summary of chemical monitoring and management

8/16/2019 Summary of Chemical monitoring and management

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9.4 CHEMICAL MONITORING AND MANAGEMENT

1. Much of the work of chemists i!o"!es moitori# the re$ct$ts $% &ro%ucts of re$ctios $% m$$#i# re$ctio co%itios.

1.2.1 – Outline the role of a chemist employed in a named industry or enterprise,identifying the branch of chemistry undertaken by the chemist and explaining achemical principle that the chemist uses.1.2.2 – Identify the need for collaboration between chemists as they collect andanalyse data.1.3.1 – ather, process and present information from secondary sources about thework of practising scientists identifying! – the "ariety of chemical occupations, – aspeci#c occupation for a more detailed study.

Environmental chemists use special techniques to monitor pollution in air, chemical spills,surveying land and water pollution. They usually work for the Government or private companiesto ensure they comply with environmental guidelines.

Metallurgical chemists study metals, alloys and their properties. They also research in thedevelopment of new alloys and optimise their production. These chemists work for companiessuch as BH.

!norganic chemists research the synthesis of inorganic chemicals such as ammonia, acids andnitrates. "rganic chemists research the synthesis of organic chemicals such as solvents, soapsand hydrocar#ons. Both types of chemists are widely employed in the chemical industry.

Biochemists study the chemical interactions within living things. They research the effects of certain chemicals on living things to evaluate their potential to$icity. They may work for Government departments, pharmaceutical or agricultural industries.

olymer chemists investigate the properties of polymers and their development. They aim toimprove the structures and alter the properties of polymers to create new products. They canwork for industrial companies, government agencies and universities.

%n organic chemist, working in a linear low&density polyethylene '(()E* factory, for e$ample,may have to+

• use computers to predict the properties of the polymer #ased on different monomers,

temperature and catalyst.

• constantly monitor the equipment to ensure the required conditions and the purity of the

reagents are maintained. %n impurity may contaminate the catalyst, slow the reaction or stop it altogether. % change in the purity of the reagents may lower the quality of andor change the properties of the polymer.

• carry out quality control processes to ensure the product satisfies. % test of viscosity

would indicate if the polyethylene is suita#le to #e used as a thin&layer film. % test of density would indicate the level of #ranching in the molecule.

• evaluate the processes #y the research and development of the product including

pro#lems of contamination, #agging of product, the flow rate through the e$truder and theeconomy of production. This is why colla#oration of data is necessary #etween chemists,chemical engineers and technicians.

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1.2.3 – $escribe an example of a chemical reaction such as combustion, wherereactants form di%erent products under di%erent conditions and thus would needmonitoring.

The com#ustion of petrol in an internal com#ustion engine produces different products depending

on the a#undance of o$ygen. !n a plentiful supply, the octane #urns completely to produce car#ondio$ide and water+

-/H0/'l*1 23"-'g* → 04"-'g* 1 0/H-"'l*

!f the supply of o$ygen is less a#undant, the reaction undergoes incomplete com#ustion. This willproduce, depending on the o$ygen supply, car#on mono$ide and car#on 'soot*+

-/H0/'l*1 05"-'g* → 04"'g* 1 6H-"'l*

-/H0/'l*1 6"-'g* → 04's* 1 6H-"'l*

)ifferent driving conditions, such as stop&starting, idling and speeding, produce differentconditions for com#ustion. 7ince car#on dio$ide is a greenhouse gas, car#on mono$ide is a to$ic

gas and soot is a carcinogenic su#stance, and to minimise environmental pollution, chemicalengineers that work in the automotive industry have to monitor the levels of these gases.

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'. Chemic$" &rocesses i i%ustr( re)uire moitori#$% m$$#emet to m$*imise &ro%uctio.

2.2.1 – Identify and describe the industrial uses of ammonia.

%mmonia '8H9* is a very important industrial chemical. Most of the ammonia manufactured isused to make fertilisers such as ammonium nitrate and urea. %mmonia can #e o$idised toproduce nitric acid for the manufacture of e$plosives such as nitroglycerine. !t is also used in theproduction of plastics such as %8 and nylon as well as #eing used as a refrigerant gas.)omestically it is used as a cleaning agent and disinfectant.

2.2.2 – Identify that ammonia can be synthesised from its component gases, nitrogenand hydrogen.2.2.3 – $escribe that the synthesis of ammonia occurs as a re"ersible reaction that will reach e&uilibrium.2.2.' – Identify the reaction of hydrogen with nitrogen as exothermic.

%mmonia is manufactured #y the Ha#er process, where nitrogen gas and hydrogen gas are

reacted using an iron catalyst to form ammonia gas. This reaction is a reversi#le e$othermicequili#rium+

8-'g* 1 9H-'g* ω -8H9'g* :H ; sing collision theory, we can deduce that as the temperatures increase, the kinetic energy#etween the molecules of gas increases, thus creating more successful collisions. This in turnincreases the rate of reaction.

>nder (e hatelier?s rinciple, if the temperature of an equili#rium system is increased, theendothermic reaction is favoured. 7ince the production of ammonia is the e$othermic reaction,thus its yield will #e reduced.

2.2.0 – )xplain why the +aber process is based on a delicate balancing act in"ol"ingreaction energy, reaction rate and e&uilibrium.

The @#alancing act? is a #alance of temperature against reaction rate and against the yield of theproduct. % high temperature would reduce the yield #ut a low temperature would not provideenough activation energy for the reaction to occur. % moderate temperature is thus used with acatalyst so a lowered activation energy is reached. This com#ination allows a greater yield than ahigh temperature alone.

2.2. – )xplain that the use of a catalyst will lower the reaction temperature re&uired

and identify the catalysts used in the +aber process.

The reaction #etween hydrogen and nitrogen is very slow at room temperature since nitrogen isan unreactive molecule with a strong triple covalent #ond. % catalyst will lower the reactiontemperature required 'since too high a temperature is economically impractical and will reduceyield of ammonia*. The catalyst used in the Ha#er process is an iron catalyst, Ae 9", allows thereaction to run at a moderate temperature of a#out 23 < 223C.

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2.2.4 – 5nalyse the impact of increased pressure on the system in"ol"ed in the +aber process.

High pressure drives the molecules together, increasing the rates of reaction. 7ince the system isin equili#rium, with #oth reagents and products #eing gases, the (e hatelier?s rinciple predictsthat increased pressure on the system will favour the reaction with the lower num#er of moles.Thus the ammonia&forming reaction is favoured, and the yield is increased. !ncreased pressure isused in the Ha#er process, a#out 02 < -2Ma '023 < -23 atmospheres*.

2.2.16 – )xplain why monitoring of the reaction "essel used in the +aber process iscrucial and discuss the monitoring re&uired.

The continual monitoring of the reaction vessel of the Ha#er process is crucial. %utomaticmonitors measure a variety of conditions, mainly temperature and pressure of the reaction vesseland the stoichiometric ratio of the gases.

The ratio of the gases is necessary to ensure ma$imum yield from the reagents. The temperatureis recorded to maintain ma$imum efficiency of the yield and so that the heat generated #y thee$othermic reaction can #e fed #ack to maintain the temperature. ressure of the vessel ismonitored for safety reasons and to maintain a high yield. The catalyst is also monitored to

ensure that it is not poisoned #y gases such as " which are #y&products of the hydrogenproduction process.

2.3.1 – ather and process information from secondary sources to describe theconditions under which +aber de"eloped the industrial synthesis of ammonia ande"aluate its signi#cance at that time in world history.

AritD Ha#er was #orn in 0/4/ in russia, the son of a prosperous German chemical merchant. %fter his education, Ha#er left his father?s #usiness to study organic chemistry at the >niversity of =ena. %t the age of -2, Ha#er #egan teaching and researching physical chemistry and quicklygained recognition for his research into electrochemistry and thermodynamics.

)uring the first decade of the twentieth century, world&wide demand for nitrogenased fertilisers

was e$ceeding supply. The largest source for fertiliser production was the huge guano 'sea #irddroppings* deposits on the coast of hile. Many scientists desired to solve the pro#lem on thisfast disappearing supply of ammonia and nitrogenous compounds.

Ha#er invented his process for the large&scale production of ammonia from nitrogen andhydrogen gas, #oth of which are a#undant and ine$pensive. By using a moderate temperature'233C*, high pressure '93Ma*, an iron catalyst, he, together with arl Bosch, a chemicalengineer, was a#le to force the relatively unreactive gases to com#ine into ammonia. By this#reakthrough many further products, such as fertilisers and e$plosives could #e made.

)uring the out#reak of Forld Far ! in 060, Ha#er was placed in charge of a research centre for chemistry and physics, and placed his services #efore the German government. Aor the durationof the war, Ha#er, a loyalist to his country, produced many #reakthroughs that helped sustain

Germany.

The significance of the Ha#er process is enormous, #ecause gave Germany, though it waslandlocked, the essential raw materials for the production of fertilisers, for the growing of crops,and of nitric acid, the #asis of e$plosives. !n this way, Ha#er allowed Germany to #e independentof hile and other countries, and shouldered the German military machine with his achievementsfor four years. Fithout him, Germany would have never had a chance to win the war.

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+. M$uf$cture% &ro%ucts, ic"u%i# foo%, %ru#s $% househo"%chemic$"s,

$re $$"(se% to %etermie or esure their chemic$" com&ositio.

3.2.1 – $educe the ions present in a sample from the results of tests.3.3.1 – /erform #rst7hand in"estigations to carry out a range of tests, including 8ametests, to identify the following ions! – phosphate, – sulfate, – carbonate, – chloride, –barium, – calcium, – lead, – copper, – iron.

CATION PRECIPITATE TESTS FLAME TEST

Barium !on 'Ba-1*forms white ppt with "9

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"ne metal that must #e monitored carefully is lead. (ead is a to$ic, heavy metal. !t can damageall the organs of the #ody, especially the #rain, kidneys and reproductive system, #y disruptingenDyme function. (ead inhi#its the formation of haemoglo#in in #lood, causing anaemia andreducing the a#ility of #lood to carry o$ygen. !t can cause neurological damage in the #rain,especially in children.

(ead accumulates in the #ody and is difficult to e$crete, and increases in concentration in thehigher end of the food chain 'a process called #iomagnification*. !ts accumulation in air has #eencaused #y the 'now&ceased practice of* addition of lead into petrol, the mining and refining of leadand deterioration of leadased paints.

The health and environmental destruction of lead makes it very necessary and important tomonitor lead ion levels in our atmosphere, water, food and soil.

3.2.2 – $escribe the use of atomic absorption spectroscopy 559 in detectingconcentrations of metal ions in solutions and assess its impact on scienti#cunderstanding of the e%ects of trace elements.

%tomic a#sorption spectroscopy '%%7* is an important technique in measuring the concentrationsof metal ions in very minute quantities. !n atomic spectroscopy a liquid sample containing the

metal ion to #e tested is aspirated through a plastic tu#e into a flame hot enough to vaporise themolecules into atoms. % cathode lamp of the specific metal passes through the vaporised sample.

% detector measures the amount passing through the flame and gives out the a#sor#ance'amount a#sor#ed* reading.

The #asis of %%7 is the result of the electron structure of the atom. >nder quantum theory,electrons move to higher or lower energy levels #y a#sor#ing or releasing electromagneticradiation of a particular frequency. 7ince each element has a different set of electron energylevels, each has its own set of a#sorption lines. The greater the concentration of the metal ion,the more radiation is a#sor#ed and the less reaches the detector. %ccording to the Beel&(am#ert(aw, the amount of light a#sor#ed is proportional to the amount of a su#stance present. %cali#ration graph using solutions of known concentrations allows the concentration of theunknown to #e determined.

The development of the %%7 has allowed chemists to measure accurately and rapidlyconcentrations of metal ions in water systems and in animals and plants. 7uch has lead to our understanding of trace elements, those elements which are required #y living things in veryminute quantities. rior to this understanding, there were instances where animals had healthpro#lems in seemingly good pastureland due to deficiencies in co#alt and human illnesses, dueto lack of trace elements in their diet, could not #e diagnosed. 8ow, with atomic a#sorptionspectroscopy, these pro#lems are easily and effectively rectified.

3.3.3 – Identify data, plan, select e&uipment and perform a #rst7hand in"estigation tomeasure the sulfate content of lawn fertiliser and explain the chemistry in"ol"ed.3.3.' – 5nalyse information to e"aluate the reliability 1 of the results of the abo"ein"estigation and to propose solutions to problems encountered in the procedure.

% sample of fertiliser containing '8H*-7" was crushed #y a mortar and pestle and weighed to amass of 03 grams. !t was then dissolved in a #eaker of warm water. Ba'8" 9*- was added drop&#y&drop in e$cess until no more white precipitate of Ba7" will form. The precipitate was thenfiltered with e$tra&fine filter paper or a suction&filter, dried and weighed. The sulfate content wasthen calculated.

1 My tutor suggests this dot-point would be better expressed as “evaluate the validity”.

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The chemistry of this e$periment is totally valid- we attempt to precipitate the sulfate ions in thefertiliser with an e$cess of #arium ions. The solu#ility of Ba7" is very low so the remaining 7"

-<

in solution is negligi#le. 7o we assume, without loss of any significant precision, that all the 7" -<

precipitates as Ba7". >pon weighing the amount of Ba7" formed, we can calculate how much7"

-niversity of 7ydney?s High 7chool hemistry Forkshop, an %%7 machine was

demonstrated to us and used to test the concentration of Ae -1 ions in various samples of water.The results were as follows+

SOURCE OF WATER ABSORBANCE READING CONCENTRATION (PPM)Tap 3.339 3.3

reek 3.330- 3.-

% rusted rainwater tank 3.-2- .3

%s can #e seen, the a#ility of the %%7 technique to measure in parts per million 'ppm* allowschemists to measure metal ions of a very low concentration. However, the %%7 must #e dailycali#rated with the ion to #e measured for the machine to measure accurately. By monitoring theions that are known pollutants, atomic a#sorption spectroscopy is a very effective andine$pensive method to control pollution.

4. Hum$ $cti!it( h$s c$use% ch$#es ithe com&ositio $% the structure of the $tmos&here.

Chemists moitor these ch$#es so th$t further %$m$#e c$ -e"imite%.

'.2.1 – $escribe the composition and layered structure of the atmosphere.

The atmosphere has a layered structure, #ased on the temperature increasesdecreases relativeto the height. The troposphere is the layer closest to the earth, up to 02 km a#ove sea level,where the temperature decreases as the altitude increases. The troposphere is the layer with themost mass of gas '/3*, and all weather occurs in this layer. The ne$t closest layer, thestratosphere, e$tends from 02km to 23km altitude, where the temperature increases as thealtitude increases. The oDone @layer? is found in the #ottom of the stratosphere. The ne$t layer upis the mesosphere, up to 52km, where the temperatures fall with altitude increases. 8o water vapour or oDone is present in this layer. The thermosphere is the ne$t layer, e$tending to -33km,where temperature increases with altitude, until 0-33C. The e$osphere, the furthermost layer of the atmosphere verges into space and its limits are not defined.

2 Kudos to phen0l: the validity and reliability evaluation is adapted from his notes.

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'.2.2 – Identify the main pollutants found in the lower atmosphere and their sources.

Tropospheric pollutants are derived mainly from the com#ustion of fossil fuels in power stations,motor vehicles and industry and emissions from the smelting and purification of minerals. ar#onmono$ide and car#on 'in the form of soot* are formed from the incomplete com#ustion of fossilfuels and from natural sources such as #ushfires. "$ides of nitrogen are formed #y lightning,#acterial decay, emissions from com#ustion engines and coal&fired power&stations. Hydrocar#onsvapours are emitted from e$hausts gases and landfills and natural sources, such as ruminantanimals such as cows and sheep. 7ulfur dio$ide is produced naturally #y volcanoes and geysersand artificially #y coal&fired power&stations, com#ustion of fossil fuels and smelting of sulphidemetal ores.

'.2.3 – $escribe the o:one as a molecule able to act both as an upper atmosphere;< radiation shield and a lower atmosphere pollutant.

"Done serves as an important molecule in the upper atmosphere 'the stratosphere* #ecause,#eing reactive, it a#sor#s >I radiation to form diatomic o$ygen, and similarly, diatomic o$ygena#sor#s >I radiation to form oDone+

"9'g* → >I radiation → "-'g* 1 "J'g*oDone activation energy diatomic o$ygen o$ygen radical

"-'g* 1 "J'g* → >I radiation → "9'g*diatomic o$ygen o$ygen radical activation energy oDone

This a#sorption of >I radiation minimises the amount of radiation that reaches the earth. >Iradiation causes damage to the )8% of living cells 'in humans the depletion of protein&29 in the)8% strand*. The damage caused interrupts the genes controlling the lifespan of cells, and in turnproduces cancerous tumours. Therefore oDone is a molecule that acts as an >I radiation shieldin the upper atmosphere.

However, in the lower atmosphere 'the troposphere*, oDone is seen as a pollutant #ecause it is apoisonous gas. "Done causes eye irritation and in high concentrations 'K3.0-ppm*, #reathing

pro#lems in asthmatics. Aurthermore, oDone, #ecause of its high reactivity, attacks dou#le #ondsin molecules, especially polymers, causing their deterioration. "Done is also a component of photochemical smog.

'.2.' – $escribe the formation of a coordinate co"alent bond.

The coordinate covalent #ond is a #ond formed #y one atom donating the electron pair only. !tcan #e formed #y a molecule reacting with its radical 'i.e. an atom of the same element withunpaired electrons*. %n e$ample of this is the formation of oDone, where >I radiation, or someother form of activation energy, causes diatomic o$ygen to react with the o$ygen radical to formoDone+

"-'g* 1 "J'g* → >I radiation → "9'g*

diatomic o$ygen o$ygen radical activation energy oDone

The o$ygen radical #onds to a pair of electrons in one of the o$ygen atoms in diatomic o$ygenmolecule without @sharing? any of its own. This is the coordinate covalent #ond of oDone.

'.2.( – $emonstrate the formation of coordinate co"alent bonds using ewis electrondot structures.

9

3 Diagrams soured from http:!!hs.su.edu.au

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% coordinate covalent #ond forms when one atom in a species 'a molecule or ion containing non&metallic atoms* provides #oth electrons in the covalent #ond. 7ome ions, such as hydronium andammonium, contain a coordinate covalent #ond. !n the formation of the hydronium ion, one of thenononding electron pairs on the o$ygen atom is used to form a covalent #ond #etween thehydrogen ion 'H1* and the o$ygen atom.

'.2.* – -ompare the properties of the oxygen allotropes of O2 and O3 and account for them on the basis of molecular structure and bonding.

PROPERTY DIATOMIC OXYGEN OZONE7ym#ol "- "9M 'C* I the atoms produced arerepresented on the (ewis diagram #y+

These energetic o$ygen atoms have unpaired electrons called free radicals. The unpairedelectrons make the radical very reactive, more so than diatomic o$ygen and oDone.

'.2. – Identify the origins of chloro8uorocarbons -=-s and halons in theatmosphere.

hlorofluorocar#ons 'As* and halons '#romofluorocar#ons* were used as refrigerants in pre&06/3?s air conditioners and refrigerators, used as propellants in spray&cans and used in themanufacture of plastics. Fhen molecules of these compounds were used or leaked out, theyescaped into the atmosphere.

4 Diagrams soured from http:!!hs.su.edu.au

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'.2.4 – Identify and name examples of isomers excluding geometrical and optical of haloalkanes up to eight carbon atoms.'.3.2 – ather, process and present information from secondary sources includingsimulations, molecular model kits or pictorial representations to model isomers of

haloalkanes.

Haloalkanes are molecules that contain only car#on, hydrogen and at least one halogen 'GroupI!! of the eriodic Ta#le*, and single #onds. E$amples of haloalkanes include+

MODEL O MOLEC/LE NAME ORM/LA

tetrahloromethane

""l#

trihloromethane $hloroform%

"&"l'

()*-dibromoethane

"*+r*

*-hloropropane "'&,"l

()-dibromo-'-uoropentane

"&/+r*

(-hlorobutane "#&/"l

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!n the late 06/3s, the T"M7 'Total "Done Mapping 7pectrometer* a#oard the Nimbus-7 satelliterecorded significant thinning of the oDone layer over %ntarctica, evidence led to the acceptance of the theory that As and the chlorine radicals they produce led to the decline of the oDone layer.7ince then, very large decreases 'known as @holes?* have #een o#served #y T"M7.

There is an increase in oDone thinning during spring in %ntarctica after a long winter, #ecause icecrystal surfaces help generate molecular chlorine #y the reaction of Hl and l"8"-. The l-photodissociates with the e$tra >I radiation in spring to produce more chlorine free radicals thatincreases oDone depletion. By summer the l- levels have depleted and oDone concentrationsreturn to normal levels.

The information a#out oDone concentrations are collected #y T"M7 on satellites, spectrometerson scientific #alloons and groundased spectrometers.

'.3.3 – /resent information from secondary sources to identify alternati"e chemicalsused to replace -=-s and e"aluate the e%ecti"eness of their use as a replacement for -=-s.

As have #een replaced #y other compounds with significantly lower oDone depletion potential'")*. HAs 'hydrochlorofluorocar#ons* were the first A&replacement chemicals, since theyreact in the troposphere with "H free radicals however #ecause this was a slow reaction, someHAs still reached the stratosphere where they released chlorine atoms.

HAs 'hydrofluorocar#ons* are now more readily used as replacements of As in refrigerationand air conditioning units as they contain no chlorine atoms and thus have Dero ").Hydrocar#ons 'such as #utane* have replaced As as aerosol propellants.

HAs and hydrocar#ons are effective replacements of As and help restore the oDonedepletion that A use has caused. Fith them, As have #een removed from all developedcountries and the rate of oDone depletion, in this year, has levelled off for the first time.

0. Hum$ $cti!it( $"so im&$cts o w$terw$(s. Chemic$"moitori# $% m$$#emet $ssists i &ro!i%i# s$fe w$ter

for hum$ use $% to &rotect the h$-it$ts of other or#$isms.

(.2.1 – Identify that water &uality can be determined by considering! – concentrationof common ions, – total dissol"ed solids, – hardness, – turbidity, – acidity, – dissol"ed

oxygen and biochemical oxygen demand.

Fater quality can #e monitored #y considering the following+

oncentration ofommon !ons

!n testing water quality, the following cations are usuallydetermined+ 8a1, Mg-1, a-1, 1. The following anions are alsodetermined+ l


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selective electrodes* can #e used for #oth anions and cations.Gravimetric analysis can also #e used #y precipitating specificions out of solution.

Total )issolved 7olids

The measure of T)7 is done either #y evaporation of a water

sample, or conductivity 'in milli7iemens per metre* andmultiplying the conductivity #y 3.4/ 'for a result in mg(*. T)7indicates the levels of mineral salts in the water.

Hardness

Hardness is a measure of the water?s a#ility to @lather? 'to formsoap #u##les*. alcium and magnesium ions present, however,will precipitate and form insolu#le scum. Hardness can #edetermined quantitatively #y titrating water with E)T% or relatively#y seeing how many drops of soap solution needs to #e added tolather the water.

Tur#idity

Fater is descri#ed as tur#id if it contains suspended particles. !t ismeasured in mg( or 8T>. !t is measured #y pouring a sample of water down a cali#rated device called a tur#idity tu#e 'with a#lack cross on the #ottom*, and added until the cross can nolonger #e seen.

%cidity7ome living things can only survive in water with a specific pHlevel. %cidity 'or #asicity* of the water sample is usually measuredwith a pH meter or narrow range pH paper.

)issolved "$ygen ')"*

)issolved o$ygen levels indicate the water?s a#ility to support

aquatic life. "$ygen levels increase where there is increasedcontact #etween water and air 'such as tum#ling of water andwave formation*. )" can #e measured #y a thallium o$ygen&sensitive pro#e, or #y a Finkler titration.

Biochemical "$ygen)emand 'B")*

Biochemical o$ygen demand is a measure of the rate of o$ygenuse of microscopic organisms. !t is also an indirect measure of organic waste present in the water. % )" test is done a sample of water it is sealed and left in the dark for a period of '2* days andthe )" test repeated. The difference #etween )" levels is theB") level 'high B") levels indicate pollution*.

(.2.2 – Identify factors that a%ect the concentrations of a range of ions in solution innatural bodies of water such as ri"ers and oceans.

Aactors which affect the concentration of ions in natural water systems include+

• limatic factors, such as rain and floods+ these will initially dilute the concentration of ions

in the water, #ut over the longer term, will cause mineral ions to #e leeched from the soil

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and water. The type of rock over which the water moves will determine the types of ionspresent 'eg. limestone rocks produce a-1 and "9

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• % #ase is added to the water sample. !f a precipitate forms, the heavy metal present

could #e+ u1, Nn-1, Ae91, o-1, Mn-1, 8i-1, %l91

To monitor eutrophication of waterways, the concentrations of nitrogen, phosphorous and their ratio '8+* must #e considered.

To monitor nitrate+

• Ae7" was added into the sample, followed #y concentrated H -7". !f a #rown ring forms

halfway down the solution, 8"9

summary of chemical monitoring and management

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