Wrought iron

Cast Iron

Pig iron along with scrap iron, coke and limestone is melted in a vertical furnace called cupola. Here also the carbon and other impurities present oxidise in presence of a little amount of air, to form slag. The molten iron obtained from cupola furnace can be cast into moulds. It is, therefore, known as cast iron. It consists of 93-94% Fe, 2-4% carbon and a little of S, P, Si and Mn impurities. It is vary hard and brittle. It is cast into covers of manholes, drain-pipes, frames of machines etc.'

Wrought Iron
Wrought iron is the purest form of iron containing not more than 0 • 2 peri jnt carbon and 0-3 percent of other impurities, i.e., sulphur, phosphorus, silicon and manganese.

Manufacture
It is obtained from cast iron by removing the major portion of its impurities by the well known puddling process. The cast iron along with some scrap iron is heated on the hearth of a reverberatory furnace lined with haematite. Fe₂0₃. The hot gases and flames reflected from the roof of the furnace falls upon the charge placed on the hearth. The cast iron melts down and the molten mass is stirred or puddled at intervals by means of a long pole introduced through an inlet in the wall of the furnace. The haematite supplies the oxygen required to oxidise the carbon, sulphur, silicon, manganese and phosphorus present in the cast iron.
Carbon and sulphur are oxidised to carbon dioxide and sulphur dioxide, respectively. Silicon and manganese are oxidised to silica and manganous oxide, which combine to form manganous silicate.
3Si + 2Fe₂0₃ —* 3Si0₂ + 4Fe 3Mn + Fe₂0₃ —» 3MnO + 2Fe MnO + Si0₂ —» MnSi0₃

Slag
Phosphorus is oxidised to phosphorus pentoxide which forms ferric phosphate slag with haematite.
P₂0₅ + Fe₂0₃ —* 2FeP0₄

Slag
As the impurities are eliminated, the melting point of the metal rises and iron becomes pasty. The pasty mass is stirred which forms "balls" or "blooms" which are spongy in texture due to large amounts of slag. The balls are taken out from the furnace and the slag is squeezed out by hammering. Finally, iron is rolled into sheets or forged into bars.

Wrought iron is soft, grey, tough and can be welded. It is malleable and has a fibrous structure due to the presence of thin films of slag between layers of pure iron. The presence of slag makes it extremely tough and resistant towards rusting



and corrosion. It softens at 1000°C and melts at 1530°C. It is used to make articles which are subjected to sudden and repeated stresses such as chains, anchors, wires, bolt, agricultural implements and cores of electromagnets. It has now been largely replaced by mild steel owing to its high cost.

Metric System Chart

About Metric System:

• Metric system is an International system of measurement used commonly for measuring units in the world.
• Metric system exists in various choices of fundamental units although the choice of base units does not get affected in any form.
• Metric units are used universally in scientific work around the world for all forms of personal and commercial purposes.
• Standard set of prefixes in powers of ten are used to derive larger and smaller units from the base units.
• Goal of the metric system is to prescribe a single unit for every physical quantity so as to avoid the need for conversion factors.
• Meter is the basic unit used to measure lengths and distances. This unit is converted to many other units such as inches, feet, yards, fathoms, rods, chains, furlongs, miles, nautical miles, leagues, etc.
• Early metric system includes several fundamental or base units and other quantities are derived from the base units. For example the basic unit of speed is calculated as meters per second.
• The metric system is also called as decimal system because all multiples and sub multiples of the base units are basically factors of powers of ten.
• In a formal representation fractions are not used to represent Metric units.

Advantages of a decimal system:

• They substitute other non-decimal systems too apart from metric system of measurements.
• All derived units use a set of prefixes for each multiple such as kilo for mass (kilogram) or length (kilometer) both indicating a thousand times the base unit.

Metric System Chart

Quantity	Unit	Symbol
Length	Millimeter Centimeter Meter Kilometer	mm cm m Km
Mass	Milligram gram Kilogram Ton	mg g Kg T
Time	Second	s
Temperature	Degree Celsius	oC
Area	Square meter hectare square kilometer	m2 Ha Km2
Volume	Millimeter cubic centimeter liter cubic liter	ml cc L Cl
Speed	Meter per second Kilometer per second	m/s km/s
Density	Kilo gram per cubic meter	Km/cc
Force	Newton	N
Pressure	Kilo Pascal	K Pa
Power	Watt, kilo watt	W KW
Energy	Kilo joule, mega joule	KJ MJ
Current	ampere	A

Prefixes used in Metric System Units

Giga	G	109
Mega	M	106
Kilo	k	103
Centi	c	10-2
Milli	m	10-3
Micro	μ	10-6
Nano	n	10-9

Pig iron productions

Introduction :

Pig iron is the intermediate product which is obtained during the smelting of iron ore with coke, in this process limestone is used as flux. Pig iron has maximum carbon content, it is around 3.5–4.5% which improves the brittleness of iron. In olden days, the Chinese Zhou dynasty were making pig iron in Europe. The plant used for the pig iron production is sinter plant.There will be use of two furnaces for the pig iron production. The word pig iron comes from old casting blast furnace iron method into moulds which are arranged on the beds of sand.

Pig iron production:

Blast furnace used for pig iron production:

Pig iron production is done by blast furnace method which involves the smelting of iron ore like hematite, i.e.
Fe₂O₃ + 3CO → 2Fe + 3CO₂

A blast of preheated air is blown through the furnace which reacts with carbon which is in the form of coke to produce carbon monoxide and also a large amount of heat is produced. The produced carbon monoxide reacts with the iron ore to form molten iron and carbon dioxide. Unreacted carbon monoxide, nitrogen which is present in the blown air and hot carbon dioxide are fed into the reaction zone as a fresh feed so that there will be preheating of fresh feed using counter current gases and also there will be the decomposition of limestone to calcium oxide and carbon dioxide and starts to reduce iron oxide in the solid state. So formed calcium oxide reacts with some of the acidic impurities which are present in iron which form a slag called calcium silicate. The reactions involved in the pig iron production are

C + O₂ → CO₂
CO₂ + C → 2CO
CaCO₃ → CaO + CO₂
SiO₂ + CaO → CaSiO₃(slag)

The pig iron obtained by this method has high carbon content so which increases the brittleness by that it has limited commercial applications. If there is a need to reduce the carbon content, pig iron undergoes further processes.

Applications of Pig iron:

• Pig iron sometimes used to produce cast iron and Gray iron which is achieved by smelting the pig iron.
• Pig iron is used to produce steel metal.

Iron Steel Manufacturing

Introduction :
Iron produced in the blast furnace is known as pig iron or cast iron.  Pig iron is the iron which contains 4% of carbon and some other impurities.

Carbon contents present in pig iron are reduced by burning off carbon as carbon monoxide and carbon dioxide. Impurities present as sulphur, manganese etc are oxidised as their oxides. There are three methods of burning carbon for production of steel.

(i) Bessemer Process
(ii) Open Hearth Process
(iii) Electric Furnace Process

Bessemer Process of Manufacturing:

This was the first process for the mass-production of steel from molten iron. Henry Bessemer invented this process in 1855.

Principle: Removal of impurities from iron by oxidation is the key principle of this process. The oxidation also raises the temperature and hence melts the iron.

Process: In this process, burning takes place in a pear shaped furnace called Bessemer Converter. This furnace is coated with basic mixture of calcium oxide or magnesium oxide (CaO / MgO). Hot air is introduced through holes. The temperature of furnace is maintained at 1873K. Manganese in the iron is removed as manganese silicate, (which is called as slag).

2Mn + O₂ ----------> 2MnO

Si + O₂ -----------> SiO₂

MnO + SiO₂ -----------> MnSiO₂

Phosphorus present as impurity is removed by formation of slag. This slag is called Thomas slag. Thomas slag is very useful fertilizer.

4P + 5O₂ -----------> 2P₂O₅

3CaO + P₂O₅ -----------> (Ca)₃(PO4)₂    Thomas Slag

Open hearth process of manufacturing:

This process can be used for rapid manufacture of large quantities of steel. The steel producd by this process can be used for the construction of the high buildings. This process complemented the Bessemer process to produce steel. It is easier to control because it is a slow process.
In this process, cast iron, iron scrap, haematite and lime is taken in open hearth furnace. This furnace is heated at temperature of 1873 K. This furnace is heated with (CO+N₂). (CO+N₂) is called producer gas. Impurities are removed by oxidation with haematite.

Fe₂CO₃ + 3C ----------> 2Fe + 3CO

2Fe₂O₃ + 3S -----------> 4Fe + 3SO₂

5Fe₂O₃ + 6P ------------> 10Fe + 3P₂O₅

2Fe₂O₃ + 3Si ------------> 4Fe + 3SiO₂

3CaO + P₂O₅ ------------> Ca₃(PO4)₂ (Slag)

Electric Arc Furnace

 In this method, iron is heated electrically. Normally thesedays, steel is prepared by open hearth process. About 39% of the steel manufactured in US is produced from the electric furnace. The stel produced by this process is not very pure or of high quality.

Energy Consumption: An electric arc furnace consumes an energy of 350 - 700 kWh/ton of steel produced. We can reduce the energy consumption to 425 kWh/ton by using oxy-fuel burners.
This process is used for the electric production of steel. It is used for remelting of steel scrap. This process is useful for those markets where the quality of steel is not critical.

Air speed

Introduction :
It is the speed of an air related to the aircraft among them the qualifying airspeed are Calibrated airspeed, Indicated aircraft, Equivalent air speed, true airspeed and finally the density airspeed. This aircraft speed is measured by the airspeed indicator which is shortly and popularly known as ASI. These are connected to the pitot static system. Types of the airspeed are Indicated airspeed, Calibrated airspeed, Equivalent airspeed, True airspeed. In this article we will know types of articles and how to calculate the airspeed.

Air speed Types

Indicated airspeed is abbreviated as IAS. This indicator reads directly form the airspeed indicator by the pitot static system on the aircraft. This is the airspeed related to the CAS that is calibrated airspeed it is corrected for the installation errors and the instrument.

These IAS are very much important for the pilots for the various purposes like calculation of the limited speeds and so on. This plays an important role in the airspeed.

Calibrated air speed is for the instrument errors and position errors and the installation errors. This equation shows the installation and the minus position.
Where, Vc is the calibrated airspeed
qc is the impact pressure
Po is static air pressure. Measures 29.92126 inches Hg at sea level.
ao is speed of sound. Measures 661.4788 knots at standard sea level.

Equivalent & True airspeed

Equivalent airspeed: This produces dynamic pressure as the true speed at the altitude where the vehicle is flying. It is forward to the flight for the effects of compressibility. Compressible impact pressure makes a function of calibrated airspeed. At standard sea level equivalent airspeed and calibrated airspeed are equal.

True airspeed is also called as TAS, it is the physical speed of the aircraft. The relation between true airspped and speed is Vg.
Vt = Vg - Vw
Where Vw is the wind speed vector.
To compute true airspeed using a function of mach number
V_{t =} a_o.M`sqrt(T/(To))`
Where:
a_o= Speed of sound(661.4788 knots) at standard sea level
M = Mach number
T = Temperature in kelvins
T_o= (288.15 kelvins)Standard sea level temperature

Speed of Light and Sound

Introduction :

Light and sound are the essential part of our life and with an absence of one; we will not be able to communicate or to detect properly as we can do with help of these two. Light and sound both are the sensations produced by energetic particles with the help of which we will be able to see or listen. 

Difference between Speed of Light and Sound :

Regarding the speed of light and sound we can say the following points

1. Speed of light is much faster than the speed of sound in air.
2. Light do not require the medium to travel with its speed while the sound require medium to propagate.  
3. Speed of light is much less in transparent than what it had in vacuum.  While the speed of sound is much, fast in solid medium such as steel then in air.

Speed of light and sound : Conclusion

Why speed of sound Differ in different mediums means solid, liquid and air?

Explanation:
Since sound require medium particles to propagate properly, hence the medium having particles much closer will enhance the movement (speed) of sound wave rather than the medium which have a long gap between the particles. Since, the molecules spacing for solid, liquids, and gases are different in that gas molecules are more spread apart & free to move, liquids are a little more structured, and solids are very compact.             

The other reason for the different speed in different mediums is the elasticity of the medium. More the elasticity in the medium more will be the speeds of sound as we can understand with ball, more the elasticity of the ball more will it jump. Since steel is more elastic than air, so sound travels 19 times much faster in steel than its speed in air. E.g. if we put your ear on rail track we can hear the vibration of the train movement in the track much before than the whistle of the train which travels through air.

Aircraft speed of sound

Introduction :
Air crafts with propellers in the initial stages were not able to perform well when they approached the speed of sound. This problem resulted into deep research into jet engines conducted mainly by Frank White of England and Hans van Ohain of Germany. They carried out this research in their respective countries.

Breaking Sound Barriers

Various sources claimed to have broken the sound barriers. Claims were made that air crafts ran smoothly at the speed of sound without any turbulence but there were many disputes against these claims. These claims were made as early as 1945. Man has attempted to break the sound barriers since the time the first plane was invented by the Wright Brothers. Bell X-1 was the first flight to travel faster than the speed of sound and this happened on 14^th October, 1947 under Captain Charles Yeager.

Speed of Sound

The exact speed of sound is not known but it is considered that it varies according to the height above sea level or what we call as altitude. It is 761 mph at sea level and at 20000 feet above it is 660 mph.

Modern Aircrafts and their speed

Today there are several air crafts like fighter jets that travel at speeds faster than the speed of sound regularly. When the aircraft reaches close to the speed of sound what happens is quite interesting in respect of the movement of air around the wings of the plane. It is called the Prandtl-Glauert singularity and it is quite photogenic.

Conclusion to aircraft speed of sound

In two decades ranging from 1947 to 1967 there were appreciable efforts by man to reach the speed of sound and there are crafts that are unmanned and cross the speed of sound easily and that is quite a remarkable achievement. There will be further developments and we all have to wait and watch how fast air crafts will become.

Orbital Speed

The orbital speed of a celestial body measures its speed around another object’s center of gravity. This can be its speed at a given time and place in its path or may be its average speed. Depending upon the eccentricity of heavenly body's orbit the orbital speed changes as a satellite or moon gets closer to its center of gravity or further away. The two regions where speeds can change the most are pericenter and apocenter.

A satellite in orbit moves faster (pericenter) when it is close to the planet or other body that it orbits and slower (apocenter) when it is farther away. A satellite moving in a circular orbit has a constant speed which depends only on the mass of the planet and the distance between the satellite and the center of the planet.

Calculating the Orbital Speed

The speed (v) of a satellite in circular orbit is:

`v = sqrt((GM)/r)`

Where, `G` is the universal gravitational constant and the value is `6.6726 xx 10^-11 N m^2 kg^-2`,
`M`  is the mass of the combined planet-satellite system, in case Earth's mass is `5.972 xx 10^24 kg`, and we can ignore the satellite's mass, in case for smaller man made satellites.
and `r` is the radius of the orbit measured from the planet's center.
The period `P` of a satellite in circular orbit is the orbit's circumference divided by the satellite's speed:

`P = (2*pi*r)/v`

Kepler's Law for Orbital Speed:

Kepler's second law is illustrates that the line joining the Sun and planet sweeps out equal areas in equal times, this means the planet moves faster when it is nearer the Sun (perihelion). Henceforth, a planet executes elliptical motion with constantly changing angular speed as it moves about its orbit. The point of nearest distance of the planet to the Sun is known as perihelion; the point of greatest separation is known as aphelion. Therefore, by Kepler's second law, the planet moves fastest when it is near perihelion and slowest when it is near aphelion.

Arrhenius theory acid

Introduction :
According to Arrhenius an acid  is any substance that dissociates   to give  a H+ ion  in aqueous solution.

Thus an aqueous solution of hydrochloric acid will  show the presence of H+ ions and Cl- ions.
 Later it was found that the H+ ions have no free existence in water or in aqueous solution but exist in the solvated state as hydronium ion as H₃O^+.

  Thus according to Arrhenius definition of an acid,  any substance that will increase the concentration of H+ ions in water is said to be an acid.

  General Representation:  An Arrhenius acid  is generally represented by the formula with a H in the begining as HCl , H₂SO4 , HNO_3. All  acids that can donate a proton in aqueous solution or  can increase the concentration of H₃O⁺ ions in solution  are called Arrhenius acids.The dissociation of an acid in water can be represented by the equation a follows:
 If HCl be the acid then the dissociation is given as
HCl((g)  +  H₂O(l)    ---> H₃O⁺  + Cl^-

The advantage of the Arrhenius definition of an acid.

1) All protic acids that can dissociate in aqueous solution to increase the H+ ione concentration show similar properties such as :

Reaction with bases result in neutralisation of the acid and formation of water and a salt
example: HCl + NaOH----------> NaCl + H₂O
                  HNO₃ + KOH --------> KNO₃ + H₂O      

2)  The basicity of the acids depends upon number of H+ ions, an acid can releas in aqueous solution

3) The pH of any substance depends upon the number of H+ ions the substance can release in solution

Limitation of Arrhenius definition of acid>

1) Arrhenius definition of acid holds good only for acids in aqueous solution. For example
HCl (aq) ----------> H⁺(aq)  + Cl^- (aq)
      H⁺ (aq) + H₂O (l) ---------> H₃O⁺ (aq)
    But HCl in gaseous state is neither acidic nor basic.

2) Acid not dissolved in (aq) solution cannot dissociate into H+ ions. For example
     HNO3 (l) + 2H2SO4 (l) -----------> NO⁺⁺ (l) + H₃O⁺ (l) + 2HSO₄^-   (l)
Here HNO3 acts as a base

3) Arrhenius definition of acid cannot account for the acidic character of AlCl₃

Learn definition of sec

Introduction :
Learn definition of Sec is defined as the function which is used to calculate the ratio of sides of the triangle. It is also known as inverse of cos function. Sec is a one kind of trigonometric functions. Sec of an angle is the ratio of hypotenuse and the length of the adjacent side. In other words, the learn definition of Sec is the reciprocal of cos.

In a right angle triangle,

                  Sec(A)=hypotenuse       
                              adjacent side        
               Here A is a angle, Sec (A) = 1/ (cos A)        

Learn definition of sec:

Learn properties of sec angle:
Learn definition of sect is intervallic and repeats itself every 2 radians. An essential property is sec(0)=1. Few other main properties are

By the definition of sec,
           sec x               = 1/cos x
           sec( x + 2 )   = sec (x) sec ( /2)    = ∞ (infinity)
           sec(-x)            = sec(x)
           sec(x)             = i sec h(ix)

Learn important calculus relations of sec:
             d/dx sec(x) = sec(x) tan(x)    (differentiation)
            ∫ sec(x) dx   = ln sec(x) + tan(x) = ln ( /4 + /2)  (integral)

Learn series expansion of the function of sec:
           sec(x)  = 1 + x²/2 + 5x⁴/24 + 61z⁶/ 720 + ..... + (-1)ⁿ E_2n/(2n)! X_2n + ......
Here the E's are the Euler numbers of secant.

Learn domain of sec:
          Every numbers are real except /2 + k , k is an integer.

Learn range of sec:
           (-∞ , -1] U [1 , +∞)

Learn Period of sec:
                 2 π

Learn y intercepts of sec:
           y = 1

Learn of sec symmetry:
           sec(-x) = sec (x).   Because sec (x) is an even function and graph is symmetric.

Learn of sec intervals of increase/decrease:
From 0 to 2, sec (x) is increasing on (0 to /2) U ( /2  to  ) and decreasing on ( to 3 /2) U (3 /2 to 2 ).

Learn vertical asymptotes of sec:
           Vertical asymptote = /2 + k π , where k is an integer.

Learn co function for sec : 
           sec x  = cosec (90^o - x).

Practice problem for learn definition of sec:

Practice problems using learn of secant function:
1. Find the function value of sec 45^o.

Solution:
         Use the Sec's co task identity to solve the problem.
By the definition of sec,
        function for sec is  sec x   = cosec (90^o - x)
                                         sec 30^o= cosec (90^o – 30^o )
                                                      = cosec (60^o)
                                          sec 30^o = 0.866
         The solution of sec of 30^o is 0.866.

2. Find the angle of a right triangle where hypotenuse = 2, length of the adjacent side = 1 using secant function?

  Given:
         In a right angle triangle length of the hypotenuse = 2, length of the adjacent side = 1

  Solution:         
By the definition of sec,
           Sec x  =  hypotenuse/adjacent side
                      = 2 / 1
                   x = sec^-1 (2)
                   x = 60^o 
The secant angle of triangle is 60 degrees.

Electricity sources

Introduction :

Electricity is the main branch of physics, which deals with the motion of the charges. The device which produce electricity or which can convert one form of energy into another form is called the sources of electricity.The sources of elecricity can be had from nuclear plant,  fossil fuels like coal, natural gas etc. Even the solar radiation can be used to obtain electricity.Here we discuss the sources of electricity.

About Electricity sources

Electricity is the very important form of energy, which we use, in our daily life. Now these days we even do not imagine the life in the absence of electricity. The sources of electricity are cells, which are very common and very convenient in use. There are two types of the cells one are called the primary cells and t0he other are called the secondary cells. The primary cells are those, which cannot be recharged, and the secondary cells are recharged several times up to some limit. Voltaic cell is the most important type of the source of electricity.

It is the simplest form of the electrochemical cell. It consists of a glass vessel containing dil. sulphuric acid. Copper and the zinc rod are dipped in the dil. Sulphuric acid. These copper and zinc rods are called the electrodes. When the bulb of a torch is connected across the electrodes through a conducting wire, it glows that means the electricity is produced due to some chemical reaction. When sulphuric acid dissolved in water, it decomposes into ions as shown in the reaction given below

H2SO4       `->`         2H+ + SO4 2-

Zinc atoms from zinc plate begin to dissolve slowly in H2SO4 in form of Zn2+. Each zinc atom dissolved in H2SO4 from the Zn plates leaves two electrons on the Zn plate. This zinc plate becomes negatively charged.

Zn (in solution)        `->`        Zn 2+   + 2e- (on Zn plate)

The potential acquired by the Zn plate is – 0.62 Volt. When Zn ions enter the solution from the Zn plate, an equal number of H+ leaves the solution and deposit on the copper plate. The hydrogen ions get electrons from the copper plate to become neutral hydrogen atoms.

H+ + e -    `->`            H

A pair of hydrogen atom combines to form the hydrogen molecule and the bubbles of the hydrogen gas are formed. Copper plate becomes positively charged and the potential is 0.46 Volt. So the potential difference of the voltaic cell is 0.46 – (-0.62) = 1.08 Volts.

Conclusion of the electricity sources

Thus, we observed that the same potential difference is developed across the plates of the cell. That means there are some free charges, which are in motion. As we connect a resistance in the path of the free charges, it will move and the electricity is produced so that the current flows through the bulb and it will glow.

How does electricity works

Introduction:

The basic electrical circuits consists of the following ;

The Source which generates power such as a generator,

the load which utilizes the power,

and two wires to carry the electrons act as conductor from the power source and back to power source.This is how the electricity will works.

                                        how does electricity works

Measure of electricity or power is Watts and Kilowatts.

Watts = (Volts X Amps).

Electron: In order to understand electrons, we need to have a understanding of the atom. Atom consists of  a nucleus(having protons and neutrons)  and electrons revolving around it in circular orbits.

How does electricity works

Current: Movement of charge carriers (electrons) from one place to another place is called as current.

One amp is defined as one coulomb of charge carriers passed through a cross section of conductor per unit time.That is  6.28 x 10^18 electrons per second.

Voltage: It is the electrical force that gives the energy to free electrons to move from one atom to another. Just as water needs some pressure to force it through a pipe, electrical current needs some force to make electron flow. "Volts" is the unit of measurement of "electrical pressure" that causes current flow. Voltage is also called as potential difference between two points along a conductor.

Load: Load is the one which consumes the generated energy

 The power source generates the voltage which force the electrons to flow through the conductors when load is connected and it is a closed loop. The load utilizes the power to convert electrical energy to some other form.

Importance of electricity:

Electricity is  life blood that flows in our society. Our survival based on electricity. Electricity generates in several forms. Electricity most basic generated form is lightning. Portable devices like torches,mobiles use batteries which is a form of static electricity.Sun is also one of the major source of electricity if we convert the radiated light energy to electricity with the help of photocells.

The very fundamentals of electricity starts with electrons. Electron flow depends upon the type of material . Some materials do not allow electrons to move through it freely from one atom to another, those type of materials called as Insulators. Some materials allow free flow of electrons those are good conductors of electricity called as conductors. The movement of electrons referred as current.

Electrons can freely move in conductors then why we need voltage ?

 Conductors having the movement of electrons in a random direction in order to make the the electrons to flow in a particular direction we need to impart energy for the electrons that energy is called as Voltage. We can compare this two terms with a dam having potential head as voltage and the stream of water flow can be compared with electron flow. The more the potential head in the dam the larger will be the flow of water.

A battery works in the similar way it is having two terminals, a positive terminal and a negative terminal. The source, whether may be generator or battery, will push the electrons to the negative terminus. The rate at which it pushes the electrons is the voltage. The equipment, electronics appliances you that will consume electricity  is called the load. The electrons will leave the negative side of the power source, energize the equipment, and flow to the positive side of the power source.

Resistance: It is the force that resists the flow of electrons.. The units of resistance Ohms..

OHM’S LAW:Ohm’s law  state that voltage  (V) in a circuit is directly proportional to the , current or amps are (I) .

 V=IR.

In  a light bulb. The thin wire inside  the bulb is called filament. When power is applied to the bulb, the tungsten filament resists the flow of electrons. We can calculate that resistance by Making Resistance as subject of formula, r=V/I. So a 60 Watt light bulb’s resistance would be 240 Ohms.

There are basically two types of electrical currents,
    Direct current (DC)

   Alternating current (AC).

Direct current :Here the magnitude of the current is constant through out the wave form .Example battery  produces the DC current that flows in one direction only that is moving directly from the negative terminal to the positive terminal of the battery.

Alternating current: The magnitude of the current continuously varies with time.Example of AC power sources Generator.The magnitude is varying with time so frequency comes into picture. Frequency can be defined as the number of cycles produced in a given unit of time.This is called Hertz (Hz) or Cycle.

How does electricity works

Advantages:

The advantage of alternating current is that from  power  generating stations send millions of volts from their power plants through small conductors to transformers that will step down to required voltages in the distribution end.

Fcc unit cell

Introduction to unit cell
A regular three dimensional arrangement of points in space is called a crystal lattice. A unit cell is the smallest of a crystal lattice which, when repeated in different directions generates the entire lattice

Face centered cubic unit cell

A face centered cubic unit cell contains atoms at all the corners and at the centre of all the faces of the cube. Each atom located at the face centre is shared between two adjacent unit cells and only half of each atom belongs to a unit cell. Thus, in a face centered cubic unit cell:

1. 8 corners atoms × 1/8 atoms per unit cell=1 atom
2. 6 face centered atoms × 1/2 atoms per cell=3 atoms

Therefore, total no. of atoms per unit cell = 4 atoms

Packing efficiency of fcc unit cell

Packing efficiency is the percentage of total space filled by the particles. Let us calculate the packing efficiency of fcc unit cell. Let the unit cell edge be ‘a’  and face diagonal be ‘b’.
We know that b=√2a
If r is the radius of the sphere, we find
    b = 4r =√2a or a = 2√2r
we know that each unit cell in fcc structure, has effectively 4 spheres. Total volume of four spheres is equal to 4×(4/3)πr³ and the volume of the cube is a³ or (2√2r)³.
Therefore,
Packing efficiency of fcc unit cell
=volume of 4 spheres ×100/volume of unit cell  %
=4×(4/3)πr³×100/(2√2r)³
=74%

Density of unit cell

Volume of unit cell = a³
Mass of the unit cell =number of atoms in unit cell×mass of each atom
=z × m
Where z is the number of atoms in unit cell and m is the mass of single atom.
Mass of an atom present in a unit cell:
    m = M/N_a   (M is molar mass)
therefore, density of the unit cell =mass/volume
         =z×m/a³ = z×M/a³×N_a
     d   =    zM/a³N_a

Summay

The number of atoms in a fcc unit cell is four and these are present at all corners as well as at the centre of all faces of the cube

Make a fuel cell

Introduction :
A Fuel Cell is a device that converts the energy of the chemical reaction between a fuel and an oxidant into electricity and heat.  It is easy to make a fuel cell working, by using an anode, cathode, catalysts and most often an electrolyte.  Fuels and oxidants are also necessary to make a fuel cell.  Fuel cells are combined into groups to obtain a usable voltage and power output, called stacks. Fuel cells generate electricity electrochemically, rather than mechanically, so they are more efficient over a wider load factor and can cut greenhouse gases by over 50 percent.  Fuel cells are very much different from batteries. Fuel cells consume reactant from an external source, which must be replenished.  Fuel cells produce electricity with an efficiency of about 70 % compared to thermal plants whose efficiency is about 40%.

How to make a fuel cell

We can make a fuel cell (Hydrogen Fuel Cell) in our kitchen in just 10 minutes, and demonstrate how hydrogen and oxygen combines to give clean electricity.
To make a fuel cell, we would need:

• One foot of platinum coated nickel wire along with small piece of wood or Popsicle stick.  
• A 9 volt battery clip and a 9 Volt battery.
• A little transparent sticky tape.
• One glass full of water.
• Volt meter device.

Hydrogen-oxygen Fuel cell

One of the most successful fuel cells uses the reaction of hydrogen as fuel and oxygen as oxidant to form water (Hydrogen oxygen fuel cell).  The cell was used for providing electrical power in the Apollo space programme.  The water vapors produced during the reaction were condensed and added to the drinking water supply for the astronauts.  In the cell, hydrogen and oxygen are bubbled through porous carbon electrodes into concentrated aqueous solutions of sodium hydroxide.  Catalysts like finely divided platinum or palladium metal are incorporated into the electrodes for increasing the rate of electrode reactions.

Catalysis plays a very important role in Hydrogen oxygen fuel cells, separating the electrons and protons of the reactant fuel (at the anode), and forcing the electrons to travel though a circuit, generating electrical power.  At the cathode, another catalytic process takes the electrons back, combining them with the protons, which have traveled across the electrolyte and the oxidant to form waste products like carbon dioxide and water.
The electrode reactions of Hydrogen oxygen fuel cell are given below:
Cathode reaction:     O₂ (g) + 2H₂O (l) + 4e⁺    4OH^–(aq)
Anode reactions:       2H₂ (g) + 4OH^–(aq)  4H₂O (l) + 4e^–
Overall reactions:     2H₂ (g) + O₂ (g)   2 H₂O (l)
The cell can run continuously as long as the reactants are supplied.

Alcohol fuel cell

Introduction

A fuel cell is an electrochemical device which converts the chemical energy of compounds into electrical energy via electrochemical reactions. Unlike a conventional battery, a fuel cell is not an energy-storing apparatus but reactants are continuously replenished into the cell separately during the operation. A Hydrogen rich compound or pure hydrogen is used as a fuel, while oxygen from the air or pure oxygen commonly serves as oxidant. The benefits obtained using a fuel cell for energy production are high efficiency and low emissions of harmfull effluents.

Alcohol fuel cell

In an alcohol fuel cell, as the name indicates alcohol is used as a fuel to produce electricity.  The cell in which Methanol is directly used as fuel is named as Direct Methanol Fuel cell. The technology behind Direct Methanol Fuel Cells (DMFC), a particular example for alcohol fuel cell.  It is still in the early stages of development, but it has been successfully demonstrated powering mobile phones and laptop computers—potential target end uses in future years.

In the early 1990s, DMFCs were not appreciated because of their low efficiency and power density, as well as other problems. Improvements in catalysts and other recent developments have increased power density to 20-fold and it is expected that the efficiency may eventually reach 40%.

DMFC is very similar to the PEMFC in that the electrolyte is a polymer and the charge carrier is the hydrogen ion (proton). However, in a DMFC, the liquid methanol (CH₃OH) is oxidized in the presence of water at the anode generating CO₂, hydrogen ions and the electrons that travel through the external circuit as the electric output of the fuel cell. The hydrogen ions travel through the electrolyte and react with oxygen from the air or pure oxygen, used as oxidant and the electrons from the external circuit to form water at the anode completing the circuit.

Cell reactions

Reaction at the Anode:      CH₃OH + H₂O => CO₂ + 6H+ + 6e^-
Reaction at the Cathode:   3/2 O₂ + 6 H⁺ + 6e^- => 3 H₂O
Overall Cell Reaction:       CH₃OH + 3/2 O₂ => CO₂ + 2 H₂O

These cells have been tested to work in a temperature range from about 50ºC-120ºC. This low operating temperature and advantage of no requirement for a fuel reformer make the DMFC an excellent candidate for very small to mid-sized applications, such as cellular phones and other consumer products, up to automobile power plants.

One of the drawbacks of this alcohol fuel cell is that the low-temperature oxidation of methanol to hydrogen ions and carbon dioxide requires a more active catalyst, which typically means a larger quantity of expensive platinum catalyst is required than in conventional PEMFCs.

One other demerit of driving the development of alcohol fuel cells is the fact that methanol is toxic. Therefore, some companies have been developing the advantageous Direct Ethanol Fuel Cell (DEFC). The performance of the DEFC is currently only about half that of the DMFC, but this gap is expected to narrow within very short time.

Diagram of atom structure

Introduction :
Atom is defined as the very small particle. The atoms are having many chemical properties of the elements. The atoms structure are having the nucleus at its center. The electrons are also present in the atom. The electron is always surrounds the nucleus part. The particles like protons and neutrons are also present in the atom.

Various particles present in the diagram of an atom structure

The atom diagram structure consists of three types of particles. They are defined below the following,
1. Protons
2. Neutrons
3. Electrons

Explanation for the various particles for the diagram of atom structure

The diagram of Structure of an Atom is shown below,
                 

Protons:
The protons present in the atom are having a positive charge. The positive charge is equal to the negative charge present in the electrons. The number of particles present in the atoms is used for the representation of the atomic number. Protons are 1836 times greater than the electrons. The proton structure is discovered by the scientist named Ernest Rutherford.

• The mass of the proton is given by 938 MeV/c² = 1.67 x 10^-27 kg.
• The charge of the3 proton is given by 1.602 x 10^-19 Coulombs.
• The diameter of the proton is given by 1.65 x 10^-15 m.

Electron:
The electrons are having the negative charges. The electrons cannot able to split into the further particles. The electrons move freely in the diagram of an atom. The electron forms the electron clouds.

• The mass of an electron present in the atom is given by 9.2095 x 10^-31 kg.
• The charge of an electron present in the atom is given by -1.602177 x 10^-19 C.
• The electron rest energy present in the atom is given by 0.511 MeV.
• The spin of an electron present in the atom is given by + `(1)/(2)` or -`(1)/(2)`

Neutron:
The charge of the neutron present in the atom is having neutral charge. The neutrons present in the atom are used to represent the isotope of the element.

• The mass of the neutron is given by 1.67492729 × 10⁻²⁷ kg.
• The charge of the neutron is given by 0.  
• The spin of the neutron is given by `(1)/(2)`

Classification of Chemical Coordination

Introduction:

A metal or coordination complex is a structure which consist of a central atom or ion which is usually a metal being bonded to a molecules or anions array. Examples are ligands and complexing agents. Within a ligand, there is an atom that is directly bonded the atom in the centre or ion, this is called the donor atom. A chelate complex can be formed by polyadenylated ligand. At least one pair of electrons is donated by the ligand to the central atom/ion.

Compounds containing a coordination complex are called coordination compounds. The central atom or ion together with all ligands forms the coordination sphere.

Coordination points to the "coordinate covalent bonds" (dipolar bonds) between the ligands and the central atom.

Classification of Chemical Coordination

Metal complexes also known as coordination compounds; they consist of all metal compounds, aside from metal vapors, plasmas, and alloys. The study of "coordination chemistry" is the study of all alkali and alkaline earth metals, transition metals, lanthanides, actinides, and metalloids. Thus, coordination chemistry is the chemistry of majority of the periodic table. Metals and metal ions only exist in the condensed phases surrounded by ligands.

The different areas of coordination chemistry are classified according to the nature of the ligands. They are:

 1) Classical (or "Werner Complexes"): Ligands in classical coordination chemistry bind to metals via their "lone pairs" of electrons residing on the main group atoms of the ligand. Typical ligands are H2O, NH3, Cl−, CN−, en−

Examples: [Co(EDTA)]−, [Co(NH₃) ₆]Cl₃, [Fe(C₂O₄) ₃]K₃

2) Organo-metallic Chemistry: Ligands which are organic (alkenes, alkynes, alkyls) as well as "organic-like" ligands are found in organo-metallic chemistry like phosphines, hydride, and CO.

Example: (C₅H₅) Fe (CO) ₂CH₃

 3) Bioinorganic Chemistry: Ligands which are provided by nature, especially including the side chains of amino acids, and many cofactors such as porphyrins.

Example: hemoglobin.

Many natural ligands are Werner complexes especially including water.

4) Cluster Chemistry: Ligands which also include other metals as ligands.

Example Ru3(CO)12

Older classifications of isomerism

In the older literature, one encounters:

1) Ionisation isomerism states that the possible isomers arise from the exchange between the outer sphere and inner sphere. In this classification, the "outer sphere ligands," may combine with the "inner sphere ligands" to produce an isomer.

 2) Solvation isomerism occurs when an inner sphere ligand is replaced by a solvent molecule. This classification is absolute because it considers solvents as being distinct from other ligands.

What are chemical indicators

Introduction 
Substance which undergo some easily detectable change (such as change of colour, precipitation, etc.) during titration and which thereby indicate the equivalence point are called Chemical indicators.

Example:  Phenolphthalein, Methyl orange, Methyl red, Starch, etc.

Main Characteristics Of Chemical Indicators

Chemical indicators possess one color in the presence of an excess of the substance to be estimated, and another in the presence of an excess of the standard solution of the reagent used and thus these substances indicate the exact end-point.  A familiar example of an indicator is litmus, which is blue in the presence of an excess of alkali and red in the presence of excess of acid.
A good chemical indicator must possess the following two essential characteristics.

1. The color change of the indicator must be clear and sharp, i.e. it must be sensitive.  Thus, it would be useless if 2 or 3 c.c. of the reagent is sufficient to bring out the color change.
2. The Ph-range over which the color change takes place must be such as to indicate when the reaction is complete.

Classification Of Chemical Indicators

All well-known indicators can be classified in two ways; either on the environment in which they are used or on the basis of the types of titrations in which they are used.  In general, an indicator may be internal or external.

1. Internal indicator: If the indicator is added to the liquid which is being titrated, it is called an Internal indicator viz. litmus solution, Phenolphthalein, potassium chromate, etc.
2. External indicator: If the indicator is used outside the vessel in which the reaction is taking place, and drops of the liquid are taken out of the reaction vessel from time to time and mixed with the indicator, it is called external indicator.

Potassium ferricyanide, the most familiar example of external indicator, is used during the titration of ferrous ions as it gives blue color with ferrous ions and a brown coloration with ferric ions and thus tells us when a ferrous solution has been completely oxidized to the ferric state.  The indicator is used as external since if it is added to the ferrous solution to start with, it would have been reacted with it.

Explosive chemical reactions

Introduction :
Chemical reactions that releases energy are known as exothermic reactions.

Case I: When the reaction proceeds slowly, released energy will be dissipated smoothly and there will be few noticeable effects other than an increase in temperature.

Case II: On the other hand, when the reaction proceeds very rapidly, the energy will not be dissipated smoothly. A huge amount of energy can be deposited into a relatively small volume of atmosphere, then manifest itself by a rapid expansion of hot gases, which in turn can create a shock wave or propel fragments outwards at high speed.
There are three primary fields of application for these chemcial explosions: propellants, explosives and pyrotechnics.

Propellants works when they create a high gas pressure for moving projectiles or rockets and for similar uses.

Explosives works when they create a disruption of solid or liquid bodies, as in construction, mining or warfare.

Pyrotechnics works when they have effects that are mainly sound and light, but include many other varied applications, mainly on a small scale.

Fireworks are used as an application for entertainment, a show of light, noise and motion.

Some more examples:

Black Powder: Black powder was invented as a pyrotechnic substance, then it was applied as a propellant in firearms, and finally used in engineering and mining. The history of black powder and firearms relates to Cannon.

Smokeless Powder: Vielle discovered how to make a propellant from cellulose nitrate in 1886. The work was started with low-nitrogen guncotton, or pyrocotton, with 11%-12% of nitrogen, and plasticized it with ether and alcohol. Pyrocotton will dissolve completely in this solvent. This gel was rolled out into sheets and then the sheets were broken up into powder, after this the powder formed into grains, and these grains, mixed with various additives to control the rate of burning, chemical properties and stability in storage, made a propellant called smokeless powder that could replace gunpowder, and was more powerful.

Aromatic Explosives: One of the first aromatic explosives was picric acid, or trinitrophenol, C6H2(NO2)3OH. This particular explosive was first prepared in 1771 by Woulfe as a dye, and was also used in medicine, long before it was first employed as an explosive in 1830. Name was so given because of it's extremely sharp or bitter taste, and also in Greek word it means pikros, "sharp." It forms pale yellow crystals of density 1.76 g/cc, melting at 122°C and exploding above 300°C. It is too sensitive to heat to be poured into shells, and must be press-loaded, meanwhile another effect of it is corrosion of metals, forming sensitive picrates. The most famous aromatic explosive is trinitrotoluene, called TNT for short. TNT is deficient in oxygen, so makes a cloud of black smoke. It is a popular bursting charge for shells and bombs, replacing picric acid after World War I.

Atomic number 81

 Introduction :

• Atomic number 81 belong to P-block elements.
• Atomic number 81 is Thallium and chemical symbol is ‘Tl’ from periodic table.
• Thallium belongs to Group13 and period 6.
• General electronic configuration of p-block element is [Rare gas] nS² np^{1 to 6}
• Thallium has atomic number 81 and mass number 204.383 The data is obtained from the periodic table.
• Atomic number 81 was found in iron pyrites, crookesite, hutchinsonite, and lorandite.  It is obtained in the by-product of zinc and lead smelting.
• Electronic configuration of Thallium:
• 1S², 2S², 2P⁶, 3S², 3P⁶, 3d¹⁰, 4S², 4P⁶, 4d¹⁰, 4f¹⁴, 5s², 5p⁶, 5d¹⁰, 6S², 6P¹
• Electron per energy level: 2, 8, 18, 32, 18,3
• Number of Electrons (with no charge): 81
• Number of Neutrons (most common/stable nuclide): 123
• Number of Protons: 81
• Oxidation States: 3,1
• Crystal Structure of Atomic number 81 is Hexagonal.
• Density (293 K) of thallium is 11.85 g/cm³.
• In Greek thallos mean green twig, representation for bright green line in its spectrum.
• Thallium is a Soft gray metal that looks like lead.
• Sir William Crookes discovered Thallium in the year 1861 in England.
• Thallium belongs to metal group.

Thallium is very soft and malleable and at room temperature, it can be cut with a knife.  Thallium has a metallic luster, but by exposing to air, it quickly diminishes with a bluish-gray tinge that resembles lead. It is preserved by keeping it under oil.

Image of Thallium metal: Appearance of thallium metal is silvery white colour.
                                            


Properties of Atomic number 81

• Atomic radius and ionic radius of Group 13 elements: Atomic radius and ionic radius increases down the group from boron to thallium

Elements	Boron	Aluminum	Gallium	Indium	Thallium
Atomic radius (pm)	85	121	135	155	190
Ionic radius (pm)	41	53.5	76	94	102.5

• Ionization potential of Thallium:

      First Ionization potential: 6.1083 eV.
      Second Ionization potential: 20.428 eV.
      Third Ionization potential: 29.829 eV.

• Oxidation states of Atomic number 81: Group 13 elements exhibit oxidation state of +3.  Thallium exhibit oxidation state of +1 and +3.  It is exhibited when ns², np¹ electrons are involved in bonding.

                   Tl       : [Xe] 4f¹⁴, 5d¹⁰, 6s², 6p¹
                            Tl¹⁺     : [Xe] 4f¹⁴, 5d¹⁰, 6s², 6p⁰
                   Tl³⁺     :  [Xe] 4f¹⁴, 5d¹⁰, 6s⁰, 6p⁰

• Inert pair effect of Thallium: In Inert pair effect, the outermost s electrons to remain no ionized or unshared in compounds of post-transition metals (or p-block elements). The term inert pair effect is frequently used in relation to the increasing stability of oxidation states that are 2 less than the group valence for the elements of groups 13, 14, 15 and 16. The term "inert pair" was first proposed by Nevil Sidgwick proposed the term "inert pair" in 1927. As an example in group 13 the Tl has+1 oxidation state and it is the most stable one and Tl^III compounds are comparatively less. The stability of Group 13 elements is given in the order,

                                        Al^I < Ga^I < In^I < Tl^I.

• Melting point (M.P.) and boiling points (B.P.) of Group 13 elements: Melting point depends on the size of the atom.  Smaller the atomic size, higher is the meting point. Boiling point decreases from boron to thallium. 

Elements	Boron	Aluminum	Gallium	Indium	Thallium
M.P.  (0C)	4275	2740	2475	2350	1745
B.P.  (0C)	2300	933.25	302.9	429.75	577

• Isotopes of Thallium:  There are 25 isotopes in thallium.  Atomic masses ranges from 184 to 210. Stable isotopes are only ²⁰³Tl and ²⁰⁵Tl .  ²⁰⁴Tl is the most stable radioisotope which is having a half-life of 3.78 years.

Uses of Thallium

• Thallium sulphate is odorless and tasteless and was once widely used as rat poison and ant killer. Since 1972 it is prohibited.
• To treat ringworm, other skin infections and to reduce the night sweating of tuberculosis patients, thallium salts were used. However it is limited due to their narrow therapeutic index.

Chemical reaction of Thallium

• Chemical reaction of thallium with air: When thallium metal is heated to red hot in the presence of air, thallium (1) oxide which is poisonous is formed.

                 2Tl _(s) + O_{2 (g)} → Tl₂O _(s)

• Chemical reaction of thallium with water: When Thallium metal is exposed to moist air, it tarnishes slowly and then it dissolves in water to form thallium (1) hydroxide which is poisonous is formed.

                2Tl _(s) + 2H₂O _(l) → 2Tl (OH) _(aq) + H_{2 (g)} ↑

• Chemical reaction of thallium with halogens: Thallium metal reacts rapidly with halogen to form dihalides.  Thallium (111) fluoride, thallium (111) chloride and thallium (111) bromide are formed.  All these are poisonous.

                                        2Tl(s) + 3F₂ (g) → 2TlF₃(s)
                                        2Tl(s) + 3Cl₂ (g) → 2TlCl₃(s)
                                        2Tl(s) + 3Br₂ (l) → 2TlBr₃(s)

• Reaction of thallium with acids: Thallium reacts with sulphuric acid and hydrochloric acid slowly

Calculating percent yield

The predicted yield is determined by the masses used in a reaction and the mole ratios in the balanced equation. This predicted yield is the "ideal". It is not always possible to get this amount of product. Reactions are not always simple. There often are competing reactions. 

 For example, if you burn carbon in air you can get carbon dioxide and carbon monoxide formed. The two reactions occur simultaneously. Some carbon atoms end up in CO and others end up in CO2. The typical calculation in a starting class assumes that there is only one path for the reactants. This is an over simplification.You know for example from real life that food is not always converted to energy. If you eat a cookie, some of it could end up stored as "fat" Ugh!

Chemists, like all other people, aren't perfect. When a chemist does a synthesis, she will end up creating less product than expected because of spills, incomplete reactions, incomplete separations, or a dozen other reasons. The percent yield is a way of measuring how successful a reaction has been.

To compute the percent yield, figure out how much product you should have made by using basic stoichiometry. (Note: this may involve a limiting reagent problem.) Then simply divide the amount of stuff you did form by the expected amount and multiply by 100%. If you get a number > 100%, you've made a serious error someplace.

Obviously, you want a high percent yield: if you have a ten step synthesis where the product from one reaction ends up as the reactants for the next and each synthesis has 90% yield, you'll end up with only ~35% yield for the overall reaction.

Example: You burn 10.0 grams of methane in an excess of oxygen and form 19.8 grams of water. What was your percent yield?

Solution : First, you need to find out how much product you would expect to make using basic stoichiometry. The reaction of methane with oxygen is shown below

CH4(g) + 2O2(g) -> CO2(g) + 2H2O(g)

You start with 10.0 grams of methane, which has a molecular weight of 16.04 g/mole, so you have 10.0 g/16.04 g/mole = 0.623 moles of methane.

The ratio between methane and water is 2 water for every 1 methane, so you expect to form

0.623 moles CH4 * 2 moles H2O/1 mole CH4 1.25 moles H2O

Now convert back to grams: the mole weight of water is 18.02 g/mole, so you should form

1.25 moles H2O * 18.02 g/mole = 22.5 g water

If the reaction had gone perfectly. You only formed 19.8 however, so your percent yield is

% yield = mass created/mass expected * 100%

% yield = 19.8 g/22.5 g = 88.0%

Standard gas volume

Introduction :
Each gas is characterized by the property of volume.  Volume is a space occupied by a gas. Volume is dependent on the temperature.  More the temperature more would be the volume.  Standard gas volume is defined as volume occupied by a gas at standard temperature and pressure.

 What are the figures for standard pressure and temperature?  The figures of standard pressure and temperature are adopted at 1 atmosphere and 273 degree Kelvin.  For the gas loss, the value of the units of pressure and temperature are always taken as atmosphere and degree kelvin.  The volume occupied by a gas at these standard conditions is called as standard volume.

Equations to find standard gas volume

Boyle established the relationship between pressure and the volume.Charles established the relation between pressure and temperature.
From both of these equations the universal gas law equation was derived and from the same ideal gas law equation was derived.
The ideal gas law equation is PV =nRT, here 'P' is pressure, 'V' is volume, 'n' is number of moles, 'R' is the gas constant and 'T' is temperature.  If the values for standard pressure and temperature are substituted at 1 atmosphere and 273 degree kelvin, the volume occupied by 1 mole of a gas comes to 22.4 liters.
Thus 22.4 liters is a standard volume of 1 mole of any gas.  This equation was derived by Avogadro. He quantified the volume occupied by 1 mole of gas at standard conditions

Illustration to show standard gas volume

The standard volume has been useful to find many other things in practical chemistry.Let us consider following problems.

Problem 1:
                   Find volume occupied by 64 grams of oxygen at STP
                                                       Or
                       Find the standard volume of 64 gms of oxygen.

Answer:  64 no. of moles of oxygen is = 64 / 32 = 2.
               If 1 mole occupies 22.4 litres, 2 moles would occupy 44.8 liters.

Problem 2:
                   Find the moles of the gas if the standard volume is 100 liters.

Answer: 1 mole occupies 22.4 liters,
             so 100 liters is occupied by 100 / 22.4 = 4.464 moles.

Percent volume concentration

Introduction :
Concentration of a solution depends upon the amount of solute present in the solution.  The concentration of the solution is expressed in many ways.  One of the important way of expressing the concentration is percent volume concentration.  Other means of expressing the concentration are mass percent which is nothing but the mass of the solute present in the solution expressed as percentage that is (mass of the solute/mass of solution) x 100.  Another way of expressing the concentration is by molarity it is the mole of solute present in a liter of the solvent it is expressed as mol/litre.  Yet another way of expressing the concentration is by molefraction is the fraction of moles that is present in the whole of the solution.  That is if two component A and B are present in the solution.  the mole fraction of A is the number of moles of A/moles of A + moles of B.

Concentration as volume percent:

In most of the liquid samples the concentration is expressed by volume percent
volume present = (volume of the solute/volume of the solution) x 100.  This is the easiest method of expressing the concentration of a liquid solution.
For example if you have 10%volume/volume of antifreeze that is ethylene glylcol in water it means that there is 10mL of ethylene glycol in 100mL of the soluiton or 10L of ethylene glycol in 100L of the solution

Problems on percent volume concentration:

Find out the volume percentage of ethanol when 10mL of ethanol is mixed in 190mL of the water?
Soluiton:

Volume of the solute that is ethanol is 10mL

volume of the solvent that is water is 190mL

total volume of the solution = volume of the solute + volume of the solvent = 10mL + 190Ml= 200mL
So volume percentage =(volume of solute  / volume of solution) x 100
= (10 / 200) x 100 = 5% v/V

Iupac nomenclature for organic compounds

IUPAC Rules for Nomenclature:

(i).Root words:

C1 -Meth, C2 -Eth, C3-Prop ,C4-Buta, C5- Penta, C6- Hexa, C7- Hepta,C8- Octa,C9-Nona,C10-Deca

(ii).Primary suffix:

                               Alkane   - C-C-       -ane
                               Alkene     -C=C-       -ene
                             alkyne       -C=_C-      -yne
1.Longest sum rule:
the longest continuous chain of carbon atoms is considered for naming the carbon compound, the prefix in the name of the compound depends on the number of carbons present in the compound.

2.Least Sum Rule:
In numbering the carbon atoms in the parent chain start at the end which  results in the use of lowest number for the substituent carbon atoms.

3.When identical substituent are present on the same carbon atom,the position of the substituent is repeated

4.if the carbon chain contain 2 or more than 2 identical substituent,then di- tri- tetra- words are used to indicate the number of substituents.

5.If the number of different groups are attached to the parent the chain ,then the naming is done in two ways:
(i). according to the IUPAC rules
(ii) the name is given to the compound following the increase in order of complexity of the group

6.when a carbon compound  has carbon chain having the same no.of carbon atoms,they having more number of branches is selected as the parent chain

7 If a carbon chain contains substituents which are at equal distance either from left are right side counting is done in such a way that the least number is given to substituens

8 When the main carbon chain in a carbon compound carries a branch which again contains a substituent,the position of the substituent in the branch is written in the brackets.

IUPAC Rules for naming Poly functional compounds:

A molecule can contain more than one functional group called as polyfunctional group,the functional group which specifies its class is called the principle functionl group the other functional groups are refered to as ' substituents'

Nomenclature Priority for determining the principle functional group.Highest priority at the top.
suffixes for functional groups:
Caboxylic acid     -COOH   (  -oic acid )
sulphonic acid    -SO3H  (sulphonic acid)
Ester                     - COOR ( -alkyl -  oate)
Acid halide           -COX  ( -oyl chloride)
amide                  -CO NH2 ( -amide)
nitrile                  -CN (-nitrile)
aldehyde         -CHO  (-al)
ketone             -CO-   (-one)
alcohol          -OH ( -ol)
amine             - NH2  (-amine)
ethers            -O-  (ether)
alkene          -C=C- (ene)
alkyne         -C=_C-   (-yne)


1.Identify principal functional group.this gives class name of  the structure.

2. Number the longest chain containing the principal functional group from the end closer to it.

3.Write the parent name corresponding to the no.of cabons in the longest chain.

4 Arrange the substituents names with position numbers in alphabetical order.

5.Prefix substituent name with the parent name.

6.The following functional groups are always named as substituents ,their names prefixed with the parent name.
ex:Cl - chloro; Br - bromo ;I -iodo ;F-flouro ;CN - cyano ; R - alkyl, OR - alkoxy ; NH2 -amine;NO2 -nitro  etc..

IUPAC Nomenclature rules with example:

7.Identify double/triple bonds. Number them with the number of the carbon atom at the head of the bond (i.e the carbon atom with the lesser number that it is attached to). For example a double bond between carbon atoms 3 and 4 is numbered as 3-ene. Multiple bonds of one type (double/triple) are named with a prefix (di-, tri-, etc.). If both types of bonds exist, then use "ene" before "yne" e.g. "6 13 diene 19 yne". If all bonds are single, use "ane" without any numbers or prefixes.

8. Arrange everything like in  this way: Group of side chains and secondary functional groups with numbers made in step 3 + prefix of parent hydrocarbon chain (eth, meth) + double/triple bonds with numbers (or "ane") + primary functional group suffix with numbers.
      Wherever it says "with numbers", it is understood that between the word and the numbers, you use the prefix(di-, tri-)

   9. Add punctuation:
         1. Put commas between numbers (2 5 5 becomes 2,5,5)
         2. Put a hyphen between a number and a letter (2 5 5 trimethylhexane becomes 2,5,5-trimethylhexane)
         3. Successive words are merged into one wordform (trimethyl hexane becomes trimethylhexane)
            NOTE: IUPAC uses one-word names throughout. This is why all parts are connected.

Ex:  CH3-CH(OH)-CH2-CH(CH3)-COOH

         5       4             3         2               1

From priority order -COOH  have higher rank ,therefore -COOH is the principal functional group.the structure is named as a carboxylic acid.
Longest chain : 5 carbons
so,parent name = pentanoic acid
Order of substituent 4-hydroxy -2-methyl
therefore,Name of the compound : 4-Hydroxy-2-methyl pentanoic acid.