The document discusses the molecular structure of water. It explains that a water molecule is formed by two hydrogen atoms and one oxygen atom bonded together at an angle of 104.5 degrees. The polarity of the water molecule arises from oxygen's higher electronegativity which gives it a partial negative charge and the hydrogen atoms a partial positive charge. This polar nature is an important feature of water and causes it to have unique properties.

1. Name
Class
Teacher
School
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2. The water molecule is formed by the
chemical combination of 2 hydrogen
atoms and 1 oxygen atom.
• Water is essential for the existence of life.
• All bio-chemical reactions take place in a
water medium.
• Nearly 65-70% of the total body weight of
living beings consists of water.

3.  An important feature of water is
its polar nature.
 The water molecule forms an angle,
with hydrogen atoms at the tips and
oxygen at the vertex.
 Since oxygen has a higher electro
negativity than hydrogen, the side
of the molecule with the oxygen
atom has a partial negative charge.
 An object with such a charge
difference is called
a dipole meaning two poles.
 The oxygen end is partially
negative and the hydrogen end is
partially positive, because of this
the direction of the dipole
moment points towards the oxygen.
 The charge differences cause water

5. MOLECULAR STRUCTURE
OF WATER
 A molecule is an aggregation of atomic nuclei and electrons that is sufficiently
stable to possess observable properties—
 And there are few molecules that are more stable and difficult to decompose than
H2O.
 In water, each hydrogen nucleus is bound to the central oxygen atom by a pair of
electrons that are shared between them; chemists call this shared electron pair
a covalent chemical bond.
 In H2O, only two of the six outer-shell electrons of oxygen are used for this purpose,
leaving four electrons which are organized into two non-bonding pairs.
 The four electron pairs surrounding the oxygen tend to arrange themselves as far
from each other as possible in order to minimize repulsions between these clouds of
negative charge.
 This would ordinarily result in a tetrahedral geometry in which the angle between
electron pairs (and therefore the H-O-H Bond angle) is 109.5 .
 However, because the two non-bonding pairs remain closer to the oxygen atom,
these exert a stronger repulsion against the two covalent bonding pairs, effectively
pushing the two hydrogen atoms closer together.
 The result is a distorted tetrahedral arrangement in which the H—O—H angle is
104.5 . (Continued in next slide)

6. BECAUSE MOLECULES ARE SMALLER THAN LIGHT WAVES, THEY
CANNOT BE OBSERVED DIRECTLY, AND MUST BE "VISUALIZED"
BY ALTERNATIVE MEANS. THIS COMPUTER-GENERATED IMAGE
COMES FROM CALCULATIONS THAT MODEL THE ELECTRON
DISTRIBUTION IN THE H2O MOLECULE. THE OUTER ENVELOPE
SHOWS THE EFFECTIVE "SURFACE" OF THE MOLECULE AS
DEFINED BY THE EXTENT OF THE CLOUD OF NEGATIVE ELECTRIC
CHARGE CREATED BY THE TEN ELECTRONS.

7. Electrolytes
is a substance which conducts electricity either in
liquid or in solution form
Strong electrolytes Weak electrolytes
 : A strong electrolyte is  A weak electrolyte is
an electrolyte that completely an electrolyte that does not
dissociates in solution. The completely dissociate
solution will contain in solution. The solution will
only ions and no molecules of contain
the electrolyte. Strong
both ions and molecules of
the electrolyte.
electrolytes are good
Examples:
conductors of electricity.
 HC2H3O2 (acetic acid),
Examples:  H2CO3 (carbonic acid),
 HCl (hydrochloric  NH3 (ammonia) are all weak
acid), H2SO4 (sulfuric acid), electrolytes.
 NaOH (sodium hydroxide)
 and KOH (potassium hydroxide)
are all strong electrolyte.

8. 1.Strong Electrolyte -
100% dissociation,
all ions in solution
 High Conductivity
Na+
Cl-

9. Classification of electrolytes..
2.Weak Electrolyte -
partial dissociation, slight conductivity
molecules and ions in
solution
CH3COOH
CH3COO-
H+

10. Non electrolytes
A non-electrolyte does not provide ions in a solution and therefore current does not flow
through such solution.
Examples :-alcohol, carbon tetrachloride, carbon disulphide.
Non-electrolyte -
No dissociation,
all molecules in solution
no conductivity
sugar

11. Electrolysis of water
is
the decomposition of
water (H2O)
into oxygen (O2)
and hydrogen gas (H2)
due to an electric
current being passed
through the water.

12. F a r a d a y s l a ws
o f
e r la d e y c pt u t r f o r w a ryd h i si t s o
Fa a 's
o l s w
l a ws o f e l e c t r o l y s i s i n 1833.
F a r a d a y 's F i r s t La w of
El e c t r ol y s i s :
S t a t e me n t :
T h e ma s s o f a n e l e me n t s w h i c h i s
d e p o s i t e d o n a n e l e c t r o d e d u r i n g
e l e c t r o l y s i s i s d i r e c t l y
p r o p o r t i o n a l t o t h e q u a n t i t y o f
e l e c t r i c i t y wh i c h p a s s e s
t h r o u g h t h e e l e c t r o l y t e .
Ex pl a na t i on :
I f W i s t h e a mo u n t o f s u b s t a n c e w h i c h
l i b e r a t e s o r d e p o s i t e d a t t h e
e l e c t r o d e o n p a s s i n g t h e (C o n t i n u e d

13. C o n t ’d :-
As,
We c a n w r i t e t h e s t a t e m e n t o f t h e
f i r s t l a w o f e l e c t r o l y s i s
ma t h e ma t i c a l l y a s u n d e r :
o r W= Z a t
I f 1 a mp e r e e l e c t r i c c u r r e n t p a s s e s
t h r o u g h t h e e l e c t r o l y t e f o r 1
s e c o n d t h e n W=Z I t m e a n s t h a t o n
p a s s i n g t h e c u r r e n t o f 1 a mp e r e f o r 1
s e c o n d t h e we i g h t o f t h e s u b s t a n c e
d e p o s i t e d i s e q u a l t o t h e
e l e c t r o c h e mi c a l c o n s t a n t . F o r
d o i n g t h e c a l c u l a t i o n s o f
e l e c t r o c h e mi c a l p r o b l e ms , w e mu s t
k n o w t h e u n i t s t o o .
Un i t o f c h a r g e (Q ) = C o u l o m b (C )
u n i t o f m a s s (m ) = K i l o g r a m (k g )
u n i t o f c u r r e n t (A ) = a m p e r e (A )
u n i t o f e l e c t r o c h e mi c a l
e q u i v a l e n t (Z ) = k g /C

14. FARADAYS LAWS OF ELECTROLYSIS
Faraday's Second Law of Electrolysis:.
Statement:
 When the same quantity of electricity is passed through
different electrolytes, the masses of the elements liberated or
deposited are in proportion to the chemical equivalents of
these elements. Faraday's laws are very useful for the
determination of electrochemical equivalents of different
substances.
Chemical Equivalent:
 The chemical equivalent of an element is numerically equal to
its relative atomic mass in grams divided by its the valency of
the ion.
Faraday's second law of electrolysis can also be stated as
under: (Continued in next slide)

15. EXPLANATION:
TAKE THREE SOLUTIONS OF ELECTROLYTES: AGNO3, CUSO4 AND
AL(NO3)3 IN A SERIES, PASS SOME QUANTITY OF ELECTRICITY
THROUGH THEM FOR THE SAME TIME. NOW AG CU AND AL METALS
COLLECT AT THE CATHODE. THEIR MASSES ARE DIRECTLY
PROPORTIONAL TO THEIR EQUIVALENT MASSES.
ACCORDING TO FARADAY, IF 96,500 COULOMBS (OR 1 FARADAY) IS
PASSED THROUGH THESE ELECTROLYTES,
WE GET WHICH ARE THE EQUIVALENT MASSES OF
AG, CU AND AL RESPECTIVELY.

16. Applications of Electrolysis
Industrial uses
 Production
of aluminum, lithium, sodium, potassium, mag
nesium, calcium
 Coulometric techniques can be used to
determine the amount of matter transformed
during electrolysis by measuring the amount of
electricity required to perform the electrolysis
 Production of chlorine and sodium hydroxide
 Production of sodium chlorate and potassium
chlorate
 Production of per fluorinated organic
compounds such as trifluoroacetic acid
 Production of electrolytic copper as a cathode,
Hall-Heroult process for producing from refined copper of lower purity as
galuminium
an anode.

17. Electrolysis has many other uses:
Electrometallurgy is the process of reduction of metals from metallic
compounds to obtain the pure form of metal using electrolysis. For example,
sodium hydroxide in its molten form is separated by electrolysis into sodium
and oxygen, both of which have important chemical uses. (Water is produced
at the same time.)
Anodization is an electrolytic process that makes the surface of metals resistant
to corrosion. For example, ships are saved from being corroded by oxygen in
the water by this process. The process is also used to decorate surfaces.
A battery works by the reverse process to electrolysis.
Production of oxygen for spacecraft and nuclear submarines.
Electroplating is used in layering metals to fortify them. Electroplating is used
in many industries for functional or decorative purposes, as in vehicle bodies
and nickel coins.
Production of hydrogen for fuel, using a cheap source of electrical energy.
Electrolytic Etching of metal surfaces like tools or knives with a permanent
mark or logo.
Electrolysis is also used in the cleaning and preservation of old artifacts.
Because the process separates the non-metallic particles from the metallic ones,
it is very useful for cleaning old coins and even larger objects.

18. Electrolytic refining
The purest copper is obtained by
an electrolytic process, undertaken using a slab of
impure copper as the anode and a thin sheet of
pure copper as the cathode. The electrolyte is an
acidic solution of copper sulphate. By
passing electricity through the cell, copper is
dissolved from the anode and deposited on the
cathode. However impurities either remain in
solution or collect as an insoluble sludge. This
process only became possible following the
invention of the dynamo; it was first used in
South Wales in 18

19. Electroplating
• Electrotyping (also Galvanoplasty) is a chemical method for
forming metal parts that exactly reproduce a model.
• The method was invented by Moritz von Jacobi in Russia in
1838, and was immediately adopted for applications in
printing and several other fields.
• As described in an 1890 treatise, electrotyping produces "an
exact facsimile of any object having an irregular
surface, whether it be an engraved steel- or copper-plate, a
wood-cut, or a form of set-up type, to be used for printing; or
a medal, medallion, statue, bust, or even a natural object, for
art purposes.
• "[In art, several important "bronze" sculptures created in the
19th century are actually electrotyped copper, and not bronze
at all; sculptures were executed using electrotyping at least
into the 1930s.
• In printing, electrotyping had become a standard method for
producing plates for letterpress printing by the late 1800s.

21. articles made up of
cheaper metals can be
plated with gold &
silver.
By doing this the
metals appear shining
Prevents rusting of 
iron

22. Based on distinct properties, solutions can be
classified into True Solution, Suspension and
Colloid. This classification is necessary to
understand concepts of colloidal solutions and
distinguish it from rest of the types.
Solutions
 A solution is a homogeneous mixture of
two or more components. The dissolving
agent is the solvent. The substance which
is dissolved is the solute. The
components of a solution are atoms,
ions, or molecules, which makes them 10-
9 m or smaller in diameter.
Example: Sugar and Water.
Suspensions
 The particles in suspensions are larger

24. Classification of Colloids:-
One way of classifying colloids is to group them according to the phase (solid, liquid, or
gas) of the dispersed substance and of the medium of dispersion.
Dispersion Dispersed Type of Example
Medium phase colloid
Gas Liquid Aerosol Fog, clouds
Gas Solid Aerosol Smoke
Liquid Gas Foam Whipped cream,
soda water
Liquid Liquid Emulsion Milk, hair cream
Liquid Solid Sol Paints, cell fluids
Solid Gas Foam Pumice, plastic
foams
Solid Liquid Gel Jelly, cheese
Solid Solid Solid Sol Ruby glass

25. o One property of colloid systems that distinguishes them
from true solutions is that colloidal particles scatter light. If
a beam of light, such as that from a flashlight, passes
through a colloid, the light is reflected (scattered) by the
colloidal particles and the path of the light can therefore be
observed. When a beam of light passes through a true
solution (e.g., salt in water) there is so little scattering of
the light that the path of the light cannot be seen and the
small amount of scattered light cannot be detected except
by very sensitive instruments. The scattering of light by
colloids, known as the Tyndall effect, was first explained by
the British physicist John Tyndall.
o When an ultra microscope (see microscope) is used to
examine a colloid, the colloidal particles appear as tiny
points of light in constant motion; this

27. Characteristics of Suspension, Colloid and Solution
Properties Suspension Colloid Solution
1. Particle size >100nm 1-100nm <1nm
2. Separation
1)ordinary possible not possible not possible
filtration possible possible not possible
2) ultra filtration
3. Settling Settles under Settles on Does not
gravity Centrifugation settle
4. Appearance opaque Generally clear clear
5. Diffusion Not possible Diffuses slowly Diffuses
rapidly
6. Brownian motion shows shows Not
observable
7. Tyndall effect shows shows Not
observable

28. Uses of colloids:
• Purification of water by alum (coagulation)
• In rubber platting
• In tanning
• Artificial rains
• Formation of deltas (coagulation)
• Blood clot formation
• Colloidal medicine: Argyrols and protargyrol are colloidal solution of silver and are
used as eye lotions .Colloidal sulphur is used as disinfectant and colloidal gold, calcium
and iron are used as tonics. A wide variety of medicines are emulsions.
• Coating of Photographic plates
• Sewage disposal
• Metallurgy