Chemistry

Chemistry – Materials

The branch of Chemisry that deals with the study of all the elements and the properties , preparations and applications of their compounds are called – InOrganic Chemistry
The branches of Chemistry that deals with all aspects of Carbon and its compounds are called – Organic Chemistry
The Chemistry that deals with the Theoretical and Mechanical aspects of Chemical reactions are called – Physical Chemistry
The branches of Chemistry involves the study of Chemical changes and reactions occurring with in living systems and in life process are called – Bio Chemistry
The study of constituents and their identification in Chemical subsistence is called – Analytical Chemistry
Analytical Chemistry can either be qualitative or quantitative in nature

Matter and Its Nature

Every thing in this Universe is made of materials ,which scientists have named “matter they have both mass and volume”.
Anything that occupies space and possess weight is termed matter.
The amount of matter contained in any object is known as its Mass.
Matter can neither be created nor be destroyed ,it can onlybe changed from one from to another.
Early Indian Philosophers classified matter in the form of „ 5 „ basic elements that is “ Panch Tatva”.
They are air,earth ,fire ,sky and water.
Modern Scientists classified two types based on their physical properties and chemical nature.
One way of classification of matter is into pure substances and mixtures.
Another way it is classified into elements, compounds and mixtures.

Physical nature of matter

Matter is made up of particles.
The particles are very small and have space between them.
The particles are continuously moving due to the kinetic energy.
As the temperature rises, the kinetic energy of the particles also increases ,and they move faster .
The particles of matter attract each other due to a force acting between them and keeps them together.
The strength of the force of attraction varies from one kind of matter to another

States of matter

The matter exist in three different states, such as solid, liquid and gas.
The states of matter arise due to the variation in the characteristics of the particles of matter.
The solids have a definite shape ,distinct boundaries ,fixed volumes and have neggligable compressibility.
They were difficult to change their shape.
The liquids have no fixed shapes but have a fixed volume.
Liquids flow and can change shape,they are not rigid built can be called fluid.
The solids, liquids and gases can diffuse in to liquids.
The rate of diffusion of liquids is higher than that of solids.
This is due to in liquid state,the particles move freely and have greater space between each others.
The gases are highly compressible than both solids and liquids.
The Liquified Petroleum gas (LPG) Cylinder and Oxygen supplied to hospitals in Cylender are compressed gases.
The Compressed natural Gas (CNG) is used as fuel in vehicle due to its high compressibility.
The Gases show the property of diffusion very fast in to other gases.
In the gaseous state the particles move about randomly at high speed.
The minimum temperature at which a solid melts to become a liquid at the atmospheric pressure is called its ‘melting point’ .
The melting point of a solid is an indication of the strength of the force of attraction between its particles .
The melting point of ice is 273.15k.
The process of melting or change of solid state in to liquid state is called Fusion.
Kelvin(K) is the SI unit of temperature.
0^oC = 273.15K / 273K = 0^oC
To convert a temperature on the Kelvin scale to the Celsius scale to substract “ 273 ” from the given temperature.
ie, K – 273 = Celsius
To convert a temperature on the Celsius scale to the Kelvin scale to add “ 273 “ to the given temperature. – ie , C + 273 = Kelvin
The amount of heat energy is required to change ‘1kg’ of solid in to liquid at atmosphere pressure at its melting point is known as the ‘ Latent heat of fusion’.
The particles in water at 0^oC (273K)have more energy than the particles in ice at the same temperature.
The temperature at which a liquid starts boiling at the atmosphereic pressure is known as its ‘boiling point’. It is a bulk phenomenon.
Particles from the bulk of the liquid gain enough energy to change into the vapour state.
The temperature for water to change into vapour state is 373K. ie (373 – 273^o)C = 100^oCThe water vapour at 100oC have more energy than water at the same temperature is due to the “latent heat of vaporization”.
That is particles in the steam have absorbed extra energy in the form of latent heat of vaporization .
Solid state → (heat) → Liquid state → (heat) →Gaseous state.
Solid state ← (cool) ← Liquid state ← (cool) ← Gaseous state.
The state of matter can be changed in to another state by changing the temperature.
A change of state directly from solid to gas without into liquid state is called “Sublimation”.
The direct change of gas to solid with out into liquid is called ‘deposition’ .

Change of Pressure – effect

The difference in various states of matter is due to the difference in the distance between the constituent particles.
Applying pressure can reducing temperature and liquify gases.
Atmosphere or ‘atm ‘ is a unit of measuring pressure exerted by a gas.
The SI unit of pressure is pascal ‘ pa ‘.
- 1atm = 1.01 x 105 pa.
The pressure of air is atmosphere is called atmospheric pressure.
The atmospheric pressure at sea level is 1 atm , that is normal atmospheric pressure.
The Solid Carbondioxide (Co2 ) is stored under high pressure due to the tendency to direct conversion of gaseous state on decrease of pressure to 1 atm.
Hence the solid carbondioxide is called ‘ dry ice ‘.
The pressure and temperature determine the state of a substance.

Evaporation

The phenomenon of change of a liquid in to vapours at any temperature below its boiling point is called evaporation.
The rate of evaporation increase with
- An increase of temperature
- An increase of surface area
- A decrease in humidity
- An increase in wind speed
Humidity is the amount of water vapour present in air.
If the amount of water in air is high ,the rate of evaporation decreases.
Due to evaporation clothes dry faster on a windy day.
Modern scientists talking of ‘ 5 ‘ states of matter such as,
- Solid
- Liquid
- Gas
- Plasma
- Bose Einstein Condensate.
The plasma state consists of super energetic and super excited particles.
These particles are in the form of ionised gases .
The fluorescent tube and neon sign bulbes the gases inside the bulbes get ionised and creates a plasma glowing inside.
The sun and the stars glow due to the presence of plasma in them .
In ‘ 1920 ‘ Indian Physicist Satyendra Nath Bose had done some calculation for the ‘ 5‘ th state of matter.
Based on this Albert Einstein predicted a new state of matter, that is the Bose Einstein condensate (BEC).
In 2001 Eric. A. Cornell , Wolfang Ketterle and Carl .E. Weiman of USA received the Nobel Prize in physics for achieving “ Bose – Einstein condensation”.
The BEC is formed by cooling a gas of extremely low density about one hundred thousandth the density the density of normal air to super low temperature.
One way the matter is devided in to pure substances and mixtures.
Most of the matter around us exist as mixtures of two or more pure components.
- Air – Mixture of more than 5 gases
- Petrol – Mixture of several hydrocarbons
- Drinking water – Mixture of pure water and several salts.
- Milk – Mixture of water , proteins ,vitamins ,Minerals etc
A very few examples of the use of pure substances in daily life such as
- Copper used in electrical wiring
- Distilled water in car battaries
A solution is a homogenous mixture of two or more substances.
We can also have solid solutions and gaseous solutions.
- Alloys – Solid solution
- Air – Gaseous solution
In a solution there is homogeneity at the particle level.
The major component of a solution that dissolves the other component in it is called “ the solvent”.
The minor component of a solution that is dissolved in the solvent is called “ the solute”.
In sugar solution ,water is the solvent and sugar is the solute.
Air is a Mixture of gas in gas
The main constituents of air are,
- Nitrogen – 78%
- Oxygen – 21%
The particles of a solution are smaller than 1nm/10^-9meter in diameter so they can not be seen in naked eyes.
The path of light is not visible in a solution
Depending up on the amount of solute present in a solution it can be classified in to.
- Dialuite
- Concentrated or
- Saturated solution.
At any particular temperature a solution has dissolved as much solute as it is capable of dissolving is called a saturated solution.
The amount of solute present in the saturated solution at this temperature is called its “Solubility”.
If the amount of solute contained in a solution is less than the solution level is called an Unsaturated solution.
The concentration of a solution means the amount of solute present in a given amount of solution.
There are three main ways to expressing the concentration of a solution.
- Mass by Mass percentage of solution
  = ( Mass of solute / Mass of solution ) x 100
- Mass by volume percentage of a solution = ( Mass of solute / Volume of Solution ) x 100
- Volume by volume percentage of a solution = ( Volume of solute / Volume of Solution ) x 100
Alloys are mixture of two or more metals or a metal and non – metal ,can be separated in to their components by physical methods.

Suspension

Suspension is hetrogenous mixture.
The solute particles do not dissolve but remain suspended through only the bulk of the medium.
The particles of a suspension can be seen by the naked eye.
A beem of light passing through it and make its path visible.

Colloidal Solution

A colloid is a hetrogenous mixture.
The size of particles of a colloid is too small
Colloids are big enough to scatter a beam of light passing through it and make its path visible.
They can not be separated from the mixture by the process of filtration.
A special technique of separation known as centrifugation can be used to separate the Colloidal particles.
The solute of colloid form the dispersed phase.
The solvent of colloid is known as the dispersing medium.
Colloids are classified according to the state of the dispersing medium and the dispersing phase.

Dispersed phase + Dispersing medium → Type of colloid

Liquid + Gas → Aerosol
- eg :- Fog , Clouds ,Mist

Solid + Gas → Aerosol
- eg :- Smoke , automobile exhaust

Gas + Liquid → Foam
- eg :- Shaving Cream

Liquid + Liquid → Emulsion
- eg :- milk , face cream.

Solid + Liquid → Sol
- eg :- Milk of magnesia , mud

Gas + Solid → Foam
- eg :- Foam , Rubber , Sponge , Pumice

Liquid + Solid → Gel
- eg :- Jelly , Cheese , butter

Solid + Solid → Solid sol
- eg :-Coloured gemstone , Milky glass

Different methods of separation

Seperation of the volatile component (solvent) from its non – volatile solute by Evaporation.
- eg:- Dye from Blue or Black ink

Centrifugation

Principle of centrifugation – The denser particles are forced to the bottom and the lighter particles stay at the top when spun rapidly.
This process is applied for the separation of
- In Diagnostic laboratories for blood and Urine tests.
- In Diaries and home to Separate butter from cream.
- In washing machines to squeeze out water from wet clothes.

Separation of immiscible liquids

The immiscible liquids separate out in layers depending on their densities.
Examples :-
- To separate mixture of oil and water
- In the extraction of iron from its ore.

Chromatography

It is a process of separation of components of a mixture .
‘Kroma’ means colour in greek.
This technique was first used to separation of colours .
It is mainly used for separation of those solutes that dissolves in the same solvent.
Main applications of this technique was in the separation of
- Colours in a dye
- Pigments from natural colours
- Drugs from blood

Separation of two miscible liquids

The method used is ‘Distillation’.
Its principle is that boil without decomposition and have sufficient difference in their boiling points.
If the difference of boiling points of mixtures were less than 25K ‘fractional distillation’ process is used.
Air is a homogenous mixture and can be separated into its components by “fractional distillation”
The Crystillaion mathod is used to purify solids.
It is a process that seperates a pure solid in the form of its crystals from a solution.
- Eg :- Separation of Copper Sulphate from China dish
On the basis of chemical composition substance cab be classified in to elements and compounds.
Robert Boy le was the first Scientist to use the term element in 1661
The French Chemist Antoine Laurent Lavoisier was the first to establish an experimentally useful definition of an element.
According to Lavoisier an element is a basic form of matter that can not be broken down to simpler substances by chemical reactions.
Elements can be normally divided in to follows,
- Metals
- Non – metals
- Metalloids
- Ex. of Metals – Gold , Silver, Copper, Sodium, Potassium etc
‘Mercury’ is the only metal that is liquid at room temperature.
Eg. Of non – metals – Hydrogen , Oxygen , Carbon , Iodine ,Bromine, Chlorine etc
The elements shows intermediate properties between those of metals and non – metals
are called Metalloids
Eg. of Metalloids – Boron , Silicon , germanium etc
Naturally occurring elements are ’92’ numbers.
Eleven elements are “Gaseous state at room temperature”.
Two elements are liquid state at room temperature.
- They are Mercury and Bromine.
Elements like “Gallium “ and Cesium become liquid at a temperature slightly above room temperature that is „ 303K‟.
The concentration of solution is the amount of solute present per unit volume or per unit mass of the Solution.
The dispersed phase and the dispersion medium are related to Colloids.
A compound is a substances composed of two or more different types of elements , chemically combined in a fixed proportion.
Properties of compounds are different from its
- Constituent elements
Properties of Mixtures shows properties of its elements.

Hello!