Chemical compounds

Introduction:
We are going to see about the important chemical compounds.  A chemical compound is one of the pure chemical substance composed of molecules and formed combination of more than one different chemically bonded chemical elements.  Elements are more stable when the compounds are combined to form together.  Some important chemical compound names are organic compound, inorganic compound, biomolecules, organometallic compounds and so on.

Organic compound- Important chemical compound

Some important chemical compounds are
Acetaldehyde:  It is an organic chemical compound and also occurs in coffee.  The general formula is CH₃CHO.
Benzene:  Benzene is also an organic chemical compound and it is flammable liquid.  General formula is C₆H₆.
Butene:  Butylene or butene is an chemical compound.  It is colorless gas.  General formula is C₄H₈.
Ethene:  Ethylene or ethene is one of the chemical compound.  It is flammable gas and colourless.  The general formula of ethene is C₂H₄.
Formic acid:  Methanoic acid or formic acid is the carboxylic acid.  The general formula of formic acid is HCOOH.

Inorganic compound- Important chemical compound

Some important chemical compounds are
Aluminium chloride:  Aluminium chloride (AlCl₃) is the combination of aluminium and chlorine.
Ammonia:  Ammonia (NH₃)is the chemical compound.  It is colourless gas and pungent odour.
Calcium chloride:  It is one of the important chemical compound.  CaCl₂ is the combination of calcium and chlorine compounds.
Chromic acid:  Collection of compounds. It is a powerful oxidized agent.
Gallium phosphate:  GaPO₄ or (gallium orthophosphate) is a colourless crystal.
Hydrogen chloride:  HCl  combination of hydrogen and chlorine atom and soluble in water.
Magnesium oxide:  MgO is a moisture absorbent.  It used as raw material for making cement.
Nitrogen monoxide:  It is a chemical compound with chemical formula NO.
Biomolecules:

Some important chemical compounds are
Acetic acid:  The general formula is CH₃COOH.  It is pungent smell and sour taste.
Cellulose:  The general formula is C₆H₁₀O₅.  It is one of the organic compound.

Air chemical equation

Introduction :

Air is usually made up of a mixture of so many gases. Air comprises slightly over 20% of oxygen (O₂) and in relation to 78% nitrogen (N₂). Air also contains surplus quantities of Carbon Dioxide (about 0.03%) and even smaller quantities of other inert gases like Helium, Neon, Argon, etc. It has some low level Ozone O₃. Air usually exists as a mixture of all these gases it does exist in the compound form. It also contains small and varying quantity of water vapor. Which we are looking as clouds in the sky.The air chemical equation are give in Table 1

Air chemical equation:Chief constituent of gases

The chief constituent of air is nitrogen gas followed by oxygen

The first two gases nitrogen and oxygen make up 99.0% of the atmosphere by volume.

Nitrogen is moderately inert because of its strong triple bond holding the atoms jointly in the molecule. Whereas, the oxygen gas is synthesized by photosynthesis and removed by combustion and respiration.

Types of Air chemical equation:

The types of air chemical equation as follows

Reaction with Acetaldehyde: Oxygen gas is used in the preparation of acetaldehyde (ethanol) involves the following steps.

2CH₃CH₂OH + O₂ →2CH₃CHO + 2H₂O

Further oxidation of ethanoic acid with give rise to acetic acid which on further oxidation with carbon dioxide and water takes place on burning.

2CH₃CHO + O₂ → 2CH₃COOH

Reaction with Aluminum: Secondly oxygen reacts with aluminum metal

Aluminum metal undergoes a combination reaction with O₂ (g).

4Al + 3O₂ →2Al₂O₃

Reaction with Copper hydroxide: Copper (II) hydroxide degraded into copper (II) oxide and water when heated.

Cu (OH) ₂ → CuO + H₂O

Reaction with Heptanes: Heptanes, burns in air to give carbon dioxide

C₇H₁₆ + 11O₂ → 7CO₂ + 8H₂OH

Reaction with methyl ter butyl ether: The gasoline additive MTBE (methyl tert-butyl ether), C₅H₁₂O₂ (l), burns in air.

C₅H₁₂O₂ + 7O₂ →5CO₂ + 6H₂O

Physical properties of Air chemical equation:

• Oxygen exhibits its Compressibility that is isothermal properties with the chemical compounds.
• Oxygen shows high conductivity towards air, water, and other fluids.
• It has high density gradient against air, water and other fluids, various solids and other common liquids.
• It is relatively rough to handle because of its high tensile strength.

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Types of chemical reactions

Introduction :
Chemical reaction is defined as the changing one set chemical reactions into other set of chemical reactions. There is no need to give input to the chemical reactions. Chemical reactions involves the transfer of electrons and the formation of chemical bonds. Reactants are the substance which are involved in the chemical reactions. Nuclear reactions are also takes place in the chemical reactions. There are three types of chemical reactions are present.

Different Types of Chemical Reactions:

There are three types of chemical reactions are present. The three types are defined in the following,
Oxidation reaction and reduction reaction:
Oxidation and reduction reaction are defined as one substance gets oxidised and the other substance gets reduced. Simply it is defined as the loss or gain of electrons. Some of the examples involves in this type of chemical reaction are,
1. Iron and oxygen reaction:
In this example, the ion reacts with the oxygen and it produces oxide. In this the oxidised substance is iron. The chemical reaction is as follows,
4Fe + 3O₂ `->`  2Fe₂O₃
Where
            Fe = iron
            O₂ = oxygen
            2Fe₂O₃  = oxide
2. Ethanol and oxygen reaction:
In this example, the ethanol reacts with the oxygen, thus producing an acid called ethanol. In this the oxidised substance is ethanol.
CH₃ CH₂ OH + [ O ]    `->` CH₃COOH
Where,

CH₃ CH₂ OH = ethanol

[ O ] = other chemicals

CH₃COOH = ethanoic acid

Acid – Metal oxide Reaction:
The formation of salt and water by using the reaction of acid and the metal oxide is called as the acid – metal reaction. The example of chemical reaction is, The acid hydrochloric acid reacts with the metal oxide iron oxide,thus producing  iron chloride and solvent water
3HCl + Fe₂O₃ `->` FeCl₃ + 3H₂O

HCl = hydrochloric acid

Fe₂O₃ = iron oxide

FeCl₃ = iron chloride

H₂O = water

Three types of chemical reaction

Acid – Base Reactions:
The formation of salt and water by using the reaction of acid and base are called as the Acid-Base reactions. The examples for this chemical reaction are ,
The acid hydrochloric acid reacts with the base sodium hydroxide, thus producing a salt called sodium chloride and solvent water
HCl + NaOH NaCl + H₂O
Where,
HCl = hydrochloric acid
NaOH = sodium hydroxide
NaCl = sodium chloride
H₂O = water

Another example,
The acid sulphuric acid reacts with the base potassium hydroxide, thus producing a potassium sulphate and the solvent water
H₂SO₄ + 2KOH K₂SO₄ + 2H₂O
Where,
H₂SO₄ = sulphuric acid
KOH = potassium hydroxide
K₂SO₄ = potassium sulphate
H₂O = water

Ionization energy periodic table

Ionization energy is the electrostatic attraction that changes the trend in the groups and periods of a periodic table

Introduction to Ionization energy periodic table

Ionization energy is the minimum amount of energy required to remove an electron from the outermost orbit of an atom to the minimum distance from the atom so that no electrostatic interaction exists between the separated electron and the cation so formed.

explanation for Ionization energy from periodic table

Electrons present in an atom are attracted towards the nucleus due to the positive charge of protons. Therefore, some energy is required to remove an electron from an atom. This energy is referred to as the "Ionization Energy", as when the electron is removed from an atom, the atom is converted to a positively charged ion.
THe energy required to remove the first electron from a neutral atom is called the First Ionization energy, the energy required to remove the second electron from a positive cation is called the Second Ionization Energy, and so on.

Factors on which the ionization energy of an atom depends(periodic table)

1. Atomic size:- The greater the atomic size, the greater is the distance of the outermost shell from the protons inside the nucleus. Thus, there is lesser pull of the protons on the electrons of the last shell. Thus, the greater the atomic size, the lesser is the ionization energy of that element.
2. Nuclear charge:- Greater nuclear charge means greater attraction of the elecrons by the protons inside the nucleus. Thus, if the nuclear charge is greater, it becomes difficult to remove electrons from the outermost shell. Thus, the greater the nuclear charge, the greater is the Ionization Energy.

Varation of ionization energy in the Periodic table:-

1. Across a Period:- 
   Ionization energy of elements increases as one moves from left to right in a row of the Periodic Table.
   Reason:-As we move from left to right in a row of the Periodic Table, the number of rows in the atoms of successive elements remains the same whereas the nuclear charge increases. This causes the electrons to be attracted more strongly towards the nucleus, and hence, the ionization energy increases.
2. In a Group:-
   As one moves down a group in the Periodic Table, the ionization energy of successive elements decreases.
   Reason:-As we move down a group, the number of shells in the atoms of elements increases and the atomic number also increases. This causes an increase in the atomic size as well as in the nuclear charge. But the increase in atomic size overcomes the increase in nuclear charge, and thus it becomes more easier to remove electrons from atoms of elements as one moves down a group.

Atomic size

Introduction
 Let us discuss about the atomic size. According to modern the Atomic Theory, an atom is the minimum particle of an element which takes part in chemical reactions it maintains its identity all the way through every physical changes and chemical changes. Atoms of elements are quite reactive. They, therefore, normally do not exist in the free state except the atoms of noble or rare gases. Next we see the size of an atomic.

Atomic size

It has been found that the atoms of all elements are made up from three basic particles and that the atoms of different elements contain different numbers of these three particles. The particles are electron, proton and neutron. Since an atom has in general no charge, the many electrons external the nucleus is similar to the number of protons inside the nucleus. The even with microscope, they do not perceive them atoms are small.
               The atoms are generally declaring the building blocks of matter. They are very very small and do not be seen even by the majority of powerful microscope. An idea of the extremely small size of the atom can be had from the fact that 1cm of space can accommodate about 35,000,000 atoms arranged end to end in a line. The atomic radius is called as size of the atom is indicated by its radius. The atomic radius of the smallest atom, hydrogen is 0.37 x 10^-10 m or 0.037 nm. The nm is normally declaring the nanometer.
              The 1nm is normally declare the 1nm=10^-9 m or 10⁹ nm = 1 m. The small dimensions of hydrogen atom or atoms in general can be seen as compared with the size of some common objects given in the following table.

Relative sizes of some common objects

Relative sizes
Radii	Examples
10-1 m 10-2 m 10-4 m 10-8 m 10-9 m 10-10 m	Watermelon Ant Grain of sand A molecule of haemoglobin A molecule of water An atom of hydrogen

Mole Chemistry

You must hear about mole concept in chemistry that is basis of stoichiometry. Let’s first discuss what is a Mole in Chemistry? The amount of pure substance having the same number of atoms as in 12 grams of carbon-12 is known as one mole. In Chemistry Mole  is equals to 6.023 X 1023 or Avogadro number.

Now first question comes to your mind that what is a Mole? Mole definition states that the number of atoms in exactly 12 g of 12C is known as one mole. All stoichiometry is essentially based on the Mole Chemistry.

Amedeo Avogadro performed an experiment in 1811 and concluded that at the same temperature and pressure, equal volumes of gases contain equal numbers of molecules.

Hypothetically he purposed that number known as Avogadro number; 6.02 X 1023 or 602 000 000 000 000 000 000 000. Hence one mol of anything has 6.02 x 1023 particles such as one mole of silver contains 6.02 x 1023 atoms of silver.

Let’s take a simple example of calculation of mols present in compound such as water. A of mol of water contains 6.02 x 1023 molcules weighs 18 gm. Hence a mol is a collection of atoms with a mass equal to the atomic weight in grams.

Mole of an element is directly related to atomic weight or atomic mass formula of that element. For example; the atomic weigh of lithium is 6.941amu, it means 6.941 grams of lithium contains 6.02 x 1023 atoms of lithium.

The mole concept can be used for the relation between the number of particles and the mass of a substance. Let’s do an example for that. Calculate the number of atoms present in 0.24 mol of sodium. As we known, in one mole of sodium there are 6.02 × 1023 atoms. Therefore in 0.24 mols of sodium contain 0.24 x 6.02 × 1023 = 7.22 x 1022 atoms of sodium.
The best way to express the atomic mass of any substance in grams is known as molar mass. The only change is in their units. Such as the atomic mass of iron is 55.85 amu and molar mass is 55.85 g/mole. For diatomic molecules the molar mass units is just double to its atomic mass. Like the molar mass of oxygen is 32.00 g/mol and atomic mass is 16.00 amu. The molar mass of polyatomic compounds is the sum of molar mass of each atom. Let’s calculate the molar mass of magnesium nitrate, Mg(NO3)2 is sum of atomic mass of Mg, 2N and 6O.
Molar mass of Mg(NO3)2 = 24.31 + 2(14.01 + 16.00 + 16.00 + 16.00)
=24.31 + 2(62.01) = 148.33
The relation between molar mass, mol and number of particle can be written as;
6.02 × 1023 particles = one mol = molar mass

Laws of Thermodynamics

Keywords

The Second Law of Thermodynamics

The Zeroth Law of Thermodynamics

Second Law Thermodynamics

Second Law of Thermodynamics Examples

There were some phenomenon and concepts observed by scientist which cannot explain by using the zeroth law of thermodynamics and 1^st law. As necessity is the mother of discovery so it developed the second law of thermodynamics.

There are many formulations and applications of the 2^nd Law. To understand the law, batter to take some second law of thermodynamics problems like production of heat in a heater after passing the current (work) a wire (resistance).

Electricity (work) heat

Therefore as per first law of thermodynamics;

Q = W

But this law does say anything about the direction of the energy transfer. It means we can reverse the process to produces electricity by passing heat.

However, we know it’s not possible practically. So there must be some kind of directions followed by process.

Let’s take another example to understand Second Law Thermodynamics. Take a cold can of soda and placed in a warm room. According to 1^st law, heat will be transferred from surroundings to the soda. As system is in no motion, so work done will zero and Q will be positive as system is absorbing some energy.

But we cannot say anything for reverse process, transfer of energy to room and decreases the temperature of soda can. No doubt, from various experiments and everyday life, we know that heat can only transferred spontaneously from a warm system to cold one.

Now to understand the direction of various processes, there are two statements given by Clausius and Kelvin are as follows;

1. There is no such type of process, in which heat transferred from low temperature to high temperature.
2. In any thermodynamic process, the absorption of heat from a reservoir cannot convert completely into work.

There are generally two cycles studied for 2^nd law;

1. Heat engine: Converting heat to net work.
2. Refrigerator: transfer heat from low temperature to high temperature medium.

In both cycles; there is a thermal reservoir which can supply or absorb heat without changing temperature. The thermal reservoir with high temperature is called as source and with low temperature, known as sink. In a thermodynamic cycle, source can supply heat to the system and sink can absorb heat.

A heat engine receives heat from a high temperature source and a fraction of the heat converted into work. The remaining heat rejected to a low temperature sink.

According to 1^st law of thermodynamic; Q_NET = W_NET

While from 2^nd law; Q _out>0

Efficiency of heat engine can give by; η= W_net/Q_input

or η= Q_input –Q_output /Q_input

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