers to avoid conditions such as pulmonary
barotrauma and decompression sickness (ACSCH053).
Science as a Human Endeavour links
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The use of scientific knowledge may have beneficial and/or harmful and/or unintended
consequences (ACSCH052)
Scientific knowledge can enable scientists to offer valid explanations and make reliable
predictions (ACSCH053)
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Development of VSEPR theory
Valence Shell Electron Pair Repulsion (VSEPR) theory is based on an understanding of subatomic and
molecular structure and is an extremely powerful tool in the prediction of the shapes of molecules.
In 1940 Sidgwick and Powell proposed that the shapes of molecules are dependent on the number
of valence electrons in atoms within molecules. This idea was developed further by Australian
scientist Sydney Nyholm and Canadian Ronald Gillespie in 1957 to describe how electrostatic
repulsion between bonding and/or non-bonding pairs of electrons can be used to reliably predict the
shapes of molecules (ACSCH049). They were able to demonstrate a relationship between the
internal electronic structure of molecules, as predicted by knowledge of chemical bonding, and the
overall shape of the molecules, as revealed by methods such as and X-ray crystallography
(ACSCH048). Two- and three-dimensional graphical models have been developed and adopted by
chemists to represent and communicate the shapes of molecules (ACSCH048).
Science as a Human Endeavour links
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Science is a global enterprise that relies on clear communication, international conventions,
peer review and reproducibility (ACSCH048)
Development of complex models and/or theories often requires a wide range of evidence
from multiple individuals and across disciplines (ACSCH049)
Aqueous solutions and acidity
Acid rain
Rain water is naturally acidic as a result of carbon dioxide dissolved in water and from volcanic
emission of sulphur. However scientists have observed an ongoing increase in the acidity of rain and
the reduction of the pH of the oceans, which has been explained by an increased release of acidic
gases including carbon dioxide, nitrogen oxides and sulphur dioxide into the atmosphere
(ACSCH053). Most sulphur dioxide released to the atmosphere comes from burning coal or oil in
electric power stations. Scientists have used trends in data to predict that continued increases in
acidic emissions will have adverse effects on aquatic systems, forests, soils, buildings, cultural
objects and human health (ACSCH053). Concern over acid rain has led to the design of technical
solutions such as flue-gas desulphurisation (FGD) to remove sulphur-containing gases from coal-fired
power station stacks, and emissions controls such as exhaust gas recirculation to reduce nitrogen
oxide emissions from vehicles (ACSCH054). A number of international treaties and emissions trading
schemes also seek to lower acidic emissions.
Science as a Human Endeavour links
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Scientific knowledge can enable scientists to offer valid explanations and make reliable
predictions (ACSCH053)
Scientific knowledge can be used to develop and evaluate projected economic, social and
environmental impacts and to design action for sustainability (ACSCH054)
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Blood chemistry
Blood plasma is an aqueous solution containing a range of ionic and molecular substances.
Maintenance of normal blood solute concentrations and pH levels is vital for our health. Changes in
blood chemistry can be indicative of a range of conditions such as diabetes, which is indicated by
changed sugar levels. Pathologists compare sample blood plasma concentrations to reference ranges
that reflect the normal values found in the population and analyse variations to infer presence of
disease (ACSCH050). Knowledge of blood solute concentration is used to design intravenous fluids at
appropriate concentrations, and to design plasma expanders such as solutions of salts for treatment
of severe blood loss (ACSCH052).
Science as a Human Endeavour links
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Advances in science understanding in one field can influence other areas of science,
technology and engineering (ACSCH050)
The use of scientific knowledge may have beneficial and/or harmful and/or unintended
consequences (ACSCH052)
Water quality
The issue of security of drinking water supplies is extremely important in Australia and many parts of
the Asia region. Scientists have developed regulations for safe levels of solutes in drinking water and
chemists use a range of methods to monitor water supplies to ensure that these levels are adhered
to. Water from different sources has differing ionic concentrations, for example, bore water has a
high iron content. Knowledge of the composition of water from different sources informs decisions
about how that water is treated and used (ACSCH052). Desalination plants have been built around
Australia to meet the supply needs of drinking water. These have high energy requirements and can
have unwanted environmental impacts where the water is extracted from the oceans. Scientific
knowledge and experimental evidence informs international action aimed at addressing current and
future issues around the supply of potable water (ACSCH054).
Science as a Human Endeavour links
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The use of scientific knowledge is influenced by social, economic, cultural and ethical
considerations (ACSCH052)
Scientific knowledge can be used to develop and evaluate projected economic, social and
environmental impacts and to design action for sustainability (ACSCH054)
Rates of chemical reactions
The importance of enzymes
Enzymes are specific to particular reactions and act as important catalysts in many biological
reactions, including those involved in digestion and respiration. Evidence for the existence and
action of enzymes initially arose from Louis Pasteur’s study of fermentation of sugar to form alcohol
in the nineteenth century. Further work, involving a wide range of scientists, proposed that enzyme
action was associated with protein molecules (ACSCH049). Catalysts work in a variety of ways, and
knowledge of the structure of enzyme molecules helps scientists to explain and predict how they are
able to lower the activation energy for reactions (ACSCH053). This work often relies on evidence
from laboratory experiments as well as analytical methods used to determine the structure of
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molecules (ACSCH049). For example, Australian John Cornforth was awarded the Nobel Prize for
chemistry for his study of the molecular geometry of enzymes and how they are able to catalyse
essential biochemical reactions.
Science as a Human Endeavour links
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Development of complex models and/or theories often requires a wide range of evidence
from multiple individuals and across disciplines (ACSCH049)
Scientific knowledge can enable scientists to offer valid explanations and make reliable
predictions (ACSCH053)
Cost of corrosion
Corrosion of metals can have significant negative economic, environmental and safety
consequences. For example, corrosion of steel pipes led to the 2008 gas plant explosion on Varunus
Island, Western Australia, cutting the state’s gas supply by 30%. Many heritage structures,
particularly bridges, have significant corrosion issues that compromise user safety, such as corrosion
of main cables on suspension bridges. Addressing these issues can be complex and costly, and
decisions about maintenance or replacement often involve consideration of factors such as cost,
aesthetic or cultural value, and safety (ACSCH052). Most contemporary methods of corrosion
prevention rely on knowledge of chemical and electrochemical redox processes, including the use of
grapheme within varnish coatings of iron or steel. The extension of a metal’s useful life will achieve
cost savings and improve environmental impacts for many Australian industries, where a significant
amount of industry is located on the coast and/or relies on shipping for imports and exports
(ACSCH054).
Science as a Human Endeavour links
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The use of scientific knowledge is influenced by social, economic, cultural and ethical
considerations. (ACSCH052)
Scientific knowledge can be used to develop and evaluate projected economic, social and
environmental impacts and to design action for sustainability (ACSCH054)
Development of collision theory
Collision theory enables chemists to explain and predict the rates of a vast range of chemical
reactions in many different contexts (ACSCH053). German chemist Max Trautz published research
about aspects of collision theory, in particular the significance of activation energy, in 1916. William
Lewis, working independently in England at the same time, proposed complimentary work on
collision theory in 1918 (ACSCH048). The First World War prevented not only the two chemists
working together, but even being aware of each other’s work. Further work on collision theory
enabled a quantitative approach to be taken which allowed for the prediction and control of
chemical reaction rates; these understandings are now used by chemical engineers to design
efficient, safe and economically viable industrial processes (ACSCH052).
Science as a Human Endeavour links
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Science is a global enterprise that relies on clear communication, international conventions,
peer review and reproducibility (ACSCH048)
Advances in science understanding in one field can influence other areas of science,
technology and engineering (ACSCH052)
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Unit 3
Chemical equilibrium systems
Chemical balance in wine
The production of wine, along with that of many other food products, relies on the successful
control of a range of reversible reactions in order to maintain the required chemical balance within
the product. For wine, this balance includes the acidity, alcohol concentration, sugar levels and the
colour of the wine. Techniques such as auto titration, gas chromatography and infrared spectroscopy
are used to measure the chemical composition of wine. Data from these methods, including the
analysis of multivariate data, has enabled scientists to identify how the concentrations of the various
chemicals in the wine are related, both to each other and the observable properties of wine such as
taste and aroma (ACSCH082). Sulphur dioxide is used to maintain chemical balance in wine, as it
binds with acetaldehyde. ‘Sulphite calculators’ are available so that wine makers can predict the
amount of sulphur dioxide required. However decisions as to how the sulphur dioxide is added to
the wine, including how much to use, will depend on preferences of the winemaker, especially for
those producers who market wine as ‘organic’ or ‘preservative free’ (ACSCH084).
Science as a Human Endeavour links
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ICT and other technologies have dramatically increased the size, accuracy and geographic
and temporal scope of data sets with which scientists work (ACSCH082)
The acceptance of scientific knowledge can be influenced by the social, economic, and
cultural context in which it is considered (ACSCH084)
Carbon dioxide in the atmosphere and hydrosphere
The levels of carbon dioxide in the atmosphere have a significant influence on global systems,
including surface temperatures. The oceans contribute to the maintenance of steady concentrations
of atmospheric carbon dioxide because the gas can dissolve in seawater through a range of
reversible processes. The uptake of anthropogenic carbon dioxide by the oceans is driven by the
difference in gas pressure in the atmosphere and in the oceans, and by the air/sea transfer velocity.
Because carbon dioxide is increasing in the atmosphere, more of it moves into the ocean to balance
the oceanic and atmospheric gas pressures, causing a change in the equilibrium point. Dissolved
carbon dioxide increases ocean acidity, which is predicted to have a range of negative consequences
for ecosystems, including direct impacts on oceanic calcifying organisms such as corals, crustaceans
and molluscs because structures made of calcium carbonate are vulnerable to dissolution under at
lower pH levels (ACSCH088). The United Nations Kyoto Protocol and the establishment of the
Intergovernmental Panel on Climate Change aim to secure global commitment to a significant
reduction in greenhouse gas emissions over the next decades (ACSCH087).
Science as a Human Endeavour links
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International collaboration is often required when investing in large-scale science projects or
addressing issues for the Asia-Pacific region (ACSCH087)
Scientific knowledge can be used to develop and evaluate projected economic, social and
environmental impacts and to design action for sustainability (ACSCH088)
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Development of acid/base models
Lavoisier, often referred to as the father of modern chemistry, believed that all acids contained
oxygen. In 1810, Davy proposed that it was hydrogen, rather than oxygen, that was common to all
acids (ACSCH083). Arrhenius linked the behaviour of acids to their ability to produce hydrogen ions
in aqueous solution, however this theory only related to aqueous solutions and relied on all bases
producing hydroxide ions. In 1923 Brønsted (and at about the same time, Lowry) refined the earlier
theories by describing acids as proton donators (ACSCH083). This theory allowed for the description
of conjugate acid-bases, and for the explanation of the varying strength of acids based on the
stability of the ions produced when acids ionise to form the hydrogen ions. This concept has been
applied to contemporary research into ‘superacids’, such as carborane acids, which have been found
to be a million times stronger than sulphuric acid when the position of equilibrium in aqueous
solution is considered.
Science as a Human Endeavour links
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Models and theories are contested and refined or replaced when new evidence challenges
them, or when a new model or theory has greater explanatory power (ACSCH083)
Oxidation and reduction
Breathalysers and measurement of blood alcohol levels
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).
Science as a Human Endeavour links
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People can use scientific knowledge to inform the monitoring, assessment and evaluation of
risk (ACSCH085)
Science can be limited in its ability to provide definitive answers to public debate; there may
be insufficient reliable data available, or interpretation of the data may be open to question
(ACSCH086)
Fuel cells and their uses
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
ACARA Chemistry Examples in Context February 2013
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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).
Science as a Human Endeavour links
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International collaboration is often required when investing in large-scale science projects or
addressing issues for the Asia-Pacific region (ACSCH087)
Scientific knowledge can be used to develop and evaluate projected economic, social and
environmental impacts and to design action for sustainability (ACSCH088)
Electrochemistry for clean water
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).
Science as a Human Endeavour links
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International collaboration is often required when investing in large-scale science projects or
addressing issues for the Asia-Pacific region (ACSCH087)
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Unit 4
Properties and structure of organic materials
Functional groups and organic chemistry
Over 80 per cent of all known compounds are organic compounds. Initial work in the area of organic
chemistry was based on observational chemistry, with nineteenth century attempts to organise the
diversity of organic compounds based on grouping them according to their reactions. This theory
was primarily based on empirical observations of reactivity, and did not consider the structure of the
compounds. The theory of chemical structure was initially evident in work describing the concept of
the interatomic bond, as formulated independently and simultaneously by Kekulé and Couper in
1858 (ACSCH121). Further advances in understanding of the chemical structure of carbon-based
molecules led to a classification based on functional groups. The chemical behaviour of the molecule
can now be predicted based on known chemistry of the functional groups it contains. Developments
in computer modelling have enabled more accurate visualisation and prediction of three
dimensional organic structures, such as proteins, which is critical in drug design and biotechnology
(ASCSH120).
Science as a Human Endeavour links
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ICT and other technologies have dramatically increased the size, accuracy and geographic
and temporal scope of data sets with which scientists work (ACSCH120)
Models and theories are contested and refined or replaced when new evidence challenges
them, or when a new model or theory has greater explanatory power (ACSCH121)
Green polymer chemistry
Polymers are common in daily life due to their extraordinary range of properties, and include natural
polymeric materials such as wool, silk and natural rubber, and synthetic polymers such as synthetic
rubber, neoprene, nylon, polystyrene and polypropylene. Contemporary applications of polymers
include their use in organic light emitting diodes (OLEDs) to develop television, computer and mobile
phone screens that are lighter, more flexible and more energy efficient than previous materials.
Synthetic polymers often have large “ecological footprints” as they are synthesised from fossil fuels
and do not biodegrade. There is significant research and development directed towards sustainable
polymers, produced from renewable sources such as plants, waste products and waste gases
(ACSCH126). While there have been significant advances in this field, issues remain regarding the
economic viability of this means of production, and use of food crops for the production of polymer
materials rather than food (ACSCH122).
Science as a Human Endeavour links
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The acceptance of scientific knowledge can be influenced by the social, economic, and
cultural context in which it is considered (ACSCH122)
Scientific knowledge can be used to develop and evaluate projected economic, social and
environmental impacts and to design action for sustainability (ACSCH126)
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Use of organochlorine compounds as insecticides
Organochlorine compounds, such as DDT, chlordane and lindane, were identified as powerful
insecticides in the 1950s and their use was credited with reducing malaria and increasing agricultural
productivity. Their structure makes them chemically unreactive, so they are stable in soils and in the
fatty tissues of animals. As such, they are persistent organic pollutants (POPs), accumulating in food
chains and posing a risk of causing adverse effects to human health and the environment. The
detrimental environmental effects of DDT were first hypothesised by scientists in the 1940s; when
they were popularised through a best-selling book, Silent Spring, in 1962, public reaction was
sufficiently large to prompt a government investigation (ACSCH123). Consequently DDT was banned
by the United States in 1972, and in 1995 POPs were identified as an issue requiring global action by
the United Nations, resulting in a range of organochlorine compounds being banned for agricultural
use worldwide under the Stockholm Convention in 2001 (ACSCH125). However some
organochlorine compounds are still licensed for use under strict guidelines. For example, they are
used to control fire ants, which are a serious social, economic and environmental threat in Australia,
the Philippines, Taiwan and parts of New Zealand (ACSCH125).
Science as a Human Endeavour links
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People can use scientific knowledge to inform the monitoring, assessment and evaluation of
risk (ACSCH123)
International collaboration is often required when investing in large-scale science projects or
addressing issues for the Asia-Pacific region (ACSCH125)
Chemical synthesis and design
Green synthesis methods and atom economy
Future challenges in Australia and the Asia region in resource, environmental and economic
sustainability demand more efficient chemical processes. The concept of atom economy was
proposed by American Barry Trost in the 1990s. It is a way of describing the efficiency of a reaction,
by dividing the molecular mass of the desired product by the combined molecular masses of all
reactants. Many established large-scale industrial chemical processes in the petrochemical industry
have a low atom economy, resulting in unwanted byproducts and waste management issues. Green
chemistry aims to increase the atom economy of chemical processes by designing novel reactions
that can maximise the desired products and minimise byproducts (ACSCH126). Designing new
synthetic schemes that can simplify operations in chemical productions, and seeking greener
solvents that are inherently environmentally and ecologically benign, are also important in
developing sustainable chemical industries (ACSCH126).
Science as a Human Endeavour links
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Scientific knowledge can be used to develop and evaluate projected economic, social
and environmental impacts and to design action for sustainability (ACSCH126)
Biofuel synthesis
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Dwindling supplies of economically viable sources of fossil fuels and concerns related to carbon
emissions have prompted research into the synthesis of biofuels (ACSCH126) from plant feedstocks
such as algae, oil seeds and wood waste, or from waste materials such as food industry waste oils
(ACSCH126). In the 1990s, a number of plants producing biodiesel were established in Europe and
biodiesel is now available at many service stations across Europe. Biofuels are more complex than
petroleum-based fuels, many comprising of a range of alcohols or methyl esters. Analysis techniques
such as spectroscopy and mass spectrometry can be used to investigate the combustion processes of
these ‘oxygenated’ fuels, and predict any potential harmful emissions from their combustion
(ACSCH123). While biofuels may address issues of renewable fuel supply, there are concerns that a
focus on biomass plantations as feedstocks may result in reduced available land for food production,
and an increase in food prices and availability (ACSCH126).
Science as a Human Endeavour links
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People can use scientific knowledge to inform the monitoring, assessment and evaluation of
risk (ACSCH123)
Scientific knowledge can be used to develop and evaluate projected economic, social and
environmental impacts and to design action for sustainability (ACSCH126)
Development of molecular manufacturing processes
Molecular manufacturing (or molecular assembly) is an area of developing science that involves
building objects to atomic precision using robotic mechanisms to position and react molecules
(ACSCH120). A recent publication in the peer-reviewed international journal Science reported that
researchers had developed a new way of developing sequence-specific peptides using a rotaxane as
a ‘molecular machine’. Proponents of molecular manufacturing argue that it has the potential to
quickly develop products such as stronger materials and smaller, faster and more energy-efficient
computers. They claim it will address a range of global issues through provision of vital materials and
products at a greatly reduced cost and environmental impact. However other groups caution that
cheap, rapid manufacturing capacity could also lead to a range of social, economic and
environmental issues, and requires international regulations and policies to be in place before the
technology becomes widely available. Some scientists predict that a ‘molecular manufacturing
revolution’ will occur within the next 20 to 50 years, while others are sceptical that the methods
used will ever become economically viable (ACSCH124).
Science as a Human Endeavour links
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ICT and other technologies have dramatically increased the size, accuracy and geographic
and temporal scope of data sets with which scientists work (ACSCH120)
Science can be limited in its ability to provide definitive answers to public debate; there may
be insufficient reliable data available, or interpretation of the data may be open to question
(ACSCH124)
ACARA Chemistry Examples in Context February 2013
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