Basic of chemistry in Hindi and English both language

 Basice of chemistry 

Chemistry is that branch of science, under which the properties, composition, structure and changes occurring in substances are studied. 

 Chemistry.The word chemistry is derived from the ancient Egyptian word 'alchemy', which means black colour.  The Egyptians called black soil 'Chemi' and initially the study of chemistry was called Chemeteching.

  Lavoisier is called the father of chemistry.. Matter and its nature

  >Matter: Any object in the world which occupies space, which has mass and which resists change in its structure, is called matter. 

 Example - water, air, sand etc.  Initially, Indians and Greeks believed that all things in nature were made up of five elements, these five elements - Kshitij, Jal, Pavak, Gagan and Sameer.  

According to Kanada, the great sage of India, all matter is made up of very fine particles, which have been called 'atoms'.  

;classification of substances 

Physical classification 

solid 

liquid 

gas

Chemical classification 

pure substance                               mixture

Element  ,    / compound             1:Homogeneous 

                

Metallic     ,, / Organic                  2:Heterogeneous                  

Non-metallic,,/ inOrganic

 

Solid: That physical state of matter whose shape and volume are both fixed, is called solid.  Like iron rod, wooden chair, snowflake etc. 

 Liquid: That physical state of matter whose shape is uncertain and volume is fixed is called 'liquid'.  Such as alcohol, water, turpentine oil, kerosene etc.  It is solid liquid gas.  Example - water. 

 Gas : That physical state of matter whose shape and volume are both uncertain is called 'Gas'.  For example, air, oxygen etc.  

Note; Gases have no surface, their diffusion is very high and it can be compressed easily. 

 ::The state of any substance can be changed by changing the temperature and pressure.  But there are exceptions to this, such as - wood, stone;  They exist only in the solid state.

::  

Water can exist in all three physical states. 

:

 The three physical states of matter are in equilibrium as follows---solid---liquid---gas.  Example--‐' water.

Some substances on heating directly turn into a gas, this is called sublimation.  For example, iodine, camphor etc.  The fourth state of matter is plasma and the fifth state is Bose-Einstein condensate. 

 Element:  An element is that pure substance, which cannot be divided into two or more substances by any known physical and chemical methods, nor can it be made from the addition of other simpler substances.  For example, gold, silver, oxygen etc. 

 Compounds: The pure substances which are chemically formed by chemical combination of two or more elements in a certain proportion are called compounds. 

 The properties of compounds differ from the properties of their constituent elements, such as water.  Composed of oxygen and hydrogen, oxygen helps in burning, extinguishes the fire.  and hydrogen itself burns but the compound of these two is water.

Major elements found on earth and their percentage.

Oxygen--- 46.60%

silicon -‐-- 27.72%

aluminium‐---8.13%

Iron-----5%

calcium ‐--3.6%

potassium---2.59%

magnesium ----2.09%

titanium ----0.44%

Hydrogen ----0.14%

sodium-----2.83%

99.14 overall

Mixture: The substance which is obtained by mixing two or more elements or compounds in any ratio is called mixture.  It can be obtained again by simple mechanical method.  Like air. 

 Homogenous Mixture: A homogeneous mixture is formed by mixing the ingredients in fixed proportions.  The properties of each part of it are similar such as - aqueous solution of sugar or salt, air etc. 

 Heterogeneous Mixture A heterogeneous mixture is formed by mixing ingredients in uncertain proportions.  The properties of each of its parts and those components are different.  For example, 

gunpowder, fog etc. 

 Some major methods of separation of mixtures 

crystallisation

 : Inorganic solid mixture is separated by this method.  In this method, the impure solid mixture is heated by mixing it with the appropriate solvent and filtered through a funnel while still in the hot state.  After filtration, the solution is cooled slowly at low temperature.

  On cooling, the pure substance separates from the solution in the form of crystals.  For example, a mixture of sugar and salt is separated by this method by heating in ethyl alcohol at 348 K.

Distillation: 

 When the difference between the boiling points of two liquids is high, the mixture is separated by distillation method.  That is, it is the method of separating a mixture of liquids.  Its first part is called vaporisation and the second part is called condensation. 

 Sublimation:  By this method, a mixture of two such solids is separated, in which one solid is sublimated, the other is not.  This method separates camphor, naphthalene, ammonium chloride, anthracene, etc.

  

Fractional distillation:   By this method, such mixed liquids are separated, whose difference in boiling points is very less.  Pure diesel, petrol, kerosene, bitumen etc., from mineral oil or crude oil, are separated by this method.

  Chromatography :This method is based on the fact that different components of a mixture have different absorption capacity and they are absorbed at different distances in an adsorbent material, so that they are separated.  Types of Steam Distillation: 

This method is used to purify organic mixtures, which are insoluble in water, but volatile with steam.  Specially those substances are purified by this method, which decompose at their boiling point.  For example - acetone, methyl alcohol etc.  

Change in state of matter: 

 Melting Point: When solid substances change into liquid state on heating, this change in most of them occurs at a particular pressure and at a constant temperature;  This constant temperature is called the melting point of the object.  

Freezing point The constant temperature at which a liquid freezes at a particular pressure is called freezing point.  

Generally the melting point and freezing point of the substance are equal.  For example, the melting point and freezing point of ice are 0 ° C. 

In the presence of impurities, both the freezing point and the melting point of the substance decrease.

 Effect of pressure on the melting point. 

 1. The melting points of those substances increase with increasing pressure, whose volume increases on melting.  For example - wax, copper etc. 

2.The melting point of those substances decreases by increasing the pressure, whose volume decreases on melting;  For example - snow, cast iron etc.  

Change of volume in fusion and solidification

 Most of the crystalline substances increase in volume on melting, in which case the solid sinks in its own dissolved liquid.  Cast iron ice, antimony, bismuth, brass, etc. shrink in volume on melting, so such solids keep floating in their own throat liquid.

  Due to this special quality, a piece of ice floats in the water.  

Only these substances can be cast in the mold, which increase in volume when they become solid, because only then can they attain the shape of the mold completely. 

 Printing metals are made of such a material, which increases in volume when solidified. 

> Silver or gold coins are not molded, only stamps are made.