Alcohols

                    Alcohols

Hydrocarbons are the parents of other organic compounds. When One or more hydrogen atoms are replaced by the different types of atoms or group of atoms from hydrocarbons then different types of organic compounds are formed .
           When hydrogen atoms are replaced from saturated aliphatic hydrocarbons by the hydroxyl group (-OH) ,then Alcohols are formed.
  For example-

                -H
  R-H ------------->    R-OH                                +OH

Where R is the alkAl group.

                   -H
 CH3-H ------------->     CH3-OH                         +OH              (Methanol)


So, Hydroxy derivatives of the aliphatic hydrocarbons are known as Alcohols.



Classification of Alcohols-

Hydroxy derivatives of the aliphatic hydrocarbons are known as Alcohols.
The general formula of the alcohols are R-OH. Where R is the Alkyl group.

Alcohols are classified on the basis of the number of the Hydroxyl groups (-OH) attached to the alkAl group.


(1) Monohydric Alcohols -

In the monohydric alcohols only one Hydroxyl group (-OH) attached to the alkAl group. The general formula of the monohydric alcohols are CnH2n+1OH or ROH.
   These are further classified as follows-

(A) Primary alcohols-

Those alcohols in which -OH group is attached to the 1° carbon atom is called primary alcohols.

For example-

           H

           |1°

      H-C-OH    (Methyl alcohol)

          |
          H

               H 

               |1°

      CH3-C-OH    (Ethyl alcohol)

               |
               H

(B) Secondary alcohols-

Those alcohols in which -OH group is attached to the 2° carbon atom is called secondary alcohols.

For example-

           CH3

           |2°

  CH3-C-OH    (Isopropyl alcohol)

           |
           H

  (C) Tertiary alcohols-

Those alcohols in which -OH group is attached to the 3° carbon atom is called tertiary alcohols.

For example-

           CH3

           |3°

  CH3-C-OH    (tert.butyl alcohol)

           |
           CH3

     

(2) Dihydric alcohols-

These are generally called as Glycol . The general formula of the Dihydric alcohols are (CH2)n(OH)2 , where n= 2,3,4 etc.
In this type of the alcohols 2--OH groups are attached to the two different carbon atoms.
For example-


  HO-CH2CH2-OH
 (Ethane-1,2-diol)


   CH3-CHOH-CH2-OH
  (Propane-1,2-diol)

(3) Trihydric alcohols-

In this type of the alcohols 3--OH groups are attached to the three different carbon atoms. In I.U.P.A.C. system these are known as alkanetriol.
For example-

     CH2-OH
     |
     CH-OH
     |
     CH2-OH
   
( Propane-1,2,3-triol)
Or Glycerol

Nomenclature of Haloalkanes

Nomenclature of Haloalkanes

The name of the haloalkanes are given by two different ways-

(1)Trivial or common system-

In this system haloalkanes are known as Alkyl halide.

       There nomenclature are performed by the adding halide word in the given alkyl group. In this system the name of the compound is written in the two different words.
   For example-
    CH3-Cl          (Methyl chloride)
CH3-CH2-Br     (ethyl bromide)                    

Prifixes of the different types of alkyl group-

(a) prefix- n

The means of prefix-n is normal. This is used in the straight chain of the Alkyl group.
 For example-

 CH3-CH2-CH2-Br                          (n-propyl bromide)


(b) prefix- iso

Prefix-iso is used for those Alkyl group in which methyl (--CH3) branch is present in the last of the chain.
For example-

CH3-CH-Br

         |

         CH3
  (Isopropyl bromide)


(c) prefix- neo


Prefix-neo is used for those Alkyl group in which two methyl (--CH3) group is attached in the last of the chain by a single carbon atom.
For example-

         CH3
         |
CH3-C-Br

         |

         CH3
  (neo butyl bromide)

(2) I.U.P.A.C. system-

In this system the monohalogen derivatives of the alkane is written as haloalkane.
For the naming of haloalkanes, fluoro, chloro, bromo or iodo prefix is writes before the longest carbon chain.
   The numbering is starts from the nearest halogen atom of the chain.
   The I.U.P.A.C. name of the haloalkanes is always writes in a single word.
  For example-

  CH3-CH-CH2-Br
           |
           CH3
   (1-bromo-2-methylpropane)



         CH3
         |
CH3-C-CH2-CH2-I
         |
         CH3
   (1-iodo-3,3-dimethylbutane)

Haloalkanes and Haloarenes

 Haloalkanes and Haloarenes

Haloalkanes- 
The word Haloalkane is made up by the two words, -
         Halo = halogen
         Alkane= Aliphatic hydrocarbon (containing single bond only)

So, Haloalkanes are those compounds which is formed when a hydrogen atom replaced by any halogen atom from the alkanes.

               - H
   R-H  -------------->      R-X
                +X

Where ,   R  =  Alkyl group
              X  = Halogen ( F,Cl, Br, I)
For example-
   
                           - H
         CH3-H  --------------> CH3-Cl
                           +Cl


Haloarenes- 
The word Haloarene is made up by the two words, -
         Halo = halogen
   Arene= Aromatic hydrocarbon

So, Haloarenes are those compounds which is formed when a hydrogen atom replaced by any halogen atom from the arenes.

               - H
   Ar-H  -------------->      Ar-X
                +X

Where ,  Ar  =  Aromatic hydrocarbon
              X  = Halogen ( F,Cl, Br, I)
For example-
   
                           - H
         C6H5-H  --------------> C6H5-Cl
                           +Cl


Classification of Halogen derivatives of Hydrocarbon -

(A) On the basis of Nature of carbon chain - 
On this basis the Halogen derivatives of Hydrocarbons are of two types :-
(1) Aliphatic Halogen Compounds  -

Aliphatic Halogen Compounds are divided into three groups-

(a) Haloalkanes - The Halogen derivatives of the alkanes are called Haloalkanes.
These are called mono, di ,tri, tetra or polyhaloalkane on the number of hydrogen atom replaced by a halogen atom.
 For example-

         H
         |
    H-C-Cl     ( ChloroMethane)
         |
         H


         H
         |
    H-C-Cl     ( diChloroMethane)
         |
         Cl


         Cl
         |
    H-C-Cl     (tri ChloroMethane)
         |
         Cl

         Cl

         |
    Cl-C-Cl  ( tetra ChloroMethane)
         |
         Cl

Mono Halogen derivatives are also called alkyl halides or Haloalkanes.

Classification of alkyl halides-

(|) Primary (1°) alkyl halide - 

When Halogen atom is attached by 1° carbon atom is known as primary alkyl halide.
   For example-


         H
         |
    H-C-Cl     ( ChloroMethane)
         |
         H

(||) Secondary (2°) alkyl halide - 

When Halogen atom is attached by 2° carbon atom is known as secondary alkyl halide.
   For example-


             H
             |
    CH3-C-Cl  ( 2-ChloroPropane)
             |
             CH3

(|||) Tertiary (3°) alkyl halide - 

When Halogen atom is attached by 3° carbon atom is known as tertiary alkyl halide.
   For example-


             C H3
             |
    CH3-C-Cl  ( 2-Chloro 2- methyl
             |            Propane)
             CH3

(b) Haloalkenes - The Halogen derivatives of the alkenes are called Haloalkenes. 

For example-

CH2=CH-Cl    ( Chloroethene)

(c) Haloalkynes - The Halogen derivatives of the alkynes are called Haloalkynes. 

For example-

      _ 

CH=C-Cl    ( Chloroethyne)

(2) AromaticHalogen Compounds  -

Aromatic Halogen Compounds are divided into two groups-

(a) Nuclear Halogen derivatives-

When one or more hydrogen atom are replaced by one or more Halogen atom from an aromatic ring then formed compound is called nuclear halogen derivative or Haloarene or aryl halide.
For example-
  C6H5-Cl     ( chlorobenzene)


(b) Side chain  Halogen derivatives-

When one or more hydrogen atom are replaced by one or more Halogen atom from a side chain of aromatic ring then formed compound is called side chain halogen derivative or  aryl alkyl halide.
For example-
       C6H5CH2-Cl           
  ( Phenyl chloro methane )



(B) On the basis of hybridisation of the C -X bond-   




(a) Csp3--- bond containing compounds-


In this type of monohalogen Compounds , the halogen atom is attached to the directly to the sp3 hybridised carbon atom.

(1) Haloalkane or alkyl halide -
In Haloalkane , Halogen atom is attached to the alkyl group (R) . These are further divided into primary (1°), secondary (2°) , or tertiary (3°) .

For example-


         H
         |
    H-C-Cl     ( ChloroMethane)                   (1°)
         |
         H

             H
             |
    CH3-C-Cl  ( 2-ChloroPropane)               (2°)
             |

             CH3

             C H3

             |

    CH3-C-Cl  ( 2-Chloro 2- methyl             

             |            Propane)                             (3°)

             CH3

(2) Alylic halide-
In this type of halides, the halogen atom is attached to the next carbon ( sp3) of carbon - carbon double bond ( C= C).
For example -
   CH2 = CH- CH2-X

(3) Benzylic halide-

In this type of halides, the halogen atom is attached to the next carbon ( sp3) of  aromatic ring.
For example
 C6H5-CH2-Cl

(b) Csp2--- bond containing compounds-

In this type of monohalogen Compounds , the halogen atom is attached to the directly to the sp2  hybridised carbon atom(C=C).

(1) Vinylic halide-
In this type of halides, the halogen atom is attached to the sp2 hybridised carbon - carbon double bond ( C= C).
For example -
   CH2 = CH-X

(2) Aryl halide-
In this type of halides, the halogen atom is attached to the directly aromatic ring.
For example -

C6H5-Cl

(c) Csp--- bond containing compounds-

In this type of monohalogen Compounds , the halogen atom is attached to the directly to the sp  hybridised carbon atom(C-C triple bond).

For example-

       _

H-C=C-Cl

Allotropes of carbon

           Allotropes of carbon

 The various physical forms in which an element can exist are called allotropes of the element. The carbon elements exists in three solid forms called allotropes. The three allotropes of the carbon are -
(1) Diamond
(2) Graphite
(3) Buckminster fullerene

              (1) Diamond

Diamond is a colourless transparent substance having extraordinary shining. Diamond is quite heavy. Diamond is extremely hard. It is the hardest natural substance known. Diamond does not cunduct electricity. Diamond burns on strong heating to form carbon dioxide. If we burn diamond in Oxygen , then only CO2 gas is formed and nothing is left behind. This shows that diamond is made up of carbon only.

Structure of Diamond - 

A Diamond crystal is a very big molecule of carbon atoms. Each carbon atom in the diamond crystal is linked to four other carbon atoms by strong covalent bonds. The four surrounding carbon atoms are at the four vertices of a regular tetrahedron.

        The diamond crystal is, therefore, made up of carbon atoms which are powerfully bonded to one another by a network of covalent bonds. Due to this, diamond structure is very rigid. The rigid structure of Diamond makes it a very hard substance. The compact and rigid three dimensional arrangements of carbon atoms in diamond gives it a high density. The melting point of diamond is also very high. Diamond is a non conductor of electricity.

Uses of Diamond - 
(1) Diamonds are used in cutting instruments like glass cutters, saw for cutting marble and in rock drilling equipment.
(2) Diamonds are used for making jewellery.
(3) Sharp edged diamonds are used by eye surgeons as a tool to remove cataract from eyes with a great precision.

             (2) Graphite

Graphite is a greyish - black opaque substance. Graphite is lighter than diamond. Graphite is soft and slippery to touch. Graphite conductes electricity. Graphite burns on strong heating to form carbon dioxide. If we burn graphite in Oxygen,then only carbon dioxide gas is formed and nothing is left behind. This shows that graphite is made up of carbon only.

Structure of graphite - 


The structure of graphite is very different from that of diamond. A graphite crystal consists of layers of carbon atoms or sheets of carbon atoms.

          Each carbon atom in a graphite layer is joined to three other carbon atoms by strong covalent bonds to form flat hexagonal rings. The various layers of carbon atoms in graphite are quite far apart so that no covalent bonds can exist between them. The various layers of carbon atoms in graphite are held together by weak van der Waals forces. Due to the sheet like structure, graphite is a comparatively soft substance. Graphite is a good conductor of electricity , due to the presence of free electrons .

Uses of Graphite- 
(1) Due to its softness, powdered graphite is used as a lubricant for the fast moving parts of the machinery.
(2) Graphite is used for making carbon electrodes in dry cells and electric arcs.
(3) Graphite is used for making the cores of our pencils called pencil leads and black paints.


       (3) Buckminster fullerene

Buckminster fullerene is an allotrope of carbon Containing clusters of 60 carbon atoms joined together to form spherical molecules. Since there are 60 carbon atoms in a molecule of Buckminster fullerene ,so its formula is C60
( C- sixty ) .
Structure of Buckminster fullerene - 

Buckminster fullerene is a football shaped spherical molecule in which 60 carbon atoms are arranged in interlocking hexagonal and pentagonal rings of carbon atoms. There are 20 hexagons and 12 pentagons of carbon atoms in one molecule of Buckminster fullerene .

    This allotrope was named Buckminster fullerene after the American architect Buckminster Fuller because its structure resembled the framework of domeshaped halls designed by Fuller for large international exhibitions .

Buckminster fullerene is a dark solid at room temperature. Just like diamond and graphite, Buckminster fullerene also burns on heating to form carbon dioxide. If we burn Buckminster fullerene in Oxygen then only carbon dioxide is formed and nothing is left behind. This shows that buckmbuckmi is made up of carbon only. Buckminster fullerene is neither very hard nor soft.
 Other properties of Buckminster fullerene are still being investigated.

Acids

      Acids

*Acids are those compounds 

  which gives Hydrogen ions (H+ ion) in aqueous solutions.

For example-

       HCl --------> H+    +  Cl`

       (aq)            (aq)       (aq)

* Acids are those compounds which makes hydronium ions in aqueous solutions.

For example-

          HCl --------> H+    +  Cl`

       (aq)            (aq)       (aq)

H+  +   H2O ------->  H3O+

                           (Hydronium ion)

* Acids are those compounds which is reacts with bases and form salts and water.

For example-

NaOH  +  HCl -------> NaCl +H2O

(Base)     (Acid)      (Salt)   (Water)

* Acids are those compounds which are sour  in taste.

  For example- citric acid , lactic acid etc.

*Organic acids and mineral acids-

(1)Organic acids-  The acids present in plant materials and animals are called organic acids.

 For example- Acetic acid, formic acid etc.

(2)Inorganic acids-  The acids prepared from the minerals of the earth are called mineral acids.

 For example- HCl,  H2SO4 , HNO3 etc.

*Strong acids and weak acids-

(1) Strong acids-   The acids which gives maximum number of the Hydrogen ions in the aqueous solutions are called strong acids. 

All the mineral acids are strong acids.( Exception Carbonic acid)

For example- HCl,  H2SO4 , HNO3 etc.

 (2)Weak acids-    The acids which gives minimum number of the Hydrogen ions in the aqueous solutions are called weak acids. 

All the Organic acids are weak acids.

For example- citric acid, lactic acid etc.

*Concentrated acids and Dilute acids-

(1) Concentrated acids-  A concentrated acid is one which contains the minimum possible amount of water in it.

(2) Dilute acids-  A dilute acid is one which contains much more of water in it.

Properties of acids-

(1) Acids have a sour taste.

(2) Acids turn blue litmus to red.

(3) Acid solutions conduct electricity.

(4) Acids reacts with metals to form hydrogen gas.

    Zn  +  H2SO4 ------> ZnSO4 + H2

(5) Acids reacts with metal carbonates and metal hydrogen carbonates to form carbon dioxide ( CO2) gas.

  Na2CO3 + 2HCl ------> 2NaCl + CO2 + H2O 

(6) Acids reacts with bases to form salts and water.

  NaOH + HCl ------> NaCl + H2O 

(7) Acids reacts with metal oxides to form salts and water.

  CuO + 2HCl ------> CuCl2 + H2O

(8) Acids have corrosive nature.

Dalton's atomic theory

Dalton's atomic theory 

The theory that all matters is made up of very tiny indivisible particles (atoms) is called atomic theory of matter. Dalton put forward his atomic theory of matter in 1808.

      The various postulates or assumptions of Dalton's atomic theory of matter are as follows-

(1) All the matter is made up of very tiny particles called atoms.

(2) Atoms cannot be divided.

(3) Atoms can neither be created nor be destroyed.

(4) Atoms are of various kinds. There are as many kinds of atoms as are elements.

(5) All the atoms of a given element are identical in every respect, having the same mass, size and chemical properties.

(6) Atoms of different elements differ in mass, size and chemical properties.

(7) Chemical combination between two or more elements consists in the joining together of atoms of these elements to form molecules of compounds.

(8) The numbers and kind of atoms in a given compound is fixed.

(9) During chemical combination,atom a of different elements combine in small whole numbers to form compounds.

(10) Atoms of same elements can combine in more than one ratio to form more than one compound.

           Dalton's atomic theory was the first modern attempt to describe the behaviour of matter in terms of atoms. This theory was also used to explain the laws of chemical combination.

Drawbacks of Dalton's atomic theory-

 It is now known that some of the statement of  Dalton's atomic theory of matter are not exactly correct. Some of the drawbacks of the Dalton's atomic theory of matter are given below-

(1) one of the major drawback of Dalton's atomic theory  of matter is that atoms were thought to be indivisible ( which cannot be divided). We know that under special circumstances, atoms can be further divided into still smaller particles called electrons , protons and neutrons.

(2) Dalton's atomic theory says that all the atoms of an element have exactly the same mass. It is, however, now known that atoms of the same element can have slightly different masses.

(3) Dalton's atomic theory says that atoms of different elements have different masses. It is however now known that even atoms of different elements can have the same mass.

                John Dalton

 John Dalton was born in 1766 in a poor weaver's family in England. He received his early education from his father and at the village school. Dalton started teaching in the village at the age of 12 . In 1793 , Dalton left for Manchester to teach physics,chemistry and mathematics in a college. In 1794 , he described colour blindness. In 1808 , Dalton presented his atomic theory to explain the properties of matter. Dalton was the first to calculate the masses of the atoms of several elements. He died in 1844.

The Gas laws

  The Gas laws 

(A) Boyle's law -

 This law is given by the scientist Robert Boyle in 1662.

According to this law-

 The volume of a given mass of a gas is inversely proportional to its pressure provided the temperature remains constant.

   

                                                                           1                                           v     =    -----                 ( at constant                 p                temperature)  

                          

Or,     pv =  k = constant

Let the pressure and volume of any  gas is p   and V  and the 

                     1            1

 pressure and volume    of the same amount of the same gas be p  and v      then -

  2          2  

    p   v    =   p    v  = constant

      1    1         2    2

 (B) Charles' law-

   This law is given by the scientist J. Charles in 1787.

According to this law-

At constant pressure, the volume of a given mass of a gas is directly proportional to its absolute temperature.

     V   ~  T  (at constant pressure)

Or,    V = kT

               V 

 Or,       ----  = k

               T 

                V         V 

                  1          2

Or,        ------  =  -----

                T           T 

                  1            2

 (C) Gay Lussac's law-

 This law is given by the scientist Gay Lussac in 1802.

According to this law-

     At constant volume, the pressure of a given mass of a gas is directly proportional to its absolute temperature.

   P ~  T ( at constant volume)

Or,    P = kT

               P 

 Or,       ----  = k

               T 

                P          P

                  1          2

Or,        ------  =  -----

                T           T 

                   1           2

 (D) Avogadro's law-

This law is given by the scientist Amedeo Avogadro in 1811.

According to this law-

     Equal volume of all gasses contain equal number of molecules under similar conditions of temperature and pressure.

  

   V   ~  n

                V         V 

                  1          2

Or,        ------  =  -----

                n           n

                  1            2

Laws of chemical combination

Laws of chemical combination

(1)Laws of conservation of mass-

 This law is given by the French scientist A. Lavosier in 1774. 

          According to this law-

In any physical or chemical change the total mass of the products is always equal to the total mass of the reactants.

This law is also represents as -

Matter is neither be created nor be destroyed in any physical or chemical change but it transformed into one form to another form.

  

For example-

   2H2O  ------> 2H2  + O2

  36 gram      4 gram   32 gram

(2)Law of constant proportion-

This law is given by the French scientist Proust in 1799. 

          According to this law-

In any chemical compound , the elements presents in the compound are always present in a fixed proportion by mass.

  For example-

(a)In the compound CO2 the ratio of Carbon and Oxygen is always found in the 3:8 by mass.

(b) In the compound H2O the ratio of Hydrogen and Oxygen is always found in the 1:8 by mass.

(3)Law of Multiple proportion-

 This law is given by the scientist John Dalton in 1804. 

          According to this law-

When two elements are combined to each other and form two or more than two compound then mass of one element which is combined to the fixed mass of other element,is found in a simple ratio.

For example-

Two elements Carbon and Oxygen formed Carbon mono oxide(CO) and carbon dioxide (CO2) after the combination of each other. In the carbon monoxide the ratio by mass of C and O is 12:16. On the other hand the ratio of C and O in CO2 is 12:32. So the fixed mass of carbon (12part) is reacts with different - different mass of Oxygen. So in the both compounds the ratio by mass of the oxygen is 16:32 or 1:2 .

(4) Law of Reciprocal proportion-

This law is given by the German scientist Ritcher in 1792. 

          According to this law-

When the two elements are combined with different ways by the fixed mass of the third element then the same ratio or its a multiple ratio by mass is found in which they are combined to each other.

For example-

Let in the three elements Hydrogen (H) , Sulpher(S) and Oxygen (O) , H and O formed H2O , S and O formed SO2 , H and S formed H2S.

         The ratio of H, O in H2O is 2:16 or 4:32 whereas the ratio of S and O in the SO2 is 32:32.

              So ratio of H and S which is combined with the fixed mass (32 part) of oxygen is 4:32 or 1:8.   ....................(i)

            When H and S formed H2S ,then the ratio of H and S is 2:32 or 1:16  ................................(ii)

 So the ratio of (i) and (ii) is-

   1        1

  ----  :  -----   Or   2:1

    8       16

So, they are present in the simple ratio.

(5) Gay Lussac's Law -

This law is given by the scientist Gay Lussac in 1808.

          According to this law-

When the gasses are chemically combined with each other then the volume of reactants and the volume of the products are found in the simple ratio when the temperature and pressure are fixed.

For example-

 H2(g)   +     Cl2(g)  ------->  2HCl(g)

1volume   1 volume       2 volume

उत्प्रेरण (Catalysis )

                 उत्प्रेरण (Catalysis )
 रासायनिक अभिक्रियाओं की गति किसी विशिष्ठ पदार्थ की थोड़ी सी मात्रा की उपश्थिति से प्रभावित हो सकती है | इस प्रकार के पदार्थो को उत्प्रेरक कहा जाता है तथा इस घटना को उत्प्रेरण कहते हैं | उत्प्रेरण पद को सर्वप्रथम बर्जीलियस ने सन 1836 में प्रयोग किया था |

(A) धनात्मक उत्प्रेरण ( positive catalysis )-
 वे उत्प्रेरक जो अभिक्रिया के वेग को बढ़ा देते हैं उन्हें धनात्मक उत्प्रेरक कहा जाता है तथा इस घटना को धनात्मक उत्प्रेरण कहते हैं |
जैसे -
                       Pt
        2H2O2 --------> 2H2O + O2


(B) ऋणात्मक उत्प्रेरण ( Negative 
catalysis )-
 वे उत्प्रेरक जो अभिक्रिया के वेग को घटा  देते हैं उन्हें ऋणात्मक उत्प्रेरक कहा जाता है तथा इस घटना को ऋणात्मक उत्प्रेरण कहते हैं |
जैसे -
टेट्रा एथिल लेड (TEL ) की उपश्तिथि द्वारा पेट्रोल का अपस्फोटन कम हो जाता है |

     उत्प्रेरण के प्रकार ( Types of Catalysis )

(1) समांग उत्प्रेरण (Homogeneous catalysis )--
  जब उत्प्रेरक व अभिकारक एक ही प्रावस्था में स्थित होते हैं तथा अभिक्रिया तंत्र पूर्णतः समांग होता है तो इस प्रकार के उत्प्रेरण को समांग उत्प्रेरण कहा जाता है |
जैसे -
                               NO (g)       2SO2(g)  + O2(g)-----------> 2SO3 (g)


(2) विषमांग उत्प्रेरण (Heterogeneous catalysis )--
  जब उत्प्रेरक व अभिकारक भिन्न भिन्न   प्रावस्था में स्थित होते हैं तथा अभिक्रिया तंत्र पूर्णतः विषमांग होता है तो इस प्रकार के उत्प्रेरण को विषमांग उत्प्रेरण कहा जाता है |
जैसे -
                               Pt (s)       2SO2(g)  + O2(g)-----------> 2SO3 (g)

(3) स्वतः उत्प्रेरण (Auto catalysis )--
  जब किसी रासायनिक अभिक्रया में कोई उत्पाद ही उत्प्रेरक का कार्य करता है तो इस घटना को स्वतः उत्प्रेरण कहते हैं |
जैसे -
CH3COOC2H5 + H2O ---------> CH3COOH + C2H5OH

(4) प्रेरित उत्प्रेरण (Induced catalysis )--
  जब एक रासायनिक अभिक्रिया सामान्य परिश्थितियों में संपन्न न होने वाली एक अन्य रासायनिक अभिक्रिया के वेग को प्रभावित करती है तो इस घटना को प्रेरित उत्प्रेरण कहा जाता है |
जैसे -
ऑक्सेलिक अम्ल के साथ मरक्यूरिक क्लोराइड का अपचयन


(5) एंजाइम  उत्प्रेरण (Enzyme catalysis )--
 जब कोई रासायनिक अभिक्रिया किसी एंजाइम के द्वारा उत्प्रेरित होता है तो इसे एंजाइम उत्प्रेरण कहते हैं |
जैसे - टायलिन एंजाइम द्वारा स्टार्च का माल्टोस में परिवर्तन

वांट हॉफ कारक (van't Hoff factor )

वांट हॉफ कारक(van't Hoff factor )
वांट हॉफ (1886) ने विलेय पदार्थो के आणविक संयोजन तथा वियोजन का विस्तृत अध्ध्यन किया तथा विलेय पदार्थ के विलयन में संयोजन या वियोजन की सीमा को व्यक्त करने के लिए एक कारक i की कल्पना की | इस कारक को वांट हॉफ कारक कहते हैं | इसे निम्न प्रकार परिभाषित किया जा सकता है -
किसी अणुसंख्य गुणधर्म के प्रायोगिक मान (observed value ) तथा सामान्य मान (calculated value ) के अनुपात को वांट हॉफ कारक i कहा जाता है |
गणितीय रूप में,
     किसी अणुसंख्य गुणधर्म का प्रायोगिक                       मान (observed value )
i =  --------------------------------------------
      किसी अणुसंख्य गुणधर्म का  सामान्य             मान (calculated value )

                        ∆
                          obs
 या,        i =    ------------
                        ∆
                          cal

वाष्प दाब में अवनमन के लिए,
                   (∆p)
                          obs
          i =    ------------
                   ( ∆p)
                           cal

क्वथनांक में उन्नयन के लिए,
                  (∆T)
                          obs
          i =    ------------
                   ( ∆T)
                           cal

हिमांक में अवनमन के लिए ,
         

                  (∆T)
                          obs
          i =    ------------
                   ( ∆T)
                           cal

परासरण दाब के लिए ,
       

                        π
                          obs
          i =     ------------
                         π
                           cal