Colligative Properties of Solutions

The Colligative Properties of Solutions are :-

1.     Relative Lowering of the Vapor Pressure

2.     Elevation in Boiling Point

3.     Depressions in Boiling Point

4.     Osmosis

When a nonvolatile solute is added to a volatile solvent then the vapor pressure decreases.

The vapor pressure of a solution depends on the concentration of the solution irrespective of its identity.

The vapor pressure of a solvent is less than that of the pure solvent.

The vapor pressure is directly proportional to the mole fraction of the solution.

p_{1 =} x₁ p₁^o

The reduction in the vapor pressure:-

Δp₁ = p₁^o – p₁

Δp₁ = p₁^o – x₁ p₁^o

Δp₁ = p₁^o (1 – x₁)

The left side of the equation is called relatively lowering of vapor pressure and is equal to the mole fraction of the solute.

Here n₁ and n₂ are the number of moles of the solvent and solute respectively present in the solution.

The vapor pressure of a liquid increases with the increase in the temperature.

A liquid boils at the temperature at which the vapor pressure is equal to the atmospheric temperature.

For example, Water boils at 100 ^oC because at 100 ^oC the vapor pressure of water is

1.013 Bar (1 atmosphere) equal to the atmospheric pressure.

Solid State Chemistry

Fourteen Bravais Lattice:-

• Cubic               Primitive, Body Centered Cubic, Face Centred Cubic
• Tetrahedral       Primitive, Body Centered
• Orthorhombic   Primitive, Body Centered, Face Centred, End Centered
• Hexagonal        Primitive 
• Rhombohedral  Primitive
• Monoclinic        Primitive,End Centered
• Triclinic             Primitive

Longest Bond Length

I

III

II










Among I, II, III which has the longest bond length? 


In [I] the number of hyperconjugable H atom is 10.
In [II] the number of hyperconjugable H atom is 6.
In [III] the number of hyperconjugable H atom is 4.


Since, Bond Length is directly proportional to hyperconjugable H atoms.
The bond length order follows as I>II>III.

Alkyl Halide

 Preparation of Alkyl halide : -

• From Alcohols : Reagents

• Haloacids    (HX) [where X=Halogens]
• Thionyl Chloride (SOCl2)
• Phosphorus Chloride (PCl3 or PCl5)

Reactivity of Alcohol with Haloacids : 3^o > 2^o > 1^o

The reaction of  1^o and 2^o alcohols requires a catalyst ZnCl2 to react with HX.

• Hydrohalogenation
• Halogenation
• By Free Radical Halogenation
• SANDMEYER's Reaction

Stereomerism

Asymmetric carbon atom: Carbon atom bonded with four different atoms or groups is called asymmetric carbon atom. Only sp3 can have asymmetric, neither sp² nor sp.     

      They can be of two types:-

·         Similar

·         Disimilar

If a Molecule has dissymmetry then its mirror image will be always non-superimposable and this non-superimposable mirror image will be an optical isomer.

In case of a symmetric molecule,it wil always have a superimposable mirror image.

Disymmteric

Plane polarized light vibrates in all directions but if it is passed through nicol prism(made of CaCO₃) then it vibrates only in direction. This is called plane polarized light.

Dextro Rotatory (d)(+)

Levo Rotatory (l)(-)

In every Fischer projection the two horizontal bonds are understood to be projecting out of the plane toward you and the two vertical bonds are projecting into the plane away from you.

The enantiomer of a compound can be drawn by simply drawing the mirror image of the Fischer projection

Molecules without any asymmetric center are also found to be disymmteric in some cases.

Geometrical Isomerism

Number of geometrical isomerism = 2^n, where n is the number of double bonds.

·         If n=1, then number of geometrical isomers is equal to 2(always).

·         If n>1, then number of geometrical isomers is less than or equal to 2ⁿ.

If numbering can be started from either of the two sides then number of geometrical isomers is less than 4.

If numbering can be started from only one side then number of geometrical isomers is equal to four.

Properties : -

1. Stability of Goemetrical Isomers :- Generally, trans is more stable than cis because cis isomer is more sterically crowded than trans. 

                      trans > cis          (Stability)

2. Melting Point :- It is directly proportional to van der Wall's intermolecular forces and this force is directly   proportional  to polarisibility and surface area.

Since trans has more surface area than cis trans will have higher melting point than cis.  

                       trans > cis           (m.p)

                                         

3. Solubility :- It is inversely proportional to van der Walls intermolecular force.So, cis will have more         solubility than trans.

                        cis > trans            (Solubility) 

                                  

               

Hydrocarbons

Catalyst Used	Reaction Mechanism
H2/Catalyst	Free Radical Addition
R-MgX/Ar-MgX (Heat)	Free Radical Pathway
Electrolysis	Electrolysis
Na/Dry Ether/Heat
Zn/Ether/Heat (Same as Wurtz)
R2CuLi
Clemennsen/Wolf-Kishner
Soda Lime/Heat

Preparation of Alkanes                                 

1.       Hydrogenation                      

2.       Grignard Reagent

3.       Kolbe’s Electrolysis

4.       Wurtz Reaction

5.       Frankland Reaction

6.       Corey House Alkane Synthesis

7.       Reduction of Aldehyde and Ketone

8.       Decarboxylation

Catalyst Used	Reaction Mechanism
X2/Heat	Free Radical Pathway
O2/Heat	Free Radical Pathway
Heat , SiO2/Al2O3
Ni/Heat ,Silica Alumina
HCl/AlCl3 Alkene or Alkyl Halide
HNO3/Heat NaNO2	Free Radical (Direct Nitration)
Conc. H2SO4	Carbocation
KMnO4	Radical Pathway

Properties Of Alkanes

1.       Halogenation

2.       Combustion of Alkanes                

3.       Pyrolysis or Cracking

4.       Aromatization

5.       Isomerisation

6.       Nitration of Alkanes

7.       Sulphonation of Alkanes

8.       Hydroxylation

Preparation Of Alkenes

1.       Dehalogenation

2.       Reduction From Alcohols

3.       From Alkyl halides

Properties Of Alkenes

1.       Halogenation

2.       Hydrohalogenation

3.       Hydration

4.       Hydroxylation

5.       Case of Peracid

6.       Case of KMno₄

7.       Case of Ozonolysis

8.       Allylic Halogenation

9.       Polymerisation Of Alkenes


 Preparation of Alkynes

1.       Dehydrohalogenation
2.       Dehalogenation
3.       Alkynides
4.       Isomerisation
 Properties of Alkynes                                           
1.       Halogenation
2.       Hydrohalogenation
3.       Addition of HOX
4.       Hydration(Addition Of water
            Hydroboration
           KMnO₄  Oxidation'
            Ozonolysis
8.       Propargylic Halogenation