9.4 chemical monitoring and management (hsc chemistry)

9.4 Chemical Monitoring and Management

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1. Much of the work of chemists involves monitoring the reactants and products of reactions and managing reaction conditions Outline the role of a chemist employed in a named industry or enterprise, identifying the branch of

chemistry undertaken by the chemist and explaining a chemical principle that the chemist uses Forensic Chemist:

Branch of Chemistry – Analytical Chemistry (Identification and qualification of materials) Mostly employed by federal, state or local government lab They analyses and identifies the type and quantity of a substance in materials, to trace their

origins. They must ensure no contamination of samples at any one time One technique used is gas chromatography. If stationary phase in this technique is liquid, the

chemical principle used is ‘solubility’ in which different components dissolve into liquids at different rates, so they can be separated and then measured

Identify the need for collaboration between chemists as they collect and analyse data

Chemists works as part of a team as chemistry is a very broad subject and each chemist specialises in one specific part of chemistry

To ensure efficient operation of a chemical plant or laboratory, collaboration between chemists is essential

Other reasons includes: safety is maintained, equipment are functioning properly, contamination issues and waste disposal

Describe an example of a chemical reaction such as combustion, where reactants form different

products under different conditions and thus would need monitoring During combustion reactions, careful monitoring is needed as different reaction conditions can

produce different product In the engine of the car, monitoring is required to ensure enough oxygen for complete

combustion to occur

In this reaction, the product produced are abundant on the Earth’s atmosphere therefore safety is ensure

In this reaction, the product produced is water and carbon monoxide. Monoxide is a toxic gas and will caused danger to living things when inhaled

In this equation, three products are formed: Water, Carbon Monoxide and Carbon Soot. Carbon Monoxide is a toxic gas while carbon soot is a solid. The solid will block the engine and will danger both the driver and road users and is car can break down anytime.

Thus, it is important for monitoring to occur as it will ensure the safety for the environment and road users

Nowadays, due to the rapid development of technology, it is ensured that all engine will undergo complete combustion therefore no pollution results

Gather, process and present the information from secondary sources about the work of practising

scientists identifying: The variety of chemical occupations:

Environmental Chemist Waste Management Chemist Biochemist Organic Chemist Forensic Chemist


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A specific chemical occupation for a more detailed study Forensic Chemist:

Forensic Chemist uses knowledge from chemistry, biology, materials science and genetics to analyse the evidence found in crime scene and the bodies of suspects

They uses criminalistics and analytical toxicology

Criminalistics (quantitative) examines evidence using methods such as microscopy and spot testing

Analytical Toxicology (qualitative) searches for evidence in body fluids through a range instrumental techniques

The result is used in police investigation and court trials

Forensic Chemists are employed by federal, state or local police force thus they generally work in government labs

A forensic science degree at both undergraduate and postgraduate is recommended and should specialised in the field in which they are interested in

When first started, they usually earn $30, 000 pa and will increase year by year


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2. Chemical Processes in industry require monitoring and management to maximise production Identify and describe the industrial uses of ammonia

Ammonia is a chemical global used significantly in the global industries. It is a colourless, highly irritating gas with a pungent suffocating odour It is mostly used as fertilisers (directly injected into soil as a liquid, solid or in ammonium nitrate) Also used as explosives when mixed with nitric acid – to make TNT and dynamites In textile, it is used to manufacture plastic, fabrics, pesticides, dyes and other chemicals Other uses includes household and industrial cleaning agent

Identify that ammonia can be synthesised from its component gases, nitrogen and hydrogen

Industrially, ammonia can be made through the mixture of nitrogen from air (cooling then factional distillation) and hydrogen derived from methane (methane with vaporised water)

Describe that synthesis of ammonia occurs as a reversible reaction that will reach equilibrium

The synthesis of ammonia is a reversible reaction This occurs because ammonia is formed through the mixture of hydrogen and nitrogen, once

ammonia is produced, some nitrogen and hydrogen is also formed

Identify the reaction of hydrogen with nitrogen as exothermic

The formation of ammonia will release 46kj of heat for every mole of ammonia produced, thus this is an exothermic (temperature increases) reaction

Explain why the rate of reaction is increased by higher temperature

When temperature has increased, the particles will move more quickly due to increased kinetic energy

This will increase the collisions between particles thus increases the energy available for the reaction

As there is more collisions between particles, more ammonia will be produced, therefore the rate of the reaction increases

Explain why the yield of product in the Haber process is reduced at higher temperatures using Le

Chatelier’s Principle According to Le Chatelier’s Principle, any changes in the system, it will readjust itself to minimise

the change If the temperature of the reaction increases, the equilibrium will shift to the left to reduce the

heat given, thus the reverse reaction is favoured As the reverse reaction is favoured, therefore less ammonia will be produced as equilibrium is

favouring the production of nitrogen and hydrogen Explain why the Haber process is based on a delicate balancing act involving reaction energy,

reaction rate and equilibrium The yield of ammonia is favoured by low temperature, however this will decrease the rate

dramatically thus it is necessary to have a balancing, in order to maximise production The most practical situation to achieve maximum yield is:

Moderate Temperature (500C) High Pressure (35MPa) Continual removal of product and continual injection of reactants Catalyst (Magnetite)


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Explain the use of a catalyst will lower the reaction temperature required and identify the catalyst(s) used in the Haber process The use of a catalyst will lower the activation energy thus the reaction rate will increased. This

will provide alternative pathways for reactants In the Haber process, the catalyst used consists of iron crystals in a fused mixture of some oxides.

Generally, magnetite (Fe3O4), other catalysts includes aluminium and calcium oxide Analyse the impact of increased pressure on the system involved in the Haber process

High Pressure will increase the yield of ammonia, as it will favour the production on the side with the least moles

This is due to the fact that increasing pressure will cause a greater rate of collisions between molecules as it decreases the volume of the reaction vessel

Explain why monitoring of the reaction vessel used in the Haber process is crucial and discuss the

monitoring required In the Haber process, the monitoring of the reaction vessel is required and is crucial due to the

following reasons: Temperature: This is to ensure that both the reaction rate and yield are at their optimum Pressure: Ensure high temperature and the safety of equipment Reactants and Products: Ensure they are continually provided and removed Catalyst: Ensure its purity and effectiveness

Gather and process information from secondary sources to describe the conditions under which

Haber developed the industrial synthesis of ammonia and evaluate its significance at that time in world history Nitrogen was essential for the development of fertilisers and explosive. However most of the

fertilisers originated from Chile which is a long way from Germany and United Kingdom. During World War I, the supply of nitrogen to Germany was blocked, which allowed the Haber process to be discovered

Fritz Haber and Karl Bosch developed high pressure equipment and with the use of a catalyst, ammonia is produced. It was known that ammonia can be produced through the reaction between nitrogen and hydrogen, however the yield was very small and the rate was very slow. Haber and Bosch determined the condition and catalyst needed. Soon, ammonia was produced in an industrial scale

The development of the Haber process allowed Germany to produce ammonia without relying on Chile. This continued WWI as Germany has the power to withstand British army power, as Chile has cut off their supply

World population was increasing at an increasing rate thus the demand for fertilisers has loosen due to the development of the Haber process to produce ammonia for fertiliser production


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3. Manufactured products, including food, drugs and household chemicals, are analysed to determine or ensure their chemical composition Deduce the ions present in a sample from the results of tests

Precipitation reaction: reaction of two or more solutions resulting in their precipitation. Using solubility rules, we can identify the precipitate and hence deduce the ions originally present

Flame Test: Each element has their own unique spectrum, burning a sample may result in a coloured flame that helps to identify ions.

Describe the use of atomic absorption spectroscopy (AAS) in detecting concentrations of metal ions

in solutions and assess its impact on scientific understanding of the effects of trace elements The lamp is specified to the metal being tested. The metal sample will vaporise and absorbs the

light being emitted from the lamp. The atom that is not absorbed will produce a specific wavelength in the monochromators. The photomultiplier will produced a calibrated graph where the concentration of the atom can be found

Trace elements are elements that are present in living things. AAS will measure the concentration of trace elements in living things and its surrounding to ensure that it is in the safe limit

Perform first-hand investigations to carry out a range of tests, including flame tests, to identify the

following ions: Phosphate (

), Sulfate ( ), Carbonate (

), Chloride ( ), Barium ( ), Calcium ( ), Lead ( ), Copper ( ), Iron ( / )

Cation identification: Adding Chloride will produce a white precipitate (lead) Adding Sulfate will produce a white precipitate and through flame test (apple green –

Barium, brick red – calcium) Adding Hydroxide (blue – copper, green (Iron ii), brown (Iron iii)

Anion identification: Adding Fe(III) (brown – hydroxide) Adding Fe (II) will produce a green precipitate, then adding hydrogen ion (gas – carbonate, no

gas – Phosphate) Adding Barium (white – Sulfate) Adding Lead (White – chloride)

Gather, process and present information to describe and explain evidence for the need to monitor

levels of one of the above ions in substances used in society (LEAD – Pb) Ions is needed to be monitored because it is dangerous to society as it can caused health

problems Lead is produced in paints, plumbing materials, mining + metal extractions, industrial waste and

lead-acid car batteries Found in nature (soil, water, air, human and animal bodies) Need for Monitoring – Lead is a neurotoxin and can cause heavy brain damage and in other

organs such as the heart. Lead will interfere in the development of children and can cause permanent learning and behavioural difficulties. Symptoms include abdominal pain, headache and in severe cases, death.


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Identify data, plan, select equipment and perform first-hand investigations to measure the Sulfate content of lawn fertiliser and explain the chemistry involved

Analyse information to evaluate the reliability of the results of the above investigation and to

propose solutions to problems encountered in the procedure The fertiliser was dissolved in nitric acid so that all particles do dissolve and all sulfate are

released into the solution Insoluble impurities are filter off so that they do not affect the precipitate Excess barium solution is added so that all possible precipitation forms Filter paper is weighed rather than removing filtrate from paper then weigh separately, because

the precipitate is very fine, grainy powder which is very likely to get stuck in the pores of the filter paper. It is hence more accurate to weigh the precipitate with the filter paper

Filtrate is weighed several times to ensure all water actually evaporates, leaving only the precipitate. If the precipitate remains slightly damp, the mass of the precipitate will be affected by water molecules

Calculations are based on Guy Lussac’s law of equal molar ratio (1 mole of Barium Sulfate is equivalent to 1 mole of sulfate as equation is in 1:1 molar ratio)

Gather, process and present information to interpret secondary data from AAS measurements and

evaluate the effectiveness of this pollution control The study of the concentration of pollutants in our environment has been greatly enhanced and

is more accurate and reliable since the development of AAS by Alan Walsh (Australian CSIRO Scientist)

The AAS method is a quick, easy, accurate and highly sensitive means of determining the concentration of over 65 elements

AAS allows the detection of very small concentrations from samples of air, water or food The absorbance values obtained using solutions of known concentration will allow the

generation of the calibration graph This allows the reading of specific absorbance date to find the concentration of the sample Example of AAS Monitoring:

Arsenic poisoning is quite dangerous as it can cause multiple organ failures, leading even to death

Arsenic-rich ground water is a serious threat to 20 million people in Bangladesh However because it is found in small concentration, we can only monitor it effectively using

AAS

Aim: To measure the sulfate content of ammonium sulfate lawn fertiliser

Method: Weigh a small sample of fertiliser and record your mass accurately. Completely dissolve the fertiliser in

50mL of 1.0M nitric acid. Filter any impurities. Add excess barium nitrate solution until the solution forms as

much precipitate as possible. Weigh an unused filter paper then filter off the precipitate. Weigh the

precipitation several times over some hours until a consistent weight is achieved, taking into consideration the

mass of the filter paper.

Calculations: Find the mass of filtrate (mass of fertiliser-mass of filter paper). Find the moles of filtrate ( ).

Moles of SO4=Moles of filtrate. Calculate mass of SO4. Find the percentage of fertiliser (mass of SO4/mass of

fertiliser)


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4. Human activity has caused changes in the composition and the structure of the atmosphere. Chemists monitor these changes so that further damage can be limited Describe the composition and layered structure of the atmosphere

Troposphere: Closest Region to Earth’s crust Contains most of the atmosphere gas (90%) Region where weather takes place Commercial plane fly in this region Most common particles are present: N2, O2, H2O, Ar and CO2 Temperature decrease with increasing altitude

Stratosphere: Region containing ozone layer Air pressure decreases in this region due to more spacing between molecules Spy planes and jets fly in this region Most common particles present: N2, O2, O3 Temperature increases with increasing altitude (due to UV/Ozone interaction)

Ionosphere Includes the mesosphere and the thermosphere Contains free ions, atoms and electrons Pressure is even lower in this region since there is an even greater spacing between particles Temperature decreases with increasing altitude in mesosphere Temperature increases with decreasing altitude in thermosphere

Identify the main pollutants found in the lower atmosphere and their sources

The presence of pollutants is minimal and is measured in ppm (parts per million), they still pose as a significant threat to living things on Earth

The main pollutants includes: Carbon Monoxide, found in incomplete combustion in cars, fires and cigarettes, burning of

fossil fuels, bush and farm fires. Will cause direct poison Methane, found in anaerobic decomposition of organic matter, natural gas leaking. Will

cause greenhouse effect as it absorb UV light therefore produce heat. Carbon Dioxide, found in burning fossil fuels, deforestation, volcanoes, natural

decomposition of plants and animals. Will cause greenhouse effect Nitrogen Oxides, found in high temperature combustion, power stations, burning of biomass,

soil bacteria. Will cause acid rain and photochemical smog Sulfur Dioxide, found in metal smelting and extraction processes, burning fossil fuels. Will

cause smog and acid rain Ozone, found in the diffusion from the stratosphere. Will cause respiratory problems Lead, found in leaded fuels, metal extraction processes, renovation of old buildings

containing leaded paint and electrical covering. Will cause direct poison and neurotoxin Describe ozone as a molecule able to act both as an upper atmosphere UV radiation shield and a

lower atmosphere pollutant Ozone gas makes up the ozone layer in the stratosphere. It reacts with UV radiation and diffuses

its energy thus preventing there dangerous rays from reaching Earth Ozone acts as a radiation shield and is indispensable for our safety When ozone enters the troposphere, it is considered to be a pollutant. When in direct contact

with human, ozone will cause respiratory problems, headaches and eye irritation. This happens even at extremely small concentration (1.3 ppm) Ozone has a polluting effect because it is a very unstable and hence reactive molecule


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Describe the formation of coordinate covalent bond A coordinate covalent bond is one in which the shared electrons of the bond comes from only

one of the atoms i.e. one sided sharing Demonstrate the formation of coordinate covalent bonds using Lewis electron dot structure

The formation of ozone is part of a natural cycle, initiated by UV and maintained by the reactivity and stability of molecules

O2 + UV 2*O (stable oxygen molecules are split upon contact with high energy UV rays, forming oxygen radicals)

*O + O2 O3 (the very reactive oxygen radical will attach to the oxygen molecule via an unstable coordinate covalent bond)

O3 O2 + *O (the unstable ozone molecule then breaks to reform oxygen molecules and oxygen radical)

Compare the properties of the oxygen allotropes O2 and O3 and account for them on the basis of

molecular structure and bonding

Allotropes Molecular Structure Bonding

O2

It has a linear molecule shape thus it is essential for life

Prepare by electrolysis of water

It is odourless and colourless

It has a stable double bond (Covalent Molecular Bond)

It is non-polar

It is partly soluble in water

It is reactive with metal forming metal oxides

O3

It has a bent shape thus it causes respiratory problems even at extremely low concentration

Pungent odour and colourless

O2 + UV 2*O

*O + O2 O3

It has a double bond (covalent molecular bond)and a coordinate covalent bond

It is unstable and more reactive than O2

It a polar (dipole-dipole) due to the uneven distribution of electrons

Soluble in water

Compare the properties of the gaseous forms of oxygen and the oxygen free radical

Property O Radical O2 Molecule O3 Molecule

Colour Only last for a few moment

Colourless gas Condenses to pale blue liquid

Colourless gas Condenses to a distinctly blue liquid

Odour ---- Odourless Strong and distinctive odour detectable at 0.1ppm

Effect on Humans

Toxic Essential for life Although pure O2 for extended period will kill

Poisonous Detrimental even at 0.1ppm

MP and BP ---- MP: -219C

BP: -193C

MP: -188C

BP: -111C

Solubility in Water

---- Sparingly soluble - 9ppm at RTP (non-polar)

More soluble than O2 Polar due to uneven distribution of electron

Conductivity ---- Non-conductor Non-conductor

Chemical Stability

Very unstable since it has two unpaired electrons in its valence shell

Very Stable Easily decomposes to O2


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Reactivity Very reactive

Reacts with elements to form metal oxides Moderately strong oxidising ability

Much more reactive that O2

Identify the origins of chlorofluorocarbons (CFCs) and halons in the atmosphere

CFCs are found in aerosol cans, production of plastics, refrigeration, solvents, cleaning agents, air conditioners, dry cleaning and fire extinguishers

Halons are any compound containing a carbon chain surrounded by any halogen atom. Halogen atoms are those in group VII. CFC is an example of a halon

Identify and name examples of isomers (excluding geometrical and optical) of haloalkanes up to

eight carbon atoms Isomers are molecules/compounds that have the same molecular formula but different

molecular structure Isomers are name through the following steps:

Name the main carbon chain Name the halogen – Bromo, Chloro, Fluoro, Iodo- (In alphabetical order) Indicate how many in each functional group (di, tri, tetra) Indicate the position by putting numbers with commas separating each number

Discuss the problems associated with the use of CFCs and assess the effectiveness of steps taken to

alleviate these problems CFC are very inert in the troposphere, however as it diffuses in the stratosphere, it will come into

contact with UV radiation, which is powerful enough to break the CFC forming chlorine radicals The chlorine radicals will then react with ozone Noticing the problem, the Montreal Protocol (1987) was signed to limit the production of CFC

and by 1996, to phase out the production of CFC HCFC was initially developed to replace CFC, however as it still contain chlorine atoms (although

less), it will still cause damage to the ozone Eventually HFC were developed, as it does not contain any chlorine atoms, they do not destroy

the ozone, thus it is safe to use However HFC are still a problem to the environment because it is a greenhouse gas, thus it will

contribute to global warming Currently, CFC are banned from production

Analyse the information available that indicates changes in atmospheric ozone concentrations,

describe the changes observed and explain how this information was obtained Information was obtained by ground-based UV spectrometers (Ozone Monitoring Instrument-

OMI) which is used to produce high resolution graph of the concentration of ozone. It works by measuring the intensity of sunlight at two wavelengths that can be absorbed by the

ozone and two wavelengths that can’t be absorbed by ozone. The two are then compared Ozone concentrations above Antarctica are less than other places on Earth, due to polar region’s

favourable conditions for ozone-destroying reactions The ozone hole each spring is still getting bigger, however its size does fluctuate from year to

year and between spring and the rest of the year Due to long atmospheric lifetime of ozone-depleting chemicals in the upper atmosphere, ozone

level are not expected to show sign of recovery until 2030 despite the decreased use of ozone-depleting chemicals


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Present information from secondary sources to write the equations to show the reactions involving CFCs and ozone to demonstrate the removal of ozone from the atmosphere CFC molecules, when come into contact with UV radiation, will break down the CFC molecules

forming chlorine radicals, which is extremely reactive

Present information from secondary sources to identify alternative chemicals used to replace CFCs

and evaluate the effectiveness of their use as a replacement for CFCs Alternative chemicals used to replace CFC includes HCFC (hydro-chloro-fluoro-carbon) and HFC

(hydro-fluoro-carbon) HCFC was the initial replacement of CFC as it contains a hydrogen atom thus limiting the chlorine

atom in the carbon chain. However, as it also contains chlorine atoms, thus it will still cause damage to the ozone thus a

new replacement was made HFC was later developed to completely phase out the production of CFC and HCFC as it does not

contain any chlorine atoms thus it is safe to use However HFC still caused a problem to the environment as it is a greenhouse gas thus it can trap

heat and eventually worsen global warming Context Point 5 5.1

Concentrations of common ions: Ions are found in waterways due to both natural and man-made causes Common ions include sodium, chlorine, magnesium, carbonate, phosphate and sulfate Water with high concentration of ions is called ‘saline’ Changes in ion concentration affects aquatic ecosystems Highly saline water are not suitable for use in irrigation and farming

Total Dissolved Solids Total amount of solids dissolved in water includes common ions but also non-ionic

substances like large molecular substances Changes in concentration of TDS affects aquatic ecosystems Water with TDS>500ppm are not suitable for drinking

Turbidity The degree of transparency of water. It is determined by the amount of solids in the water

such as soil, algae, bacteria, clay etc. High turbidity will lead to water having less sunlight penetration, thus less photosynthesis,

less production of oxygen and ultimately less life Drinking water must have turbidity of <5NTU

Hardness Water that does not lather easily with soap High concentration of calcium and magnesium ions in the water Hard water does not have direct impact on health As hard water is difficult to lather, thus water appliances may be damage due to

calcium/magnesium precipitates Acidity

Amount of hydrogen ions in water Caused by acid rain, pollution, fertilisers and industrial waste Adverse impact on aquatic ecosystems, limits domestic and industrial usage of water


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Dissolved Oxygen and Biochemical Oxygen Demand DO = mg of oxygen dissolved per litre of water BOD = amount of oxygen needed per litre of water. High BOD means many bacteria and

microorganisms in the water DO is at least 5ppm for water to sustain life Pure water has BOD of 1ppm Low DO and High BOD means life cannot be sustained in waterways

5.2

Rain is able to dissolve sodium, chlorine, sulfate and magnesium ions as it flows to the waterways

As rain soaks underground and flow to underground aquifers, there will be increased amount of calcium, magnesium, sulfate and carbonate

Acidic rain will increase hydrogen ion concentration in waterways Land clearing will lead to rain running into water bodies much quicker. This increases turbidity

levels and facilitates the dissolution of ions Crops will lead to fertilisers flowing to water bodies, increasing ion concentration of nitrate and

phosphate Raw, treated sewages and industrial discharge will lead to increasing concentrations of metal

ions Rain will dissolves harmful rubbish dumbs and carries them to water ways

5.3

Before water reaches the consumers, it is cleaned and sanitised by these steps: Screening – a sieve like devices removes solid objects Flocculation – Aluminium sulfate is added to form a precipitate. This will absorb suspended

solids and bacteria. This will coagulate into heavier precipitate Clarification – The water is left to settle as the flocculated particles settles to the bottom of

tank Filtration – The water is then filtered through granular filters to remove any remaining

particulates Sanitisation – Chlorine is added to kill bacteria, pH and colour is checked and adjusted,

fluorine is added for dental health reasons These steps will remove over 99% of all bacteria and viruses in water. Also the water is filtered

with small pore filters which will remove almost all particulates and will not slow the speed 5.4

Microscopic membrane filters are used to avoid treating the water chemically Different sized filters are used for different purposes The membrane is made from synthetic polymers dissolved in a mixture of solvents. Water

soluble powder is also added. The mixture is spread out over a plate and left for the solvent to dry

The polymer membrane, formed containing particles of water-soluble powder is placed in water Remaining solvent and powder particles dissolved, leaving a very thin polymer sheet with

definite sized microscopic pores. Membranes used in reverse osmosis are made of cellulose acetate. Under pressure, these

polymers allow the passage of water molecules to flow, leaving behind, most ions, atoms and molecules

Membranes are made for water to flow across but not through it.


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The size of the pore determines which sized organisms are allowed to flow through the membrane

The finer the pore size the smaller the particles trapped and the more expensive the membrane 5.5

Precipitation reaction can be used to calculate the concentration of concentrations of common ions

Gravimetric analysis can be used to measure TDS Turbidity tube is used to see light penetration Water hardness can be seen by adding soap to hard water, or precipitation reaction can be used

for concentration of calcium and magnesium. Water hardness can also be measured by titration of EDTA

Acidity of water is measured by pH probe DO = titration – Winkler method, BOD is calculated by measuring the difference of DO of a water

sample over a couple of days 5.6

Heavy metal pollution Caused by unacceptable level of ions such as arsenic, copper, calcium and other metal ions Precipitation and flame test is used to identify the presence of metal ions Volumetric and gravimetric analysis and AAS is used to quantitatively measure the

concentration of metal ions Eutrophication

It is the decrease in dissolved oxygen in water, caused by the decay of plants and phosphates in the water, promoting algae growth

It is monitored by examining the levels of phosphate and nitrates in the water. The higher the ratio, the more polluted the sample and the higher the rate of eutrophication

5.7

Catchment area Warragamba Dam is Sydney’s main water storage dam, accounting for over 80% of Sydney’s

water uses Possible source of contamination of this catchment

Contamination includes: fertilisers and chemicals (leaching from soil to the river), wildlife promoting harmful bacteria growth in the river

The largest contamination is residential wastage which may leached into the river through soil, or dissolved ions

Chemical tests available to determine levels and type of contamination Tests includes: precipitation reaction, AAS/gravimetric analysis, turbidity tube

Physical and chemical process used to purify water The process is: Screening, Flocculation, Clarification, Filtration and Sanitisation Dot point 5.3

Chemical additives in the water and the reasons for the presence of these additives Chlorine for the killing of bacteria Fluorine for dental health reasons HCl and NaOH are added to regulate the pH to a certain level (pH of 7). Generally Sodium

Carbonate is added due to its amphoteric nature

9.4 chemical monitoring and management (hsc chemistry)

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