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web4study
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PLASTICS :
Plastics are one of the types of polymers. The compounds built up of a large number of smaller molecules that have reacted with one another are called polymers. Polymer$ occur in nature as well as synthesized. Plastics belong to the synthetic polymers. The essential ingredients of these compounds are organic substances of various types
SOURCES:
The common basic raw material for synthesizing plastics are coal, petrochemicals, cotton, wood, gas, salt and water.
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Cracking:
It is the process in which alkanes of large molecular mass are highly heated in absence of air when the break-up or crack into several smaller and more valuable fragments.

 
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If two different metals are melted and then mixed together in a definite proportion, an alloy is formed.

Alloys of copper are:

(i) Bronze: It contains 90 - 95 percent copper and 5 to  10 percent tin.

(ii) Brass: It contains 60 - 80 percent copper and 20 to 40 percent Zinc.

 
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Characteristics of Halogens:
(i) The valence shell of Halogens contains seven electrons.

(ii) They have high ionization energies and large electron affinity. The accept one electron and form halide ions F1, cr1, Br1, l1

(iii) Halogens are highly reactive elements not found in the free state in nature.

 
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Aqua Regia is a mixture of 1 part of Cone. HN03 with 3 parts of Cone. HCI.

It dissolves gold (Au) due to the liberation of nascent chlorine which forms gold chloride with it, which is soluble.

HN03 + 3 HCI ---- > NOCI + 2H20 + 2CI

NOCI -> NO+CI

Au + 3CI -> AuCl3  gold chloude

 
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In this process, a mixture of pure nitrogen and hydrogen in the ratio 1 :3 by volumes are allowed to react. The basic problem in ammonia synthesis is that it is a reversible reaction and can be described as:

To get maximum yield of ammonia, the optimum condition of temperature should be 400-450°C, that of pressure should be 200-250 atmosphere and the appropriate catalyst Fe2O3 (Ferric oxide) with the small amount of Al2O3, CaO, K2O are required.
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ALLOTROPY:
The existence of two or more physical forms of the same substance or element is called Allotrope.

Two crystalline allotropes of carbon are:

(i) Diamond and (ii) Graphite

Two Amorphous allotropes of Carbon can be:

(i) Coal and (ii) Lampblack

 
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(1) Enthalpy of reaction:
The heat cooled or absorbed at constant pressure during a chemical reaction is called enthalpy of reaction.
(2) Heat of Neutralization:
The amount of heat released during a neutralization reaction in which I mole of water is formed is called at the heat of neutralization.
(3) Endothermic reaction:
The endothermic reaction is the chemical change during which heat is absorbed or taken in from the surroundings. The container becomes cold.
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Differences between Solution and Suspension:
Solution:
1. The Size of particles is between 0.1 to 1 nm.

2. Particles cannot be seen with a low power microscope 

3. It is homogeneous.

4. Particles do not settle down.

5. It is transparent.

6. Components cannot be separated by filtration. 

 
Suspension:
1. The size of, particles is larger than 1000 nm. 

2. Particles can be seen by a low power microscope. 

3. It is heterogeneous.

4. Particles settle down.

5. It is not transparent

6.
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