lingkungan air-1.pptx

7/30/2019 lingkungan air-1.pptx

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Dr.Atikah,MSi,Apt

Jurusan Kimia FMIPA

Universitas Brawijaya (UB)

2012

04/12/2012 Kimia Lingkungan Air-1 1


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Referensi From Green Chemistry and the Ten

Commandments of Sustainability, Stanley E.Manahan, ChemChar Research, Inc., 2006

[email protected]

Manahan, Stanley E. "ENVIRONMENTAL SCIENCE,TECHNOLOGY, AND CHEMISTRY"Environmental

Chemistry, Boca Raton: CRC Press LLC, 2000

mailto:[email protected]:[email protected]


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Air, dengan rumus kimia tampak sederhana H2O,merupakan substansi sangat penting dalam semua

bagian dari lingkungan.

Air mencakup sekitar 70% keberadaanya di semua

bidang lingkungan dari permukaan bumi, dengan lautansebagai reservoir terbesar

Keberadaan air mulai dari :

air asin, air atas tanah sebagai air permukaan di danau dan

sungai,

air bawah tanah sebagai air tanah,

di atmosfer sebagai uap air,

dalam ice caps kutub seperti es padat, dan

.



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Keberadaan air juga terdapat dalam banyak

segmen anthrosphere seperti dalam boiler atau

sistem distribusi air kota

Air merupakan bagian penting dari semua sistem

kehidupan dan

Merupakan media dari mana kehidupanberevolusi dan di mana ada kehidupan



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Air yang digunakan manusia harus cukupkeberadaannya dan bersih

Oleh karena itu kita perlu mengukur kuantitas dankualitas air dalam rangka untuk memahami di manamasalah air terjadi

Air dapat menjadi "terbarukan" jika penggunaan air


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H2O: RUMUS MOLEKUL

SEDERHANA, MOLEKUL KOMPLEKSSiku struktur molekul air (lihat slide berikutnya)

Molekul air

polar Muatan Positif berakhir pada anionMuatan Negatif berakhir pada kation

Molekul air membentuk ikatan hidrogen



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Water Molecule

Waters properties can best be understood by considering thestructure and bonding of the water molecule:

The water molecule is made up of two hydrogen atoms bonded toan oxygen atom.

The three atoms are not in a straight line; instead, as shown above,they form an angle of 105.

Because of waters bent structure and the fact that the oxygen atomattracts the negative electrons more strongly than do the hydrogenatoms, the water molecule behaves like a dipole having oppositeelectrical charges at either end.


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The properties of water are due to the polar nature of the water

molecule and its ability to form hydrogen bonds.

The Water Molecule



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SIFAT PENTING AIRAir memiliki sifat yang sangat penting karena

perannya sebagai:

Pelarut,

media kehidupan, perilaku lingkungan, dan

penggunaan di industri,mengikuti dasar karakteristik molekul air:



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THE PROPERTIES OF WATER, A

UNIQUE SUBSTANCEWater has a number of unique properties that are

essential to life.

Some of the special characteristics of water include itspolar character, tendency to form hydrogen bonds, andability to hydrate metal ions.

These properties are listed in Table 3.1.


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when NaCl dissolves in water as positive Na+ ions andnegative Cl- ions,

the positive sodium ions are surrounded by watermolecules with their negative ends pointed at the ions,and the chloride ions are surrounded by water moleculeswith their positive ends pointing at the negative ions, asshown in Figure 3.4.

This kind of attraction for ions is the reason why waterdissolves many ionic compounds and salts that do notdissolve in other liquids.

Water Molecule


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Polar water molecules


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hydrogen bondsA second important characteristic of the water

molecule is its ability to form hydrogen bonds.


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hydrogen bonds Hydrogen bonds also help to hold some solute

molecules or ions in solution.

This happens when hydrogen bonds form between thewater molecules and hydrogen, nitrogen, or oxygenatoms on the solute molecule (see Figure 3.5).

Hydrogen bonding also aids in retaining extremely

small particles called colloidal particles in suspensionin water.


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Water is an excellent solvent for

many materials thus it is the basic transport medium for nutrients and waste

products in life processes. The extremely high dielectric constant of water relative to other

liquids has a profound effect upon its solvent properties in that

most ionic materials are dissociated in water. water has the highest heat capacity of any liquid or solid, l cal x

g-1 x deg-1. Because of this high heat capacity, a relatively large amount of

heat is required to change appreciably the temperature of a mass

of water; hence, a body of water can have a stabilizing effectupon the temperature of nearby geographic regions. In addition, this property prevents sudden large changes of

temperature in large bodies of water and thereby protectsaquatic organisms from the shock of abrupt temperature

variations.


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Water is an excellent solvent for

many materials The fortunate consequence of this fact is that ice

floats, so that few large bodies of water ever freezesolid.

Furthermore, the pattern of vertical circulation ofwater in lakes, a determining factor in their chemistryand biology, is governed largely by the uniquetemperature-density relationship of water.


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SIFAT PENTING AIR Sebagai pelarut yang baik untuk garam, asam, basa, dan Dengan zat yang memiliki atom H, O, dan N mampu

membentuk ikatan hidrogen Sebagai pelarut dalam cairan biologis, seperti darah atau

urin Sebagai media mineral dan transportasi mineral terlarut

dalam geosfer yang mengangkut nutrisi ke akar tanamandalam tanah

Banyak digunakan dalam industri

Air memiliki tegangan permukaan sangat tinggi Cairan air seperti tetes hujan menunjukkan sifat fisk

seperti penutup lapisan tipis membran bebek mengapresiasi sifat air karena memungkinkan

mereka mengambang diatas permukaan air



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SIFAT PENTING AIR

Seekor bebek akan tenggelam dalam air yang ditambahkandeterjen telah untuk menurunkan tegangan permukaan,menyebabkan burung bernasib sangat menyedihkan

Air bersifat transparan terhadap cahaya sinar tampak dan

UV yang memungkinkan terjadinya fotosintesis padaganggang di bawah permukaan air

Air membeku pada 0oC dan memiliki kerapatanmaksimum pada temperatur 4oC, sehingga menyebabkan

badan air beringkat dengan bagian lebih dingin, lapisanpadat berada di bagian lebih bawah air



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Important Heat Characteristics of

Water High heat capacityof 4.184 joules per gram per C (J/g-

C)

Very high heat of fusion of 334 joules per gram (J/g)

Very high heat of vaporization of water is 2,259 J/g,

water vapor carries latent heat



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Karakteristik Panas Air yang Penting

Sifat fisik yang paling penting dari air yang seringdiperdebatkan adalah perilaku dengan panas.

Air cair memiliki kapasitas panas dari 4,184 joules pergram per C (J / g C),

yang berartibahwa 4,184 joule energi panas yangdibutuhkan untuk menaikkan suhu 1 gramair cair sebesar 1 C.

Ini menunjukkan kapasitas panas yang sangat tinggiuntuk menstabilkan suhu daerah di dekat badan air.

Kapasitas panas tinggi air adalah karena adanya faktabahwa molekul air sangat terikat bersama oleh ikatanhidrogen



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Besarnya energi panas diperlukan untukmemecahkan ikatan hidrogen air sehingga molekul airdapat bergerak lebih cepat pada suhu tinggi

Air juga memiliki panas fusi sangat tinggi yakni 334joule per gram (J / g).

Ini berarti diperlukan panas yang sangat tinggi untukmemecahkan bagian molekul air yang terikat secaraikatan hidrogen dalam molekul es dalam rangkamengubah es menjadi cairan air



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Es yang meleleh, asalkan baik es padat dan air cairberada bersama-sama, maka suhu tetap pada suhuleleh, yaitu suhu konstan pada 0 C.

Panas ditambahkan ke sistem digunakan untukmemecah molekul terpisah dalam es padat, bukanuntuk meningkatkan suhu.

Panas penguapan air adalah 2,259 J/g.

Artinya 2.259 joule energi panas yang dibutuhkanuntuk menguapkan 1 gram air cair

Panas ini merupakan suhu penguapan tertinggi bagikebanyakan cairan



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Panas penguapan ini memiliki pengaruh besar padabadan air dan pada cuaca.

Dengan menyerap panas begitu banyak, air berubahdari cair ke uap,

Air menstabilkan suhu atmosfer. Namun, panas laten yang terkandung dalam uap air

dilepaskan ketika uap mengembun, seperti apa yangterjadi saat hujan.

panas yang dilepas ini menghangatkan massa udaramenyebabkan massa udara meningkat, yangmerupakan kekuatan pendorong di belakang badaidan angin topan.



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Panas laten dalam bentuk uap air diuapkan darilautan di dekat khatulistiwa yang terbawa menjauhdari khatulistiwa dalam bentuk massa udara dan

dilepaskan ketika uap air terkondensasi membentukhujan.



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USAGE of WATER The water that humans use is primarily fresh surface water

and groundwater,

The sources of which may differ from each other

significantly. Thus, the water theoretically available for use is

approximately 4.6 x 1012 liters per day, or only 23centimeters per year.

At present,the U.S. uses 1.6 x 1012 liters per day, or 8centimeters of the average annual precipitation.

This amounts to an almost tenfold increase from a usage of1.66 x 1011 liters per day at the turn of the century.


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Trend dalam penggunaan air di U.SA

Pendorong tren dalam penggunaan air di AS,merupakan hasil dari:

upaya konservasi air, terutama di industri dan pertanian

Daur ulang air, termasuk penggunaan melalui beberapatingkatan membutuhkan kualitas air semakin rendah

Penggantian irigasi semprot dengan aplikasi langsungdari air untuk tanah termasuk irigasi

kontrol penggunaan air



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7.3. WATER DISTRIBUTION AND SUPPLY



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conserve water Since about 1980, however, water use in the U.S. has

shown an encouraging trend with total consumptiondown by about 9% during a time in which population

grew 16%, according to figures compiled by the U.S.Geological Survey.

This trend, which is illustrated in Figure 3.2,


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4.4. Water Utilization (in U.S.)



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conserve water It has been attributed to the success of efforts to conserve

water, especially in the industrial (including powergeneration) and agricultural sectors.

Conservation and recycling have accounted for much of thedecreased use in the industrial sector.

Irrigation water has been used much more efficiently byreplacing spray irrigators, which lose large quantities of

water to the action of wind and to evaporation, withirrigation systems that apply water directly to soil.

Trickle irrigation systems that apply just the amount ofwater needed directly to plant roots are especially efficient


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Distribution Problem of WaterA major problem with water supply is its nonuniform

distribution with location and time.

As shown in Figure 3.3, precipitation falls unevenly inthe continental U.S.

This causes difficulties because people in areas withlow precipitation often consume more water than

people in regions with more rainfall. Rapid population growth in the more arid

southwestern states of the U.S. during the last fourdecades has further aggravated the problem


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Distribution Problem of Water.


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THE CHARACTERISTICS OF BODIES OF WATER

The physical condition of a body of water stronglyinfluences the chemical and biological processes that occurin water.

Surface water occurs primarily in streams, lakes, and

reservoirs. Wetlands are flooded areas in which the water is shallow

enough to enable growth of bottom-rooted plants.

Estuaries are arms of the ocean into which streams f low.

The mixing of fresh and salt water gives estuaries uniquechemical and biological properties.

Estuaries are the breeding grounds of much marine life,which makes their preservation very important


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Waters unique temperature-density relationshipresults in the formation of distinct layers withinnonflowing bodies of water, as shown in Figure 3.6.

During the summer a surface layer (epilimnion) isheated by solar radiation and, because of its lowerdensity, floats upon the bottom layer, orhypolimnion.

This phenomenon is called thermal stratification.


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When an appreciable temperature difference existsbetween the two layers, they do not mix but behaveindependently and have very different chemical andbiological properties.

The epilimnion, which is exposed to light, may have a

heavy growth of algae. As a result of exposure to theatmosphere and (during daylight hours) because of thephotosynthetic activity of algae, the epilimnion containsrelatively higher levels of dissolved oxygen and generally isaerobic.

In the hypolimnion, bacterial action on biodegradableorganic material may cause the water to become anaerobic(lacking dissolved oxygen).

As a consequence, chemical species in a relatively reducedform tend to predominate in the hypolimnion.


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The shear-plane, or layer between epilimnion and hypolimnion,is called the thermocline During the autumn, when the epilimnion cools, a point is

reached at which the temperatures of the epilimnion andhypolimnion are equal.

This disappearance of thermal stratification causes the entirebody of water to behave as a hydrological unit, and the resultantmixing is known as overturn. An overturn also generally occursin the spring.

During the overturn, the chemical and physical characteristics ofthe body of water become much more uniform, and a number of

chemical, physical, and biological changes may result. Biological activity may increase from the mixing of nutrients. Changes in water composition during overturn may cause

disruption in water-treatment processes.


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BADAN AIR DAN KEHIDUPAN DI AIR

Stratifikasi thermal badan air menunjukkan sifat sebagaiberikut:

Pada lapisan bagian atas badan air (lapisan epilimnion) lebihhangat, kurang padat, kaya oksigendan lapisan lebih bawah (hypolimnion) , dingin lebih padat,dan miskin oksigen (Gambar 7.4) sangat mempengaruhikimia dan biologi air

Lapisan Epiliminion sering mendukung tinggipertumbuhan alga secara fotosintetik

Lapisan epilimnion yang kaya oksigen umumnyamengandung konsentrasi tinggi spesies kimia teroksidasi,

yang biasanya memiliki kandungan oksigen yang tinggi,misal: CO2 dan HCO3-untuk karbon, NO3 untuk nitrogen, danSO42- untuksulfur



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Lapisan hypolimnion sering kekurangan O dancenderung mengandung senyawa kimia cenderungtereduksi mengurangi isi species dengan kandunganoksigen rendah dan H tinggi, termasuk CH4, NH3

(atau NH4 +), dan H2S masing-masing untuk karbon,nitrogen, dan beleran

Di bawah kondisi reduksi lapisan hypolimnion, besidapat hadir sebagai Fe larut,

sedangkan di hypolimnion itu ada apadatan Fe(OH)3atau Fe2O3



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Sources and Uses of Water: The

Hydrologic Cycle The worlds water supply is found in the five parts of

the hydrologic cycle(Figure 3.1).

About 97% of Earths water is found in the oceans.

Another fraction is present as water vapor in theatmosphere (clouds).

Some water is contained in the solid state as ice andsnow in snowpacks, glaciers, and the polar ice caps.

Surface water is found in lakes, streams, andreservoirs.

Groundwater is located in aquifers underground.


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The Hydrologic Cycle: There is a strong connection between the hydrosphere,where water isfound, and the lithosphere, which is that part of the geosphereaccessible to water.

Human activities affect both.

For example, disturbance of land by conversion of grasslands or foreststo agricultural land or intensification of agricultural production mayreducevegetation cover, decreasing transpiration (loss of water vaporby plants) and affecting the microclimate.

The result is increased rain runoff, erosion, and accumulation of silt inbodies of water.

The nutrient cycles may be accelerated, leading to nutrient enrichmentof surface waters. This, in turn, can profoundly affect the chemical and biological

characteristics of bodies of water.


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Where Earths Water is Found

About 97% of Earths water is in oceans

Most of the remaining water is in the form of solid snow

and ice

Less than 1% of Earths water as water vapor and clouds

in the atmosphere, as surface water in lakes, streams, and

reservoirs, and as groundwater in underground aquifers

B di f W t d Lif i W t


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7.4. Bodies of Water and Life in Water

Stratification of a Body of Water Strongly Affects Chemicaland Biological Processes


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Living Organisms inWater Sebuah badan air normal akan menyediakan habitat

bagi sejumlah besar organisme mulaidari bersel tunggal ganggang sampai ikan.

Sehingga badan air dapat dianggap sebagai sebuahekosistem,biasanya didasarkan pada pasokanmakanan yang terdiri dari biomassa yang dihasilkansecara photosynthetic oleh ganggang dan tanamanyang hidup di dalamnya:


Biologically Mediated Processes in Water


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Biologically Mediated Processes in Water

Specialized bacteria in water can utilize oxidized

chemical species with high oxygen contents other than

molecular O2 for oxygen sources.

Example: Nitrate ion, NO3-, acts as an oxidizing agentin

the bacterially-mediated biodegradation of biomass:

C6H12O6 + 3NO3- + 6H+ 6CO2 + 3H2O + 3NH4+(7.4.3)

By mediating chemical reactions, such as the one above,

microorganisms, particularly bacteria, largely determine

the chemistry that occurs in water.

Dissolved oxygen in water is very important.

Biodegradable organic pollutants cause biochemical

oxygen demand, BOD.


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7.5. CHEMICAL PROCESSES IN WATERBiochemical processes including photosynthesis

2HCO3- (sunlight energy) {CH2O} + O2 + CO3

2- (7.5.1)

{CH2O} represents biomass

Acid-base reactions

CO32- + H2O HCO3

- + OH- (7.5.2)

Precipitation reactions Ca2+ + CO3

2- CaCO3(s) (7.5.3)

Oxidation-reduction reactions, usually carried out by bacteria are

generally ones in which chemical species gain or lose oxygen

Example: Oxidation of S in H2S

H2S + 2O2 SO42- + 2H+ (7.5.4)


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CHEMICAL PROCESSES IN WATER

Many chemical and biochemical reactions occur inwater in the environment.

Theseare discussed here on the basis of their chemicalclassification. Several of these were shown by example

reactions in Figure 7.41. The photosynthesis reaction, which utilizes sunlightenergy to produce biomass,



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CHEMICAL PROCESSES IN

WATER is shown here for the conversion of inorganic carbon

from dissolved HCO3- ion to organic carbon(biomass) abbreviated as {CHO}.

This reaction produces biomass that can be actedupon biochemically by other organisms to form thebasis of a number of important biochemical processesin water



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2. The carbonate ion, CO32-generated by photo-synthesis reacts with water

removing a hydrogen ion, H, from the watermolecule and producing OH- ion.

Reactions involving the exchange of H+ or thegeneration or consumption of OH- are acid-basereactions.

This reaction generates OH- ion, so it makes the

water more basic. The carbonate ion generated by photosynthesis may becomeinvolved in another kind of reaction as exemplified by itsreaction with dissolved calcium ion, Ca 2+, in water, to producesolid CaCO3



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This is a precipitation reaction. CaCO3 is limestone, and it is this kind of reaction,

beginning with the CO32- generated byphotosynthesis, that is responsible for large formations

of limestone rock throughout the world.3. Oxidation-reduction reactions (see Section 4.7),usually carried out by bacteria,

are common in natural waters. The bacterially-

mediated reaction of sulfate ion, SO42- acting as anoxidizing agent in the O2

-deficient bottom regions of abody of water to oxidize biodegradable organic matter,{CH2O}



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Reaksi :

is one in which the sulfate ion loses oxygen (is

reduced).As the H2S gas bubbles up through the water, it may

contact molecular oxygen and other kinds of bacteriathat cause it to undergo the following reaction in

which the sulfur is oxidized with the addition ofoxygenatoms to produce SO42-ion:


7 6 FIZZY WATER FROM UNDERGROUND


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7.6. FIZZY WATER FROM UNDERGROUND

Natural waters contain dissolved gases.

Dissolved oxygen required by fish

Dissolved carbon dioxide in some mineral waters

Carbon dioxide in Lake Nyos in the African country of Cameroon

which asphyxiated 1,700 people in 1986

Henrys Law for gas solubilities states that the solubility of a gas in

a liquid is proportional to the partial pressure of that gas in contact

with the liquid. Gas solubility decreases with increasingtemperature

Oxygen in Water


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Oxygen in Water

At 25 C the concentration of oxygen dissolved in water is onlyabout 8 milligrams per liter of water (mg/L)

Readily consumed by biodegradation of biomass (abbreviated

{CH2O}) by oxygen-utilizing bacteria:

{CH2O} + O2 CO2 + H2O

(7.6.1)

Only about 8 mg of {CH2O} consumes 8 mg of O2

7 7 (WEAK) ACID FROM THE SKY


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7.7. (WEAK) ACID FROM THE SKY

An acidis a substance that contains or produces H+ ion in water, whereas a base

is a substance that accepts H+ ion in water or contains or produces hydroxide

ion, OH-

Whether water is acidic or basic is expressed by pH:

pH = -log [H+] (7.7.1)

[H+] is the molar concentration of H+ in water, that is, the

number of moles of this ion per liter of water.

[H+], mol/L log[H+] pH

0.100 -1.00 1.00

1.00 10-3

-3.00 3.001.00 10-5 -5.00 5.00

1.00 10-9 -9.00 9.00

Acid in Water (Continued)


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Acid in Water (Continued)

The value of [H+] in pure water at 25 C is 1.00 10-7 mol/L and the pH is 7.00.

The concentration of dissolved carbon dioxide, [CO2(aq)], in water in

equilibrium with 370 ppm atmospheric air at 25 C is 1.21 10-5

mol/L. Makes water slightly acidic because

CO2 + H2O H+ + HCO3

- (7.7.2)

[H+] = 2.3 10-6 mol/L corresponding to a slightly acidic pH of 5.6

Such water is neutral, neither acidic nor basic. Water with a pH less than 7.00 is acidic, whereas water with a pH

greater than 7.00 is basic.

The average global concentration of CO2 gas in air in the year 2001 was about 370

parts per million by volume, and going up by about 1 ppm per year.

7 8 WHY NATURAL WATERS CONTAIN


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7.8. WHY NATURAL WATERS CONTAIN

ALKALINITY AND CALCIUM

Water alkalinity is the ability of water to react with and neutralize acid (H+).

Due to presence of bicarbonate ion, HCO3-, which can react as

follows with H+ ion:

HCO3- + H+ CO2(aq) + H2O (7.7.3)

Water hardness in the form of dissolved Ca2+ ion

Both water hardness and alkalinity are acquired when water containing dissolved

CO2 reacts with limestone, CaCO3: CO2(aq) + CaCO3(s) + H2O

Ca2+(aq) + 2HCO3- (7.7.4)

Carbon Dioxide and Carbonate Species in Water


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Atmospheric CO2 dissolved in water, and from biodegradation

HCO3- dissolved in water

Solid carbonates (CaCO3) in mineral formations in contact with water

Carbon Dioxide and Carbonate Species in Water

7 9 METALS IN WATER


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7.9. METALS IN WATERMetal ions in water are present as hydrated ions, such as Ca(H2O)6

2+.

Bound water molecules can be displaced reversibly by other species.

Such species include chelating agents, which can bond to metal

ions in 2 or more places to form a metal chelate.

One such chelating agent is the nitrilotriacetate anion used in some

cleaning formulations and capable of bonding to a metal ion on 4separate sites

Chelates tend to be particularly stable, and they are very important

in natural water systems.

Chelates are involved in life systems; for example, bloodhemoglobin is a chelate that contains Fe2+ ion bonded

simultaneously to 4 N atoms on the hemoglobin protein molecule

Humic Substances in Water


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Humic Substances in Water

Water in nature may contain naturally-occurringchelating agents called humic substances that are

complex molecules of variable composition left over

from the biodegradation of plant material.

Humic substances bind with Fe2+ ion to producegelbstoffe (German foryellow stuff) which is very

difficult to remove by water treatment processes.

Humic substances produce trihalomethanes, such aschloroform, HCCl3 during disinfection of water by

chlorine

7.10. Water Interactions With Other Phases


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Most important chemical and biochemical processes in water occur atinterfaces between water and another phase (usually solid)

7

S di t


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Sediments are variable mixtures of minerals, clay, silt, sand, andorganic matter Formed by

Erosion

Sloughing of banks into water

Washed in from watersheds

Chemical reactions, for example, as the result of photosynthesis:

Ca2+ + 2HCO3- + h{CH2O}(s) + CaCO3(s)+ O2(g)

Deposits solid CaCO3 (limestone)

Deposits biomass, {CH2O}

Sediments

Colloids in Water


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Very small particles suspended in water

Size ranging from very large molecules up to about 1m

Scatter light (Tyndall effect)

Unique characteristics

High surface/volume High interfacial energy

High surface/charge

Colloids in Water


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Behavior and stability of colloids are important inaquatic chemical phenomena

Formation of sediments Dispersion and agglomeration of bacterial cells

Dispersion and removal of pollutants

Waste treatment processes


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AQUATIC LIFE The living organisms (biota) in an aquatic ecosystem may

be classified as either autotrophic or heterotrophic.

Autotrophic organisms utilize solar or chemical energy

to fix elements from simple, nonliving inorganic materialinto complex life molecules that compose living organisms.

Algae are the most important autotrophic aquaticorganisms because they are producers that utilize solar

energy to generate biomass from CO2 and other simpleinorganic species.


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AQUATIC LIFE Heterotrophic organisms utilize the organic

substances produced by autotrophic organisms asenergy sources and as the raw materials for the

synthesis of their own biomass. Decomposers (or reducers) are a subclass of the

heterotrophic organisms and consist of chieflybacteria and fungi, which ultimately break down

material of biological origin to the simple compoundsoriginally fixed by the autotrophic organisms.


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AQUATIC LIFE The ability of a body of water to produce living

material is known as its productivity.

Productivity results from a combination of physical

and chemical factors.

High productivity requires an adequate supply ofcarbon (CO2), nitrogen (nitrate), phosphorus(orthophosphate), and trace elements such as iron

Water of low productivity generally is desirable forwater supply or for swimming.


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AQUATIC LIFE Relatively high productivity is required for the support

of fish and to serve as the basis of the food chain in anaquatic ecosystem.

Excessive productivity results in decay of the biomassproduced, consumption of dissolved oxygen, and odorproduction, a condition called eutrophication

AQUATIC LIFE


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AQUATIC LIFE Life forms higher than algae and bacteriafish, for examplecomprise a

comparatively small fraction of the biomass in most aquatic systems.

The influence of these higher life forms upon aquatic chemistry isminimal.

However, aquatic life is strongly influenced by the physical and chemicalproperties of the body of water in which it lives.

Temperature, transparency, and turbulence are the three main physicalproperties affecting aquatic life.

Very low water temperatures result in very slow biological processes,whereas very high temperatures are fatal to most organisms.

The transparency of water is particularly important in determining the

growth of algae. Turbulence is an important factor in mixing processes and transport of

nutrients and waste products in water.

Some small organisms (plankton) depend upon water currents for theirown mobility.


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Dissolved oxygen (DO Dissolved oxygen (DO) frequently is the keysubstance in determining the extent and kinds of lifein a body of water.

Oxygen deficiency is fatal to many aquatic animalssuch as fish.

The presence of oxygen can be equally fatal to manykinds of anaerobic bacteria.

Biochemical oxygen demand, BOD, discussed as awater pollutant, refers to the amount of oxygenutilized when the organic matter in a given volume ofwater is degraded biologically.


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Carbon dioxide Carbon dioxide is produced by respiratory processes in water andsediments and can also enter water from the atmosphere.

Carbon dioxide is required for the photosynthetic production ofbiomass by algae and in some cases is a limiting factor.

High levels of carbon dioxide produced by the degradation oforganic matter in water can cause excessive algal growth andproductivity.

The salinity of water also determines the kinds of life formspresent. Irrigation waters may pick up harmful levels of salt.

Marine life obviously requires or tolerates salt water, whereasmany freshwater organisms are intolerant of salt.


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