Types of solutions

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Lec1:
Aqueous solutions and Colloids

Dr.Ihsan Khalil


& Dr. Khawla Ahmed

Aqueous solutions and Colloids


Solutions and colloids are essential to
life, the

solutions in living systems
are aqueous
solutions; that

is, they are made with water.

A solution is a homogenous mixture of two or more substances.

Types of solutions


A solution is a homogenous mixture of molecules, atoms ,

or ions of
two, or more different substances . The substances that make up a
solution are called its components .The components present in excess is
called the solvent .The other are called the solutes.

The three states of matter can combine in nine diffe
rent ways to form
solutions containing two components.


Types of solution

solvent

solute example

liquid

liquid alcoholic beverages

solid

liquid

an amalgam(Hg in Ag)

gas liquid

gas

solid


liquid

solid salt
-
water

solid solid metal alloys(brass or tin)

gas

gas air

liquid gas carbonated beverages

solid


gas hydrogen gas in palladium


metal


Solubility

There is a limit to the amount of solute that can be dissolved in a solvent
at a particular temperature. This called saturated solution. Solubility is
define
d as the amount of solute that dissolves in a given quantity of
solvent to form saturated solution.

The solubility depends on a number of factors:

Kind of solvent, kind of solute, temperature, pressure and physical state
of matter.

General


Rule


Like dissolves like"

*Polar solvent ( water ) is a good solvent for ionic compounds (NaCl).

*Gasoline (non polar compounds is a good solvents for other non polar
organic compounds (oil).

*A solution of liquid in

a liquid, there is no limit to the amount of one
substance that can dissolved in another,(Ethyl alcohol in water).Such a
pair of liquids is said to be completely miscible.

*Other liquids are only slightly soluble in each other (partially miscible).

Temper
ature

In general,solute,are more soluble in hot than in cold solvents.

Other solids increases only slightly, and some actually decrease.See table

below:
-


Compounds solubility at 20
0
C solubility at 10
0
0


( g/100ml)

(
g/100ml)

NaCl


36.2 39.1

NH
4
Br

97.1 146.0

KBr

59.4 102.0

NH
3

47.5 6.9

KNO
3

37.8 247.0

O
2

0.00434

0.0008

Li
2
CO
3

1.33 0.725

CaSO
4

0.21 0.16

Gases solubilities in water decrease with increa
sing temperature(boiling
water).

The solubility of a gas is greatly affected by the pressure of that gas
above the solution.

In general ,the solubility of any gas increases as the partial pressure of the
gas is increased.(solubility of O
2

&CO
2
in blood).

I
n contrast to gases the solubility of solids and liquids are practically
unchanged with a change of pressure.



1.


Weight/Weight% Percent by weight solute






=




































x100



2. Volume/Volume percent:

Percent by volume solute






















x100

3. Weight/Volume percent:




%W/V solute=




















x100

4. Low concentrations of solute are after expressed in
milligrams per
100ml.


m
g/100ml=

















(in blood& urea)


(mg pe
rcent)

5

.p
arts per million and part per billion (ppm &ppb) widely used to
express very low concentration of solute in a solution (pollutants in water
and air).


Ppm=





















kg=10
6
mg





=















Ppb=














6. Molar concentration (M):

Is a number of moles of solute per liter of solution

M =























7.Milliequivalents per liter (meq/L)

Eq:

equivalent is defined as 1mole of that ion divided by the absolute
value of its charge

Ex: 1mole Na+ contains one equivalent of sodium.


1mole Mg++contains t
wo equivalents of magnesium.


mEq/L=






















Electrolytes and non electrolytes

An electrolyte is a substance that, when dissolved in water,results

in a
solution that can conduct electricity.

A nonelectrolyte does not conduct electricity when dissolved in water.

Aqueous solution that conducts electricity is called an electrolytic
solution. One that does not is called a non electrolytic solution.

The
mode of electrolytic and non
-
electrolytic solutions has been used to
explain all the physical properties of solutions(osmosis and dialysis)

Osmosis and osmotic pressure:

Cells have limiting boundary membranes that are called plasma
membranes. These allow
the exchange of materials back and forth
between the interior of the cell and it's exterior surroundings. Osmosis
and dialysis are two ways that such

an exchange of materials occur.

Osmosis is the movement of water though an osmotic membrane from an
aqueou
s solution that is less concentrated to one that is more
concentrated.

Preventing osmosis from occurring Appling pressure is needed to stop
water movement from to place to another (osmotic pressure). The greater
the number of particles, whether ions or molecules, in a solution, the
greater it's osmotic pressure

Classificati
on of solutes in Aqueous solution

Strong electrolyte

weak electrolyte

nonelecrolyte


HCl

CH
3
COOH

(NH
2
)
2
CO Urea


HNO3


HF

CH
3
OH


HClO
4


HNO
2

Glucose


H
2
SO
4

NH
3

Sucrose


NaOH H
2
O

Nitrogen


Ba(OH)
2

Oxygen


NaCl Carbon dioxide


CaCl
2





Arrhenius Theory of Electrolytes


When ionic compounds are dissolved in water, the ions released
and they distribute themselves uniformly in the water.

Polar covalent bonds form ions when dissolved in water, non
electrolytes dissolve in water, neutral mol
ecules are released.

Hydration
: is a close association of water molecules with an ion and the
ion said to be hydrate.

According to Arrhenius model, the total number of ions
formed per mole
of electrolyte depends on the chemical formula of the electrolyte.
(
See

table below):
-


Number of ions formed per mole of electrolyte

Chemical formula

Ions formed in
aqueous solution

Number of ions in 1
mole off electrolyte

NaCl

Na
+
Cl
-

2*6.02*10
23

KNO
3

K
+

NO
-
3

2*6.02*10
23

CaCl
2

Ca
+

Cl
-

Cl
-

3*6.02*10
23

Na
3
PO
4

Na
+

Na
+

Na
+

PO
4
-
3

4*6.02*10
23



2
-

Hypertonic:

A 1M NaCl solution has a higher osmotic pressure than a
1M glucose solution, so it is hypertonic compared to 1M glucose
solution.

3
-

Hypotonic:

A 1M NaCl solution has a lower osmotic pressure than a
2M LiBr solution
, so it is hypotonic compared to a 2M LiBr solution.



Osmosis occurs when a red blood cell is placed in water. The
solution
inside the cell is
hypertonic

compared to pure water, so water
enters the cell. So much water enters that the cell is
ruptured
.


The
"rupture" of red blood cells in this way is called hemolysis (cells are
hemolysed).

Osmosis also occurs when a red blood cells is placed in a concentrated
saline solution. In this case the solution inside the cell is hypotonic
compared to the saline s
olution and osmosis occurs in the reverse
direction. Water leaves the cell and passes in to the solution.

This causes the red blood cell to shrived and
shrink. This process is called
"Crenation"
.

A 0.95% saline solution is isotonic compared to the solutio
n inside the
red blood cells. Consequently the
cells undergo

neither
"Crenation
" nor
"Hemlysis"
.

The solution to be given a patient intravenously must be isotonic with
blood.


Colloids and colloidal Dispersions

The
particles in

a solution are the size of atoms and molecules (0.05
-
0.25
nm).

Sometimes intermolecular attractions between molecules cause several
hundred or thousand of them to cluster together. The size of these
clusters range from 1
-
100 nm. Matter containing particle
s

of this size is
called a "Coll
oid
".

A
uniform dispers
ion

of a colloid in water is called a "Colloidal
-
dispersion". A colloidal dispersion usually appears cloudy. The colloid in
a colloidal dispersion is called the dispersed substance. The continuous
matt
er in which the colloid is dispersed is called the "dispersing
substance". The dispersed and dispersing substances can be liquids
solids, or gases. The eight types of colloidal dispersion are listed below




Examples of Colloidal dispersion

Dispersed subs
tance

Dispersing substance

example

Liquid

Gas

Fog, clouds

Solid

Gas

Smoke

Gas

Liquid

Foams

Liquid

Liquid

Milk, butter

Solid

Solid

Paints, glue

Gas

Solid

Foam, rubber

Liquid

Solid

Jellies, cheese

Solid

Solid

Colored glass, gems


Starch and proteins form colloidal dispersions in water. The particles in
stable colloidal dispersions have the same electrical charge. So the
particles repel each other and cannot
form particles large enough to
settle out.

Other colloids are stabilized in

water by the action of a third substance
called an "emulsifying agent".

Example:

Oil and water (immiscible) if we add soap, the oil is emulsified
by the soap. Soap is emulsifying agent. The soap breaks up the oil in to
small drops. The soap
molecules form a negatively charged layer on the
surface of each oil drop. This causes the oil
drops to repel each other
.
Bile

salts are an emulsifying agent. These salts break up the fats we eat
in to small globules that can be more effectively digested.


Dialysis And Living Systems


Cell membranes that allow small molecules and ions to pass while
holding back large molecules and colloidal particles are called "Dialyzing
membranes". The selective passage of small molecules and ions in either
direction by a

dialyzing membrane is called "Dialysis". "Dialysis" differs
from "Osmosis" in that osmotic membranes allow only solvent
molecules to pass.

The main purpose of the kidney is to cleanse the blood by removing the
waste products of metabolism and control the
concentrations of
electrolytes. 180L of blood are purified daily in adult (68Kg). 1 percent is
eliminated as urine.


References

1
-

Geoge H. Schmid, the chemical basis of life, Brow & Company
Boston 1982.

2
-

Raymond Chang, chemistry, 8
th

edition, Mc graw Hill, 20
05.

















Lec 2
:

Chemical Reactions in Aqueous Solutions



Dr. Ihsan Khalil

&
Dr.Khawla Ahmed

Chemical Reactions in Aqueous Solutions


Salts & acids and bases form ions when dissolved in water. Many
of the chemical reactions that occur

in nature take place between
substances dissolved in water.

Solubilities of Salts in water

Not all salts are soluble in water, but general statements can be make
about the solubilities of salts:
-

1
-

All salts containing ions of elements of group IA (Li
+
, ……)

are
soluble in water no matter what the anion.

2
-

All salts containing ammonium ions (NH
4
+
) are soluble in water no
matter what the anion.

3
-

All salts containing nitrates ions and acetate ions are soluble in
water no matter what the cation.

4
-

All salts containin
g Cl
-


are soluble in water

except when the
cations are Pb
2+
, Ag
+
, and Hg
+
.

5
-

All salts containing sulfate ions are soluble in water except when
the cation are Ca
2+
, Ba
2+
, Fe
3+
, Ag
+
, Hg
+

and Pb
+2
.

6
-

All salts containing sulfide ions (S
-
) are insoluble in water except
when the cation are Li
+
, Na
+
, K
+

or NH
4
+
.

7
-

Salts containing other combination of ions are generally insoluble
in water.

Ionic Reaction


Is a chemical
reaction between ions or between ions and
molecules. An ionic reaction occ
urs only if the product is one or more of
the following :

1
-

A compound insoluble in water.

2
-

A gas.

3
-

A compound that is soluble in water but does not exist as ions.

LiCl +NaNO
3


LiNO
3

+ NaCl

Li
+

+ Cl
-



Li
+

+NO
3
-

+ Na
+

+ Cl
-

NaCl + AgNO
3

AgCl +NaNO
3

Na
+

+ Cl
-

+ Ag
+

+ NO
3
-

AgCl + Na
+

+ NO
3
-


The net ionic equation is:

Cl
-

+ Ag
+

AgCl


Ions in living systems


K
+

& Mg
+2

are found in cellular fluids. Sodium and calcium are
found in the intercellular fluid.

Ca
+2

ions are needed for healthy bones and teeth, blood clotting and
regulation of the heart beat.

Trace elements of
metallic cations are needed to maintain life
hemogl
obin contains iron (Fe
2+
). These ions play an important role in the
transport of O
2

and CO
2
.

Fe
2+

& Fe
3+

are part of the cytochrome system that is involved in
oxidative phosphorylation.

Cu
+2
, Zn
+2
, Co
+2
, Mn
+2

assist enzymes in their biological roles.

The metallic ions present in trace amounts in living systems usually exist
as "complex ions". A complex ion is made up of one or more metallic
cations surrounded by other ions or molecules
contain Na, O or sulfur
atoms that form bonds with the metallic cat
ion.

Complex ions are crucial to many chemical and biological processes.

Ag(NH
3
)
2
+

, Cu(CN)
4
2
-
, Cu(NH
3
)
4
+2
, Cd(CN)
4
2
-

The molecules or ions that surround the metal in a complex ion are
called "ligands". Every ligand

has at least one unshared pair of valence
electrons


O
:

& N



H H H H H

The atom in a ligand that is bound directly to the metal atom is known as
the "donor a
tom". Depending on the number of donor atoms, ligands
are classified as:

Monodentate, bidentate, or polydentate.

H
2
O, NH
3
,

H N


H H
2
N


CH
2

CH
2

N

H
2


H

Monodentate
Bidentate ligand (
Ethtlenediamine)





O
:O:

4
-


C


C


:


O



CH
2

CH
2

:


O





N CH
2

CH
2

N







2

CH
2






C C



:


O




:


O

:





EDTA (Polydentate ligand)

Sometimes the reaction of a metallic cation

and a large molecule is
poisonous to the living system (Hg
2+
, Pb
+2
). The result is that the
molecules are disrupted and are prevented from performing their
normal functions.



Chemical equilibrium


N
2

+ 3H
2


2NH
3

(200
˚
C + 30 atm)

2NH
3

3H
2

+ N
2


68% 32%


K=



















equilibrium constant

3O
2



2O
3

K=

















When K> 10
2
most of the reactants have been converted to
products. (the products are favored).



When K< 10
-
2

very small amount of product is formed. (the
reactants are favored).


The LE CHATELIER principle


If the system at equilibrium is disturbed by an externally applied
stress, the system changes in a way that this external stress is
minimized.

Hemoglobin + 4
O
2



oxyhemoglobin



Glucose

-

1
-

phosphate


Glucose


6


phosphate


K=
























= 20 (constant)




enzyme

Ionization of water

2H
2
O


H
3
O
4

+ OH
-


Ionization

[H
3
O
+
] = 1 * 10
-
7

M

[OH
-
] = 1
* 10
-
7

M

K=






















K[H
2
O]
2

= [ H
3
O
+
] [ OH
-
] = K
`

H
2
O


H
+

+ OH
-

[ H
3
O
+

] = [ H
+
]

K = K
w

= [ H
+
] [OH
-
]


= [1*10
-
7
][1*10
-
7
] = 1*10
-
14

An aqueous solution in which [H
+
] is greater than [OH
-
] is "acidic
solution". In a basic
solution [OH
-
] is greater than [H
+
].

Acids & Bases

Arrhenius defined as acid as any compound that forms a proton (H
+
) in
aqueous solution. A proton in solution is "Hydrated".

Strong Acid

Ionize completely when dissolved in water.

HCl + H
2
O


H
3
O
+

+ Cl
-


Strong acids

Weak Acids


HCl, HBr, HClO
4
, C
2
H
3
O
2
H, H
2
CO
3
,


HI, HNO
3
, H
2
SO
4


HF, HCN




Weak acids

Ionize slightly when dissolved in water

C
2
H
3
O
2
H


C
2
H
3
O
2
-

+ H
3
O
+

Bases

NaOH


Na
+

+ OH
-

Ca(OH)
2

& Mg(OH)
2

( strong bases)

Neutralization

1
-


NaOH


+

HCl




H
2
O

+


NaCl
-


neutralization reaction


Base acid water



salt solution is neither acidic nor


Basic

Na
+

+ OH
-

+ H
+

+ Cl
-




Na
+
+ Cl
-

+
H
2
O


Un
-
ionized molecule

H
+

+ OH
-



H
2
O


[
net ionic equation
]

2
-


H
2
SO
4

+ NaOH


NaHSO
4

+ H
2
O ………. Step 1


NaHSO
4

+ NaOH


Na
2
SO
4

+ H
2
O ………. Step 2

Overall reaction H
2
SO
4

+ 2NaOH


Na
2
SO
4

+ 2H
2
O


H
+

+ OH
-



H
2
O [net ionic equation]

Reactions of acids and bases with carbonic acid and it's salts

The reaction of carbonate and carbonate salts with
acids & bases

are
important for controlling both:

a
-

The

amount of CO
2
.

b
-

The acidity of blood.




Lec. 3
:

Acids and Bases

Dr. Ihsan Khalil


& Dr.Khawla Ahmed

Acids and Bases

The PH Scale


PH= log








=
-

log[H
+
]
log 10
3

= 3


[H
+
] = 1*10
-
PH



[OH
-
] = 1*10
-
POH


(1*10
-
PH
) (1*10
-
POH
) = K
w


= 1*10
-
14


PH + POH = 14

Relationship among PH, [H
+
], POH and [OH
-
]

[H
+
] M

PH

POH

[OH
-
]

1*10
0

= 1

0

14

1*10
-
14



acidic

1*10
-
1

1

13

1*10
-
13

1*10
-
2

2

12



:



1*10
-
14

14

0

1*10
0

basic


PH values of some common solution

Substance

PH

Limit juice

2.0

Stomach acid

1
-
3

Soft drinks

2
-
4

Black coffee

5

Milk

6.2
-
6.6

Urine

4.8
-
7

Urine

7
-
8.4

0.1
M (NaOH)

13


Measuring PH

a
-

PH meter.

b
-

By indicator (organic compound) Litmus paper or added directly

Red at PH < 5

Blue at PH > 8.5

Normality (N)

Acid
-
Base Titrations


Is a method of determining the amount of acid or base in a
solution.

The method is based on the chemical reaction between an acid
and a base

Normality

1 mole of HCl neutralizes 1 mole of NaOH

1 mole of H
2
SO
4

neutralizes 2 moles of NaOH

1 mole of H
2
SO
4

equivalent to 2 moles of HCl.

Gram


equivalent weight of an acid =





















Gram

equivalent weight of an base =
























The gram
-

equivalent weight of a
monoprotic

acid is the same as
its gram


molecular we
ight.



The gram


equivalent weight of a di
protic acid is half its gram
-


molecular weight.

NO. of equivalents of acid or =



























Base per mole of acid or base

1 mole of monopro
tic acid contains 1 equivalent of acid,

1 mole of a diprotic acid contains 2 equivalents of acid.



Number of equivalents in a sample=

























Normality (N)


Normality is defined as the number of
equivalents of acid or base
per liter of solution:

N =























Normality is most useful as a unit of concentration for the calculations
involved in a titration. At the equivalence point of an acid


base
titration, we know that:

NO. of equivalents of base = NO. of equivalents of acid

NO.
of equivalents of acid or base=normality of acid or base
*
volume of solution.In (L)

Normality of base + volume of base = normality of
acid * volume of acid

N
b

. V
b

= N
a

. V
a

Bronsted
Acids and

Bases




Acid any compound or ion that donates a proton.



Base any compound or ion that accepts a proton.

Hydrogen chloride HCl/ conjugate acid
-

base

pair



HCl + H
2
O



H
3
O + Cl
-



Conjugate
acid
-
base pair



Conjugate acid
-
base pair


NH
3

+ H
3
O



H
2
O + NH
4
+


Conjugate acid
-
base pair




H
2
O + H
2
O


H
3
O
+

+ OH
-


Acid1 base2 acid2

base1





HCO
3
-

+ H
3
O
+



H
2
O + H
2
CO
3

"Amphoteric behavior "


Base1 acid2 base2 acid1




HCO
3
-

+ OH
-





H
2
O + CO
3
-
2



Acid1 base2 acid2 base1


H
2
O + HCl





H
3
O
+

+ Cl
-



General rule

The stronger the acid, the weaker is its conjugate base. The weaker
an acid, the stronger is its conjugate base.


Relative strengths of some bronsted acids and their conjugate base

Acid

Base

Chemical formula

Name


Chemical formula

Name


HClO
4

Perchloric acid

ClO
4
-

Perchlorate

HBr

Hydrobromic acid

Br
-



HCl

Hydrochloric

Cl
-


H
2
SO
4

Sulphuric

HSO
4
-


HNO
3

Nitric

NO
3
-


H
3
O
+

Hydronium ion

H
2
O


HSO
4
-

Bisulphate

SO
4
-


H
3
PO
4
-

Phosphoric acid

H
2
PO
4


C
2
H
3
O
2
H

Acetic acid

C
2
H
3
O
2
-


H
2
CO
3

Carbonic acid

HCO
3
-


NH
4
+

Ammonium ion

NH
3


HCO
3
-

Bicarbonate ion

CO
3
-


H
2
O

Water

OH
-





increase acid strength

increase base strength

Ionization constants

of acids and bases

The degree of ionization of any acid is given by its
ionization
constant

(K
a
). The equilibrium constant for the ionization of an acid in water is
defined as its ionization constant.

C
2
H
3
O
2
H + H
2
O


H
3
O
+
+ C
2
H
3
O
2
-

K=














































[H
3
O
+
] = [H
+
]

K [H
2
O] = K
a

=

































"ionization constant"

H
2
CO
3

+ H
2
O


H
3
O
+

+ HCO
3
-

K
a1

=





















HCO
3
-

+ H
2
O



H
3
O
+

+ CO
3
-

K
a2

=



























Ionization Constants of acids at 25˚C

Acid

K
a

PK
a

HCl

1*10
3

3

H
2
SO
4

1*10
2

2

HSO
4
-

1.2 * 10
-
2

1.92

H
3
PO
4

7.52 *10
-
3

2.12

H
2
PO
4

6.2 * 10
-
8

7.21

HPO
4

2.2 * 10
-
13

12.6

HF

3.53 * 10
-
4

3.4

C
2
H
3
O
2
H

1.75 * 10
-
5

4.7

H
2
CO
3

4.3 * 10
-
7

6.3

HCO
3

5.61 * 10
-
11

10.3

HCN

4.93 * 10
-
10

9.31










Strong acids have large value of K
a
.



Weak acids have small value of K
a
.


PK
a

=
-

log K
a

NH
3

+ H
2
O


NH
4
+

+ OH
-

K =
[







]





















K[H
2
O] = K
b

=

















PK
b

=
-

log K
b


Ionization constants (K
b
) of some bases at 25
˚
C

Base

K
b

PK
b

PO
4
-
2

4.5 * 10
-
2

1.34

Zn(OH)
2

9.6 * 10
-
4

3.02

CO
3
-
2

1.84 * 10
-
4

3.74

Ag(OH)

1.1 * 10
-
4

3.96

NH
3

1.77 * 10
-
5

475

HCO
3
-

2.3 * 10
-
8

7.64




Weak bases have small K
b
.



Strong bases have large K
b
.

Carbonic acid is weak and unstable.

H
2
CO
3

is diprotic acid,

Carbonic acid

H
2
CO
3

+ NaOH


NaHCO
3

+ H
2
O



One way reactions

NaHCO
3

+ NaOH


Na
2
CO
3

+ H
2
O

Excess base is
neutralized in the body.




Carbonic acid is unstable in water. Much of the acid decomposes
to CO
2

and H
2
O :

H
2
CO
3



H
2
O + CO
2

in equilibrium in water.


Equilibrium lies to the right

When CO
2

is dissolved in water, a very small amount of carbonic acid is
formed.

Formulation of Carbonic acid

1
-

When CO
2

is dissolved in water.

2
-

Reaction of bicarbonate salt with a strong acid (HCl)

NaHCO
3

+ HCl


H
2
CO
3

+ NaCl


Unstable

We
can write:

NaHCO
3

+ HCl


NaCl + H
2
O + CO
2


HCO
3
-

+ H
+



H
2
CO
3

+ CO
2


net ionic equation

3
-

Reaction of a carbonate salt with a strong acid :

Na
2
CO
3

+ HCl


NaHCO
3

+ NaCl

Na
2
CO
3

+2 HCl
2NaCl + H
2
O +
CO
2


CO
3
-
+ 2H
+



H
2
CO
3



H
2
O + CO
2


Sometimes
bicarbonate salts react with acids while at other times they
react with bases:


OH
-

+ HCO
3
-



CO
3
-

+ H
2
O


H
+
+ HCO
3
-



H
2
CO
3

+CO
2


Aqueous solutions of salts

a
-

The hydrogen and hydroxide ions are not equal in the reaction of
a strong base and a weak acid.

C
2
H
3
O
2
H + NaOH



C
2
H
3
O
2
Na + H
2
O

C
2
H
3
O
2
H + OH
-



C
2
H
3
O
2

-

+ H
2
O

At equilibrium:

There are small amount of OH
-
, Na
+

and unionized acetic acid in
solution. As a result, the [OH
-
] is longer than the [H
+
] and the
solution is slightly basic.

Slightly b
asic solution can be made in two ways:

1
-

By dissolving sodium acetate in water.

2
-

By mixing equimolar amounts of sodium hydroxide NaOH and
acetic acid.

Classification of salts

1
-

Neutral salts: NaCl

HCl + NaOH


NaCl (neutral)

2
-

Basic salts:
C
2
H
3
O
2
Na

(weak acid and strong base)

3
-

Acidic salts: all acids whether strong or weak react

Buffer solutions


Buffer solution is a mixture of either a weak acis plus a salt of this
weak acid, Or a weak base plus a salt of this base.

Such mixture react with b
oth acids and bases, so small addition of either
strong acid or strong base cause little change in the PH.

A mixture of equimolar quantities of acetic acid and sodium
-
acetate
dissolved in water is a
buffer solution
.

The mixture has a large reservoir of
both weak acid molecule, and the
conjugate base of the acid.

Small amounts of a strong acid added to the buffer solution react with
the conjugate base as:

H
3
O
+
+ C
2
H
3
O
2
-



C
2
H
3
O
2
H + H
2
O {equilibrium lies to the right}



weaker acid weaker base



So, the added hydrogen ion is removed from the solution and the
PH hardly changes.



OH
-

added o the buffer solution react with molecules of acetic acid
to form acetate ion and H
2
O:

OH
-

+ C
2
H
3
O
2
H


C
2
H
3
O
2
-

+ H
2
O {equilibrium lies to the right}



So most OH
-

are removed from solution and the PH is only
changed slightly.



PH = PK
a

+ log




















{ Henderson
-
Hasselbalch eq.}

Addition of small amounts of a strong acid to an unbuffered

solution
causes drastic changes in its PH.

A buffer solution has a limited ability
to react with acids and bases without drastically changing its PH.



Acting as buffer because:

It contains both members of a conjugate acid
-
base pair. Removal
of one
of thes
e two by either chemical or physical process
destroys the buffer acition of the solution.



Continued addition of strong acids or bases to a buffer solution
eventually exhausts its ability to act as a buffer.

Buffer solution are

important in the body, because they maintain
the cid
-
base balance in the blood.

Acid
-
Base balance in Blood


Buffers are very important to chemical and biological systems. The
PH in the human body varies greatly from one fluid to another:

PH of blood = 7.4

PH gastric juice = 1.5

PH values, which are crucial for proper enzyme function and the balance
of osmotic pressure, are maintained by buffer in most cases.


H
2
PO
4
-

& HPO
4
-
2

HPO
4
-
2

+ H
3
O
+



H
2
PO
4
-

+ H
2
O

H
2
PO
4
-

+ OH
-



H
2
PO
4
+ H
2
O

Another buffer

CO
2

+ H
2
O


H
2
CO
3



HCO
3
-

+ H
+


Normally in blood there is 24 m Eq/L of HCO
3
-

to 1.2 m Eq/L of
H2CO3

PH = 7.35


7.45








When the ratio [HCO
3
-
]/[H
2
CO
3
] <



acidic condition (PH< 7.35)

This
called "
acidemia
"

The PH of the blood becomes more basic within the ration

[HCO
3
-
] / [H
2
CO
3
] > 20/1 (PH>7.45) "alkalemia"

PH > 6.8 PH > 7.8 ……. Death


acidic basic

In the
body

The body can replenish components of the buffer solution
as they are
used up or can remove from the body any excess component.

1
-

Patient with an increase in the concentration of acidic product in
the blood.

The physiological processes that causing
acidemia are called
acidosis
. The acidic product react with bicarbonate ions to
produce carbonic acid. This cause [HCO
3
-
]/[H
2
CO
3
] "to decrease"

Lmgs &

Kidneys maintain the PH by replenishing the buffer
components that are used up or removing any excess components
from the body.



Increase in H
2
CO
3

causes a corresponding increase in the amount
of CO
2
. To lose the excess of CO
2

deeper and faster breath call
ed
"
Hyperventilation"


occurs.

Kidneys can help by releasing more bicarbonate ion into the blood
and removing H
+

ion.

2
-

Patient has an illness that causes an increase in the concentration
of basic products:

The physiological processes causing alkalimia are
called alkalosis.

The basic products react with carbonic acid to form bicarbonate
ion.

The ratio [HCO
3
-
]/[H
2
CO
3
] increases



CO
2

should be conserve and use it to produce more carbonic acid.



To do this, loss of CO
2

through the lung is minimized by slow
er and
shallow breathing, called "
hypoventilation
". The kidneys can help,

by removing bicarbonate ions and hydrogen ions are added to the
blood.




































Lec. 4
: Radioactivity and Nuclear Chemistry

Dr.
Ihsan Khalil

Radioactivity and Nuclear Chemistry

Nuclear

chemistry is the study of reactions changes in atom nuclei. This
brunch of chemistry began with the discovery of natural "radioactivity"
by 'Antoine Becquerel' and grew as a result of subsequent inve
stigations
by Pierre and Marie Curie and many others.

The nuclei of unstable isotopes undergo spontaneous nuclear reactions
that cause "Particles" and "energy", called "
Nuclear radiation
",
to be
given

off. The emission of these particles and energy by isotope is called
"radioactivity". All elements having an atomic number greater than 83
(Bi) are radioactive.

Example:
-

Po


210 (
84
Po
210
)

Nuclear Stability



The stability of any nucleus is determined b
y the difference
between "Coulombic repulsion
" and the "short
-
range" attraction. If
repulsion outweighs attraction, the nucleus disintegrates, emitting
particles and/or radiation.

The principle factor that determines whether a nucleus is stable is the
n/p
ratio.

n/p
~ 1 for low atomic number

n/p > 1

for high atomic number

The following rules:

1
-

Nuclei that contain 2, 8, 20, 50, 82 or 126 protons or neutrons are
generally more stable than nuclei that do not possess these
numbers (Magic numbers).

2
-

Nucl
ei with even number of both n & p are generally more stable
than those with odd numbers of these particles.

3
-

All isotopes of the elements with atomic numbers

higher than 83
are "radioactive". All isotopes of technetium (Tc Z = 43) and
promethium (Pm, Z = 61
) are radioactive.

Types of radiation

1
-

Alpha radiation (
α

): is a stream of particles moving at about 1/10
the speed of light. Each particle is the nucleus of "helium atom".
That contain (2P and 2n) and has charge of +2. (
4
2
He). they cannot
travel very far without colliding with other particles. As a result,
these particles do little damage to "internal organs" because they
cannot penetrate the skin, but when gets inside the body by being
inhaled or
swallowed, the
α

can the damage internal organs.
212
84
Po


208
82

Pb +
4
2
α


2
-

Beta particles
0
-
1
β

:
-

is stream of electrons. The electrons are
produced within the nucleus by the transformation of a neutron
into a proton and an electron
1
0
n


1
1
P +
0
-
1
β

Example:
-

40
19

K


40
2
0
Ca +
0
-
1
β


3
-

Gamma radiation
Ȣ

:
-

is a form of energy similar to light waves, X
-
ray. This radiation has high energy and can penetrate deep within
the body and cause serious damage.

Ȣ

radiation usually occurs
along with
α

and
β

radiation.



Two less common typ
es of nuclear radiation and "
1
0
n" neutrous
and "positrons" (
0
1
β
).

Type of
radiation

Composition

Symbol

Electric charge

Approximate
penetration of skin
(cm)

Alpha

Helium
nucleus

α

4
2
He

+2

0.01

Beta

Electron

β,
0
-
1
e

-
1

1

Gamma

Energy

Ȣ

0

㄰1

Neutron

Neutron

n,
1
0
n

0

10

Positron

P
+
ositron

B
+
,
0
1
e

+1

1





Ionizing Radiation


Radiation can form ions in matter by knocking electrons off
the atoms and molecules in its path. For this reason, it is called
"
ionizing radiation
".

They are carcinogenic, damage

to the fetus and genetic damage.

Carcinogenic effect

Radiation cause cancer ( skin, bone, leukemia,…)



The effect of radiation is cumulative. High level of radiation kills
cells, so precaution must be taken when dealing with radiation.



Fetuses are sensitiv
e to radiation than adults.



Genetic risk of exposure to radiation is difficult to determine
because the genetic damage may not be seen for several
generation. Genetic damage is caused by damage to the gens in
the nuclei of cells. The damage to the structur
e of the gene may
cause death or variety of physical defects in following generation.



There is a risk of damage even at low levels of radiation, but the
risk is extremely small.

Detection ionizing radiation

1
-

Photographic method ( photographic imaging) I
-
131
.

2
-

Scintillation counter.

3
-

Geiger
-
Muller counter.

4
-

Computer imaging(Television & Computers) CAT computerized

5
-

Film badges.


Axial Tomography

Nuclear Reaction


238
92

U


234
90
Th

+
4
2

He
α



decay

16
7
N


16
8

O +
0
-
1
e
β



decay

99m
43
Tc


99
43
Tc +
Ȣ

metastable isotop

131
53
I

131
54
Xe +
0
-
1

β +
0
0
Ȣ


Half


life t
1/2

The time needed for one
-
half of the original nuclei of

an isotope to
decay to
another substances.

The importance of the t
1/2

is that it tells us how long a sample of the
isotope will exist.

234
90
Th



234
91

Pa +
0
-
1
β

t
1/2

of some Naturally occurring
Radioactive isotope

Elements

Isotope

t
1/2

Hydrogen

3
1
H

12.3 Yr

Carbon

14
6
C

5700 Yr

Potassium

40
13
K

200 million Yr

Radon

222
86
Rn

3.8 days

Radium

226
88
Ra

1600 Yr

Uranium

235
92
U

700 million Yr

Uranium

238
92
U

4.5 billion Yr

Polonium

214
84
Po

0.15 m sec.

Lead

214
82
Pb

26.8 min


Radiation dosages (units)

Curie and Becqueral

Ci

is the level of radioactivity caused by 3.7 * 10
10

radioactive
disintegrations per second. It is dependant of the size of the sample.

Picocurie (10
-
12

Ci)

Microcurie (10
-
6

Ci)

Millcurie (10
-
3
Ci)

The SI unit of radioactivity is the becqueral (Bq)

ICi = 3
.7 * 10
10
Bq

To assess biological damage caused by radiation, another units must be
used that can be compared:
Rad

Rad

Radiation absorbed dosage, is the dosage of radiation able to transfer
2.4 * 10
-
3

calories of energy to 1 kilogram of matter.

The SI unit of absorbed dose is the gray (GY). A gray is defined as 1 J of
energy absorbed per 1 Kg of tissue.

100 rad = 1 GY

The dose of 1 rad from one source is not necessarily equal to a dose of 1
rad from another.

Rem

Roentgen equivalent for man, descr
ibes the biological damage caused by
the absorption of different kinds of radiation by the body.

Rem = rad * RBE REB= relative biological effectiveness

RBE of
α

= 10

RBE of
β

= 1

1 rem = 0.01 Sv (Sievent)

The rem is a more accurate and comp
arable measure of biological
damage caused by different ionizing radiation.

LD
50

Value (lethal dose)

The dose that would be fetal for 50% of the exposed population within
30 days. Some biological effect, however, is detectable at a level as low
as 25 rem.

LD
50

value is estimated for human to be 500 rem.

LD
50

for mammals is 250


1000 rem.

LD
50

for insects
~ 50000 rem.

Some microorganisms can tolerate more.

Each person receives about
100 mrem annually from natural background
radiation.

Transmutation

Is chang
ing one element in to another, either in nature or in the
laboratory is called
transmutation
, by means of "
bombardment

reactions".

The bombardment process is often accomplished in the core of a nuclear
react
or, where an abundance of small nuclear particles
, particularly
neutrons, are available. Alternatively, extremely high velocity charges
particles (
α

and
β
) may be produced in particle accelerators, as a
"Cyclotron". Particle accelerators are extremely large and use magnetic
and electric fields to 'push'
and ' pull' charged particles toward their
target at very high speeds.

Many isotopes that are useful in medicine are produced by particle
bombardment:
-


197
79
Au +
1
0
n


198
79
Au tracer in the liver


98
42
Mo +
1
0
n


99m
43
Tc +
0
-
1
e for tracer

application

Medical uses of radioactive isotopes

1
-

To treat cancer

The radiation is directed at the cancer cell
from either outside or
inside the body, depending on the type of cancer.

Co


60 is used externally.

I


131 is used internally to treat thyroid
gland cancer.

2
-

As tracers to diagnose illnesses. The isotopes in the body can be
followed or traced by means of the radiation given off.

Na


24 is used to locate blockages in the circulatory system.

Radioactive isotopes used

in humans must be chosen carefu
lly:
-

a
-

The half life must be long enough to do its job yet short enough
that the isotope will disappear from the body.

b
-

No isotope that emit alpha particles are used.

Selected radioactive isotopes

Isotope

Half life

Emission

Use

Cobalt


60

5.3 Yr

β

,
Ȣ

Cancer therapy

Lodine


131

8 days

β

,
Ȣ

Treatment of thyroid
cancer and diagnosis of
thyroid mal
-
function

Lodine


123

13.3 hr

β


Treatment thyroid
cancer

Chromium 51



Determination blood
volume in body

Technetium
99m TC


99m

6hr


Allow early
detection
of the extent of bone
tumors and active sites
of rheumatoid arthritis

Technetium 99
m TC


99m

6 hr


Determine cardiac
output

Technetium
99m

6.1 hr

Β

Brain, kidney, and lung
scans


Nuclear medicine

The diagnosis of a host of biochemical
irregularities or disease of the
human body has been made routine through the use of radioactive
"
tracers"
. Tracers are small amount of radioactive substa
nces that are
used as probs to study internal organs.

Example:
-

I


127 the most abundant nonradioacti
ve isotope.


I


131 & I


125 are radioactive and behave in the same way


And are used to study thyroid.

Isotopes with short half


lives are preferred for tracer studies.

Magnetic Res
onance Imaging

Nuclei, like electrons, exist in different energy states (levels). Under the
influence of electromagnetic radiation, transitions involving absorption
of radiation can occur between the various nuclear states. Transition
occur

in the microwave region of the electromagnetic radiation under
the influence of a magnetic field.

Nuclear magnetic resonance (NMR) has become a useful tool for the
study of molecules containing hydrogen.

In 1970s and 1980s this experimented technique was
extended beyond
tiny laboratory samples of pure compounds to the most complex sample
'the human body'. The result of these experiments is termed "
Magnetic
Resonance Imaging
".

MRI, requires no use of radioisotopes and is quick, safe, and painless.

Energy
and Nuclear reactions

1
-

Fission reaction
:

the nuclear reaction that causes an atom to split
into several smaller parts is called fission reaction. This splitting
process is accompanied by the release of large amount of energy.

A nuclear power
plant uses a f
issionable material (one that is
capable of undergoing fission) such as U


125, as fuel.



U


235 is the only naturally occurring isotope that undergoes this
rea
ction.



Two other isotopes formed by nuclear bombardment, PU


239
and U


233 also undergo fiss
ion reactions.


1
0
n +
235
92
U


thermal



+
143
54
Xe +3
1
0
n


103
42
M
o

+
131
50
Sn + 2
1
0
n + energy

90
83
Sr + Energy




135
53
I +
97
53
Y + 4
1
0
n + Energy

Each neutrons released react with other nuclei this is called chain
reaction. The amount of material needed for a chain reaction to
continue is called the "
Critical Mass
".

Breeder Reactors

A
breeder reactor uses U


238 which is abundant but non fissionable, in
a series of steps the U


238 is converted to PU


239 which is fissionable
and undergoes fission chain reaction, producing energy.

Nuclear fusion

Results from combination of two small
nuclei to form a large nucleus

with

the release of large amount of energy.


2
1
H +
3
1
H


4
2
He +
1
0
n + energy

Such fusion reaction occur in two places in the world:
-

1
-

In the sun.

2
-

In the hydrogen bomb.

The high temperature needed to carry out the fusion reaction is
furnished by the explosion of an atomic bomb. The atomic bomb is set
off first and provides the uergy to trigger the hydrogen bomb.

References

1
-

Gorge H. Schmid, the chemical basis of life, litt
le Brow and
company, 1
st

edition (1982).

2
-

Robert L. caret, Katherine J.Denniston, and Joseph J. Topping,
principles and Applications of
Inorganic, Organic and biological
chemistry, W.m.c. Brown publisher, (1993).

3
-

Raymond Chang, chemistry, 8
th

edition, Mc Gr
ow


Hill company
publisher, (2005).




Lec.5
:

Pollution


Dr. Ihsan Khalil

Pollution

Pollution can be defined as undesirable change in our environment,
as a result either, direct or indirect, action of human through an
effect on type of energy, radiation level, and in chemical and physical
structure of life. Pollution may affect the way of

life activity such as
water supply, agriculture, products, food,….

Effect of pollution

The effect of pollution may conclude human being, animals and
plants, so it is important to know the sources of pollution and their
effect.

Types of pollution

1
-

Air pollu
tion:
-

mainly the products of oxidation from combustion
of fuels. And the air pollutant are CO, colloids, SO
2
, hydrocarbons,
No
2

(from Gasoline, diesel, natural gas, coal,…..)

Aerosols

Any suspension of colloidal or near colloidal particles in a gas is cal
led
"
Aerosol
". The particles may be:

1
-

Liquid as in mist, fog, clouds, or haze.

2
-

Solid as fumes, dust, fly ashes or solar smoke.

3
-

Gases as mix with the air, are dissolved in liquid droplets or
adsorbed on the surface of the suspended particles.

Aerosols differ

in several respects from other colloidal dispersion.
These differences are of importance in the destruction or
stabilization of smoke, smog and fumes.

1
-

In aqueous or colloidal solution, particles carry the same kind of
charge. In an aerosol some of the par
ticles may be positive some
are negative and some may be
uncharged.

2
-

Aerosol particles are suspended in a low


viscosity medium and
have larger "mean path", than other colloidal suspension.

3
-

The optical and thermal properties are distinctive. The particles
in
some aerosols move toward light, in others the particles move
away from the source of illumination. This phenomenon is called
"
Photophoresis
".



Soot, other solids such as iron dust, dyes, solar dust move away
from the source.



Some smoke, cigarette, aeros
ol containing transparent, liquid
droplets, sulfur and selenium aerosol move towards the incident
beam.

4
-

All aerosol are repelled by a hot object but tend to adhere to a
cold surface.

5
-


The particles in an aerosol absorb and concentrate gases and
vapors on t
heir surface.

Smoke

Smoke is an aerosol produced by incomplete combustion. It varies in
composition and properties with the fuel and oxidation condition.
Smoke from fire is different from smoke of a mechanically fired
industrial plant.

Cigarette smoke is l
argely a suspension of liquid droplets, aqueous
solutions, oil, and tars.

Soft coal and heavy oils, when burned with insufficient oxygen, produce
the dirtiest and most corrosive type of smoke.



The complex aerosol know as smoke may contain toxic gases, CO,

H
2
S under poor oxidizing conditions, and So
2
, So
3
, NO, No
2

and CO
2

in normal combustion as well as unsaturated hydrocarbon vapors
and droplets, aldehydes, peroxides, tars, organic acids, soot, dust,
fly


ash and other solid.



The
aerosol formed by the rea
ction of some of the components of
smoke with fog or water vapor has been dubbed smog. It reduces
visibility and cuts of the UV radiation. It causes eye and throat
irritation.

The primary cause of this noxious cloud was SO
2
. Today, we are more
familiar wit
h "Photochemical smog", which is formed by the reactions
of automobile exhaust in the presence of sunlight.

Automobile exhaust consists mainly of No, CO, and various unburned
hydrocarbons. These gases are called "
Primary pollutants
" because
they set in mot
ion a series of photochemical reactions that produce
"
Secondary Pollutant
s". It is the secondary pollutants


chiefly No
2

and O
3



that are responsible for the buildup of smog.

N
2(g)

+ O
2(g)



2NO
(g)

NO when release into the atmosphere

2NO
(g)

+ O
2



2NO
2(g)

oxidation



λ

< 400 nm

NO
2(g)

+
hv


NO
(g)

+ O
(g)


reactive

O
(g)

+ O
2(g)

+ M


O
3(g)

+ M M is the inert substance such as N
2


Ozone

Ozone can be formed also by a series of very complex reactions
involving unburned hydrocarbons, nitrogen oxides, and oxygen.
There is a typical
variation

with time of primary and secondary
pollutants.

NO + O
2



NO
2


{when solar radiation penetrates the atmosphere}

Ozone concentration also rise rapidly. The actual amounts depend on
the location, traffic and weather conditions, but their presence is
always accomplished by haze.



The oxidation of hydrocarbons produces dr
oplets of alcohols, and
carboxylic acids. The dispersion of these droplets in air cause
scatter of sunlight and reduce visibility and make the air look hazy.

Major efforts have been made to reduce the buildup of primary
pollutants:
-


oxidation


Co


CO
2

+ H
2
O

& unburned hydrocarbons


reduction


NO


N
2

+ O
2


&NO
2

More efficient automobile engine and better public transportation
system would help to decrease air pollution in
Urban areas.


Pt


O
3(g)

+ CO
(g)



O
2(g)

+ CO
2(g)

Prevention and Cure of air pollution

By proper combustion methods (proportion of air and vaporized fuel
must be regu
lated and four factors which must be controlled :
temperature, time, turbulence, treatment of the issuing gases.)

Cure

1
-

Low temperature catalytic returners are used.

2
-

Control of fuel composition.

3
-

Addition of smoke
-
reducing additives(ethyl nitrite and ethyl
n
itrate ).

4
-

Use Pt catalyst to convert O
3

and CO to O
2

and CO
2
.

Indoor pollution

The common indoor pollutants and radon, carbon monoxide, and carbon
dioxide, and formaldehyde.

1
-

Radon (Rn)

Rn

is a member of group 8A (noble gases), it's an intermediate
product of the radioactive decay of Uranium


238.

All isotopes of radon are radioactive, but radon


222 is the most
hazardous because it has the longest t
1/2

= 3.8 days. Radon is
generated most
ly from th
e phosphate minerals of Uranium.

226
88
Ra


222
86
Rn +
4
2
He

Radon is found in higher concentrations with Uranium, this is not
surprising, since radium is formed as a part of the stepwise decay
of uranium.

Radon is radioactive but its radiation is
not the major problem.
Since it is a gas and chemically inert, it is rapidly exhaled after
breathing. Radon decays to Polonium:


222
86
Rn


218
84
PO +
4
2
He


Polonium isotope is radioactive with long half
-
life, and is a
nonvolatile heavy metal th
at can attach itself to bronchial or lung
tissue and remain for a long time, emitting hazardous radiation.

2
-


Carbon dioxide and carbon monoxide

Both CO
2

& CO are products of combustion. CO
2

is formed in
abundant of oxygen. CO & CO
2

is

formed in a limited supply of
oxygen.



Carbon dioxide is not a toxic gas, but it does have an asphyxiating
effect. In air tight buildings, the concentration of CO
2

can reach as
high as 2000 ppm by volume (3ppm outdoor).

Workers exposed to high [CO
2
] becom
e fatigued more easily and
have difficulty concentrating. Adequate ventilation is the solution
to CO
2
pollution.



Co is a colorless and odorless gas and is highly poisonous. The
toxicity of CO lies in its unusual ability to bind very strongly to
hemoglobin.
Both O
2

and CO bind to the Fe II ion in hemoglobin
but the affinity

of hemoglobin for CO is about 200 in times greater
than that for O
2
. Carboxyhemoglobin cannot carry the oxygen
needed for metabolic processes. CO can cause drowsiness and
headache, death m
ay result when half the hemoglobin molecules
are complexed with CO. the best first aid response to CO
poisoning is to remove the victim immediately to an area with a
plentiful oxygen supply or to give mouth


mouth resuscitation.

3
-

Formaldehyde (CH
2
O)

Is a d
isagreeable


smelling liquid used as a preservative for
laboratory specimens. Formaldehyde resins are used as a bonding
agent in building and furniture materials. In addition Urea


formaldehyde insulation foams are used to fill wall cavities.

Free formal
dehyde is released under acid and humid conditions.

Low concentrations of formaldehyde in the air can cause
drowsiness nausea, headache, breathing high concentrations of
formaldehyde can induce cancers in animals, but whether it has a
similar effect in humans in unclear. The safe standard of
formaldehyde in

indoor air has been set at 0.1 ppm by volume.


oxidant

such as Al
2
O
3
/KM
n
O
4
,which converts formaldehyde to less
volatile

formic acid

(HCOOH).


Water pollution

1.

Presence of organic substances degridated by microorganisms
(food),so it consume O
2

which reduce O
2

in water that cause a
death of many animals living in water.


Microorganism + O
2

H
2
S (odour)






From nitrate




In water


2.

Factories and industrial

plants product and houses.

3.

Presence of Hg in water lead to poisonous of fish human.some
microorganism change Hg
+

to CH
3
Hg
+

soluble.

4.

Suspense particles.

5.

Radioactive isotopes from reactors which contaminate water and
underground water.


Agriculture
Pollution

1.
Animals

products reduces the O
2

in water.

2. Presence of antiseptic and fertilizer.

3.
Some chemicals taken by animals and concentrate in fats more than in
meat.

4. Rain water bring NO
3
-

and PO
4
2
-

to the water and soil.




Radiation pollution

Factories
used H
2
O hot water growth of some weeds


As coolant as blue


green weeds




Consumption



(40
0
c)


O
2


Radiation Pollution

Radioactive waste
, ionizing radiation from nuclear reactors
and nuclear
reactions produce radiation such as
α

,
β

,
γ,
neutron,this may lead

to
many reactions
that produce free radicals,electrons ,positive
species.These are all active and cause

to form new species either in air
,
solution ,water and soil.

Volcanoes

Active

volcane emits gases ,liquids,and solids.The gases include primerly
N
2
,CO
2
,HCl,HF,H
2
S and another vapors.The volcanes are the source of
two
-
third of the sulfure in the air.

At high temperature ,the hydrogen sulfide gas given off by a volcan is
oxidized by air.

2

H
2
S(g) + 3O
2
(g)

----------------
→ 2SO
2
(g) +2 H
2
O(g)


Some SO
2

is r
educed by more H
2
S

2H
2
S(g) + SO
2
(g)
-------------------
→ 3S(s) + 2 H
2
O(g)

SO
2

+ H
2
O
-------------------
→ acid rain

The mechanisim for the conversion of SO
2

to H
2
SO
4

is quite complex and
not fully understood. The reaction is believed to be initiated by the
hydroxyl radical (OH)




REFERENCE
S

1.

Iloyd A.
Munro, Chemistry in
Engineering,
PrinticeHall,Inc.,Englewood Cliffs,N.J.(1964).

2.

Robert L.Caret, Katherine J.Denniston

and Joseph
J.Topping,Wm.C.Brown
publishers,(1993).

3.

Raymond Chang, Chemistry, eighth edition, McGraw

Hill.Co.Inc (2005).