At equilibrium, the concentration of the reactants and products does not change. The addition of more reactants or products to the reacting system at equilibrium causes an increase in their respective concentration.
According to Le-Chatelier's principle, the effect of increase in concentration of a substance is to shift the equilibrium in a direction that consumes the added substance. For example,
H₂(g) + I₂(g) ≓ 2HI(g)
The addition of H₂ or I₂ to the equilibrium mixture, disturbs the equilibrium. In order to minimize the stress, the system shifts the reaction in a direction where H₂ and I₂ are consumed i.e., formation of additional HI would balance the effect of added reactant. Hence the equilibrium shifts to the right (forward direction). i.e., the equilibrium is re-established. Similarly, removal of HI (Product) also favours forward reaction.
If HI is added to the equilibrium mixture, the concentration of HI is increased and system proceeds in the reverse direction to nullify the effect of increase in concentration of HI.

A pure solid always has the same concentration at a given temperature, as it does not expand to fill its container i.e., it has the same no. of moles of its volume. Therefore the concentration of pure solid is a constant. So the expression if K_C and K_P, is K_C = [CO₂], K, = P_CO2

(i) Restricted rotation around C = N (oximes) gives rise to geometrical isomerism in oximes. Here syn and anti are used instead of cis and trans respectively.
(ii) In the syn isomer the H atom of a doubly bonded carbon and -OH group of doubly bonded nitrogen lie on the same side of the double bond, while in the anti isomer, they lie on the opposite side of the double bond.
(iii) for e.g.,

(i) \({ CH }_{ 3 }-{ CH }_{ 2 }-\underset { \overset { | }{ { CH }_{ 3 } } }{ CH } -{ CH }_{ 2 }-CHO\)
(ii)

(iii) \({ H }_{ 3 }C-{ CH }_{ 2 }-\overset { \underset { | }{ COOH } }{ CH } -{ CH }_{ 2 }-\overset { \underset { | }{ COOH } }{ CH } -{ CH }_{ 2 }-{ { CH }_{ 2 } }-{ CH }_{ 3 }\)

(i) The pure water moves through the semipermeable membrane to the NaCI solution due to osmosis.
(ii) This process can be reversed by applying pressure greater than the osmotic pressure to the solution side. Now the pure water moves from the solution side to the solvent side and this process is called reverse osmosis.
(iii) Reverse osmosis can be defined as a process in which a solvent passes through a semipermeable membrane in the opposite direction of osmosis, when subjected to a hydrostatic pressure greater than the osmotic pressure.

1. The error due to weighing the solute can be minimised by using concentrated stock solution that requires large quantities of solute.
2. We can prepare working standards of different concentrations by diluting the stock solution which is more efficient since consistency is maintained.
3. Some of the concentrated solutions are more stable and are less likely to support microbial growth than working standards used in the experiments.

Optical isomerism:
Compounds having same physical and chemical property but differ only in the rotation of plane of the polarized light are known as optical isomers and the phenomenon is known as optical isomerism.
Some organic compounds such as glucose have the ability to rotate the plane of the plane polarized light and they are said to be optically active compounds and this property of a compound is called optical activity. The optical isomer, which rotates the plane of
the plane polarised light to the right or in cloclauisl direction is said to be dextrorotary (dexter means right) denoted by the sign (+), whereas the compound which rotates to the left or anticloclanrise is said to be leavo rotatory (leanues mean left) denoted by sign(-).
Dextrorotatory compounds are represented as 'd' or by sign (+) and lavorotatory compounds are ( - ) represented as 'l' or by sign (-).
Enantiomerism and optical activity: An optically active substance may exist in two or more isomeric forms which have same physical and chemical properties but differ in terms of direction of rotation of plane polarized light, such optical isomers which rotate the plane of polarized light with equal angle but in opposite direction are known as enantiomers and the phenomenon is knovrrn as enantiomerism. Isomers which are non-super impossible mirror images of each other are called enantiomers.
conditions for enantiomerism or optical isomerism:
A carbon atom whose tetra vaiency is satisfied by four different substituents (atoms or groups) is called a symmetric carbon or chiral carbon. It is indicated by an asterisk as C*. A molecule Possessing chiral carbon atom and non-super impossible to its own mirror image is said to be a chiral molecule or asymmetric, and the pioperty is called chirality or dissymmetry.

i) Butan.- I - ol & Butan - 2 -ol are position isomers. - Position isomerism
ii) Butan -I -ol & 2-methyl propan - I - ol are chain isomers - Chainisomerism
iii) Butan -I - ol and I - methoxy propane are functional isomers - Functional isomerism
iv) 1 - methoxy Propane and ethoxy ethane and 2 - methoxy Propane are metamers - Metamerism

\({\Delta P\over P_A^o}={W_B\times M_A\over M_B\times W_A}\)
In a 2 % solution weight of the solute is 2g and solvent is 98g
ΔP = P_A - P_solution = 1.013 - 1.004 bar = 0.009 bar
\(M_B={P_A^o\times W_B\times M_A\over \Delta P\times W_A}\)
M_B = 2 x 18 x 1.013/(98 x 0.009)
= 41.3 g mol^-1.

If a system at equilibrium is disturbed, then the system shifts itself in a direction that nullifies the effect of that disturbance.

i) \(K_{p}=K_{c}(R T)^{\Delta n_{g}}\)
K_p = Equilibrium constant in term of partial Pressures.
K_c = Equilibrium constant in term of concentration.
R = Gas constant; T = Temperature
\(\Delta \mathrm{n}_{\mathrm{g}}\) = Difference between the sum of number of moles of products and the sum of number of moles of reactants in gas phases.
ii) Synthesis of HI:
\( \mathrm{H}_{2(\mathrm{~g})}+\mathrm{I}_{2(\mathrm{~g})} \rightleftharpoons 2 \mathrm{HI}_{(\mathrm{g})} \)
\(\Delta n_{g}=0 \therefore K_{p}=K_{c}(R T) \Delta n_{g}\)
\(K_{p}=K_{c}(R T)^{\circ} \)
\(K_{p}=K_{c} \text {. }\)

(i) A carbon atom whose tetravalency in satisfied by four different substituents (atoms (or) groups) is called asymmetric carbon (or) chiral carbon. The optical isomer should have one or more chiral carbon to show optical activity.
(ii) The molecule possessing chiral carbon atom and is non-superimposable its own mirror image is said to be chiral molecule and the property is called chirality or dissymmetry.

van't Hoff factor (i) is defined as the ratio of the actual molar mass to the abnormal molar mass of the solute.
\(i=\cfrac { Normal\ (actual)\ molar\ mass }{ Abnormal\ (observed)\ molar\ mass } \)
\(i=\cfrac { observed\ colligative\ property }{ Calculated\ colligative\ property } \)

\({ K }_{ c }=\cfrac { \left[ { NH }_{ 3 } \right] ^{ 2 } }{ \left[ { N }_{ 2 } \right] \left[ { H }_{ 2 } \right] ^{ 3 } } =\cfrac { 1.2\times { 10 }^{ -2 } }{ 1.5\times { 10 }^{ -2 }\times \left( 3\times { 10 }^{ -2 } \right) ^{ 3 } } \)

K_H is a empirical constant with the dimensions of pressure. The value of 'K_H' depends on the nature of the gaseous solute and solvent.

Osmosis, which is a spontaneous process by which the solvent molecules pass through a semi permeable membrane from a solution of lower concentration to a solution of higher concentration.

Consider that 'a' moles of PCl , is taken in container of volume 'V'
Let x moles of PCl₅ be dissociated into x moles of PCl₃ and x moles of Cl₂

Applying law of mass action
\(\\ \\ { K }_{ C }=\cfrac { \left[ { PCl }_{ 3 } \right] \left[ { Cl }_{ 2 } \right] }{ \left[ { PCl }_{ 5 } \right] } =\cfrac { \left( \frac { x }{ V } \right) \left( \frac { x }{ V } \right) }{ \frac { a-x }{ V } } =\cfrac { { x }^{ 2 } }{ \left( a-x \right) V } \) 
K_p, calculation: K_P= K_C . RT^Δng
Δn_g = 2-1 = 1
We know that = PV = nRT
\(RT=\cfrac { PV }{ n } \) 
Where 'n' is the total number of moles at equilibrium
n = a - x + x + x = a + x
\({ LK }_{ P }=\cfrac { { x }^{ 2 } }{ \left( a-x \right) V } .\cfrac { PV }{ n } \)
\({ K }_{ P }=\cfrac { { x }^{ 2 }\times PV }{ \left( a-x \right) V(a+x) } \)
\({ K }_{ P }=\cfrac { { x }^{ 2 }P }{ \left( a-x \right) \left( a+x \right) } \)

Let us consider the formation of HI in which, 'a' moles of hydrogen and 'b' moles of iodine gas are allowed to react in a container of volume V. Let 'x' moles of each of H₂ and I₂ react together to form 2x moles of HI.
H₂(g) + I₂(g) ⇌ 2HI(g)

Applying law of mass action
\({ K }_{ C }=\cfrac { \left[ HI \right] ^{ 2 } }{ \left[ { H }_{ 2 } \right] \left[ I_{ 2 } \right] } \) 
\({ K }_{ C }=\cfrac { \left( \cfrac { 2x }{ V } \right) ^{ 2 } }{ \cfrac { \left( a-x \right) }{ V } \cfrac { \left( b-x \right) }{ V } } =\cfrac { { 4x }^{ 2 } }{ \left( a-x \right) \left( b-x \right) } \)
The equilibrium constant K_p can also be calculated as follows:
We know the relationship between the K_c and K_p
K_P, = K_C . RT^Δng
Here the
Δn_g = n_p - n_r = 2 - 2 = 0
Hence, K_P = K_C
\(\\ \\ \\ { K }_{ P }=\cfrac { { 4x }^{ 2 } }{ \left( a-x \right) \left( b-x \right) } \) 

Dumas method:
Principle: This method is based on the fact that nitrogeneous compound when heated with cupric oxide in an atmosphere of CO₂ yields free nitrogen.
\({ C }_{ x }{ H }_{ y }N_{ 2 }+\left( 2x+\cfrac { 1 }{ 2 } \right) CuO\longrightarrow x{ CO }_{ 2 }+\cfrac { y }{ 2 } { H }_{ 2 }O+\cfrac { z }{ 2 } { N }_{ 2 }+\left( 2x+\cfrac { y }{ 2 } \right) cu\)
Traces of nitrogen are reduced to elemental nitrogen by passing over heated copper spiral.
Description of the apparatus:

CO₂ Generator: CO₂ needed in this process is prepared by heating magnetite or sodium bicarbonate contained in a hard glass tube (or) by the action of dil. HCl on marble in a kipps apparatus. The gas is passed through the combustion tube after dried by bubbling through cone. H₂SO₄.
Combustion tube: The combustion tube is heated in a furnace is charged with
(a) A roll of oxidised copper gauze to prevent the back diffusion of products of combustion and to heat the organic substance mixed with CuO by radiation
(b) a weighed amount of organic substance mixed with excess of CuO
(c) a layer of CuO packed in about 2/3 length of the tube and kept in position by loose asbestos plug on either side and
(d) a reduced copper spiral which reduces any oxides of nitrogen formed during combustion of nitrogen.
Schiff's nitromete: The nitrogen gas obtained by the decomposition of the substance in the combustion tube is mixed with considerable excess of CO₂. It is estimated by passing
nitro meter when CO₂ is absorbed by KOH and the nitrogen gas gets collected in the upper part of the graduated tube.
Calculation:
Weight of the substance taken = Wg
Volume of nitrogen = V ₁L
Room temperature = T ₁K
Atmospheric pressure = P mm Hg
Aqueous tension at room temperature = P mm of Hg
\(\therefore\) Pressure of dry nitrogen = P-P' = P₁mm Hg
P_o'V_o and Tobe the pressure, volume and temperature respectively of dry nitrogen at S.T.P.
Then,\(\cfrac { { P }_{ o }{ V }_{ o } }{ { T }_{ o } } =\cfrac { P_{ 1 }{ V }_{ 1 } }{ { T }_{ 1 } } \) 
\(\therefore { V }_{ o }=\cfrac { { P }_{ 1 }{ V }_{ 1 } }{ { T }_{ 1 } } \times \cfrac { { T }_{ o } }{ { P }_{ o } } \) 
\({ V }_{ o }=\cfrac { { P }_{ 1 }{ V }_{ 1 } }{ { T }_{ 1 } } \times \cfrac { 273K }{ 760mm\quad Hg } \) 
22.4 L of N₂ at STP weigh 28 g of N₂
\(\therefore\) VoL of N₂ at STP weigh \(\cfrac { 28 }{ 22.4 } \times { V }_{ O }\) 
W g of organic compound contain \(\cfrac { 28 }{ 22.4 } \times { V }_{ O }\ g\ of\ { N }_{ 2 }\)
\(\therefore\) 100 g of organic contain \(\cfrac { 28 }{ 22.4 } \times \cfrac { { V }_{ o } }{ w } \times 100=\%of\quad nitrogen\)  

I step: Preparation of sodium fusion extract: A small piece of Na dried by pressing between the folds of filter paper is taken in"a fusion tube and it is heated. When it melts to a shining globule, a pinch of organic compound is added to it. The tube is then heated till the reaction ceases and becomes red hot. Then the test tube is plunged in about 50 ml of distilled water taken in a china dish and break the bottom of the tube by striking against the dish. The contents of the dish is boiled for about 10 minutes and then filtered. This filtrate is known as lassaigne's extract (or) sodium fusion extract.
II step: Test for Nitrogen: If Nitrogen is present, it gets converted to sodium cyanide which reacts with freshly prepared ferrous sulphate and ferric ion followed by cone. HCI and gives a Prussian blue colour (or) green coloured precipitate. It confirms the presence of nitrogen. HCI is added to dissolve the greenish precipitate of ferrous hydroxide produced by the action of NaOH on FeSO₄ which would otherwise mark the Prussian blue precipitate. Reactions involved.
\(Na+C+N\longrightarrow NaCN\) 
\({ FeSO }_{ 4 }+2NaOH\longrightarrow Fe\left( OH \right) _{ 2 }+{ Na }_{ 2 }{ SO }_{ 4 }\) 
\(\underset { Sodiumferrocyanide }{ 6NaCN+Fe\left( OH \right) _{ 2 }\longrightarrow { Na }_{ 4 }\left[ Fe\left( CN \right) _{ 6 } \right] +2NaOH } \)
\(\underset { Ferric\quad ferro\quad cyanide\\ (Prussianblue) }{ 3{ Na }_{ 4 }\left[ Fe\left( CN \right) _{ 6 } \right] \longrightarrow { Fe }_{ 4 }\left[ Fe\left( CN \right) _{ 6 } \right] +12Nacl } \)
If both N & S are present, a blood red colour is obtained due to the following reactions.
\(Na+C+N+S\overset { \Delta }{ \longrightarrow } \underset { Sodium\quad sulphocyanide }{ NACNS } \) 
\(3NaCNS+FeCl_{ 3 }\longrightarrow Fe\left( CNS \right) _{ 3 }+3Nacl\)
\(3NaCNS+FeCl_{ 3 }\longrightarrow \underset { Ferric\quad sulphocyanide\\ (Blood\quad red\quad colour)\qquad }{ Fe\left( CNS \right) _{ 3 }+3Nacl } \)

Ideal solutions: The solutions which obey Raoult's law over the entire range of concentration are known as ideal solutions. Ideal solutions are formed by mixing the two components which are identical in molecular size, in structure and have almost identical intermolecular forces.
Examples:
(i) Benzene and toluene
(ii) n-Hexane and n-Heptane
(iii) Chlorobenzene and bromobenzene.
Characteristics:
(i) They must obey Raoult's law.
(ii) ΔH mixing should be zero.
(iii)ΔV mixing should be zero, i.e. volume change on mixing is zero.

Non-ideal solutions : The solutions which do not obey Raoult's law are called non-ideal solutions. In case of non-ideal solutions there is change in volume and heat energy when the two componnts are mixed.
Characterstics :
(i) They does not Rault's law.
(ii)△V = mix ≠ 0
(iii) △H mix ≠ 0
Behaviour of Ideal Solutions: A plot of P_I or P₂ versus the mole fraction x₁ and x2 for an ideal solution gives a linear plot. These Lines (I and II) pass through the points and respectively when x _I and x₂ is equal to unity. Similarly the plot (Line III) of P_total versus x₂ is also linear. The minimum value of P_total is P_total and the maximum value is P₂⁰, assuming that component I is less volatile than component 2, i.e. P1 O < P2 O

(i) The measurement of relative lowering of vapour pressure can be used to determine the molar mass of a non-volatile solute.
(ii) A known mass of the solute is dissolved in a known quantity of solvent. The relative lowering of vapour pressure is measured experimentally.
(iii) According to Raoult's law, the relative lowering of vapour pressure is
\(\cfrac { { P }_{ solvent }^{ o }-{ P }_{ solution } }{ { P }_{ solvent }^{ o } } =xB\)
W_A = weight of solvent, WB = weight of solute
M_A= Molar mass of solvent, MB = molar mass of solute
\(\therefore { x }_{ B }=\cfrac { { n }_{ B } }{ { n }_{ A }+{ n }_{ B } } \)
where n_A= number of moles of solvent, n_B = number of moles of solute.
For dilute solution, n_A>> nB, n_A + n_B≈nA.
Then ,\({ x }_{ B }=\cfrac { { n }_{ B } }{ { n }_{ A } } \)
Number of moles of solvent and solute are
\({ n }_{ A }=\cfrac { { W }_{ A } }{ { M }_{ A } } .{ n }_{ B }=\cfrac { { W }_{ B } }{ { M }_{ B } } \)
\(\therefore { x }_{ B }=\cfrac { \frac { { W }_{ b } }{ { M }_{ B } } }{ \frac { { W }_{ A } }{ { M }_{ A } } } \)
Thus, relative lowering of vapour pressure = \(\cfrac { \frac { { W }_{ B } }{ { M }_{ B } } }{ \frac { { W }_{ A } }{ { M }_{ A } } } \)
Relative lowering of vapour pressure = \(\cfrac { { P }^{ o }-P }{ { P }^{ o } } \) 
\(\cfrac { { P }^{ o }-P }{ { P }^{ o } } =\cfrac { { W }_{ B }-{ M }_{ A } }{ { W }_{ A }\times { M }_{ B } } \)
From the above equation, molar mass of the solute MB can be calculated using the known values of W_A'W_B' M_Aand the measured relative lowering of vapour pressure.

(i) Fisher projection formula:
This is a method of representing three dimensional structures in two dimension. In this method, the chiral atom(s) lies in the plane of paper. The horizontal substituents are pointing towards the observer and the vertical substituents are away from the observer. Fisher projection formula for tartaric acid is given below.


(ii) Sawhorse projection formula :
Here the bond between two carbon atoms is drawn diagonally and slightly elongated. The lower left hand carbon is considered lying towards the front and the upper right hand carbon towards the back. The Fischer projection inadequately portrays the spatial relationship between ligands attached to adjacent atoms. The sawhorse projection attempts to clarify the relative location of the groups.

(iii) Newman projection- formula:
In this method the molecules are viewed from the front along the carbon-carbon bond axis. The two carbon atom forming the bond is represented by two circles. One behind the other so that only the front carbon is seen. The front carbon atom is shown by a point where as the carbon lying further from the eye is represented by the origin of the circle. Therefore, the C-H bonds of the front carbon are depicted from the circle while C-H bonds of the back carbon are drawn from the circumference of the circle with an angle of 1200 to each other.

(i) They are covalent compounds of carbon and generally insoluble in water and readily soluble in organic solvent such as benzene, toluene, ether, chloroform, etc ...
(ii) Many of the organic compounds are inflammable  (except CCI₄).They possess low boiling and melting points due to their covalent nature.
(iii) Organic compounds are characterised by functional groups. A functional group is an atom or a specific combination of bonded atoms that react in a characteristic way, irrespective of the organic molecule in which it is present. In
almost all the cases, the reaction of an organic compound takes place at the functional group. They exhibit isomerism which is a unique phenomenon.
(iv) Homologous series: A series of organic compounds each containing a characteristic functional group and the successive members differ from each other in molecular formula by a CH₂ group is called homologous series.
Alkanes: Methane (CH₄) Ethane (C₂H₆)  Propane (C₃H₈) etc.

Homologous series: A series of organic compounds each containing a characteric functional group and the successive' members differ from each other in molecular formula by a CH₂ group is called homologous series. Eg.
Alkanes : Methane (CH₄), Ethane (C₂H₆), Propane (C₃Hg) etc .
Alcohols: Methanol (CH₃OH), Ethanol (C₂H₅OH) Propanol (C₃H₇OH) etc ..)
Compounds of the homologous series are represented by a general formula Alkanes CnH_2n+2' Alkenes C_nH_2n, Alkynes C_nH_2n-2 and can be prepared by general methods. They show regular gradation in physical properties but have almost similar chemical property.