Plan for rate of reaction for halogenoalkanes

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Harry denis candidate No. 9038

                   Centre No. 10534

Harry Denis

Candidate No. 9038

Centre No. 10534

Plan for rate of reaction for halogenoalkanes

Aim

Aim of the experiment is to find out and compare the rate of displacement of the halide ion and how is varies with respect to the carbon halogen bond. This will occur through a nucleophilic attack.

General equation:        general formula:

R-X +: Nu-  R-Nu + X-              CnH2n+1X (where X is the halogen)

Background information halogenoalkanes

In the reaction of halogenoalkanes bond polarity show us that C-F would be the most reactive then C-CL, C-Br and C-I would be the lest reactive. This is due to the electronegativity of the halogen atoms. Electronegativity is the measure of how strongly an atom in a compound attaches electron in a bond. The greater the difference in the electronegativity of two atoms, the more polar is the covalent bond between the two atoms. So in a carbon halogen bond the halogen is more electronegative than carbon. Consequently the bond between them is polarized so the halogen atom is slightly negative.                                                 Electronegativity values

E.G.        

            H        :Nu-          H

        

   R       C+      X -                              R        C    Nu +:X-

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            H           H
According to bond enthalpy the reverse is true. Bond enthalpy shows use that C-I bond is the most reactive and the C-F bond is lest reactive. This is due to the bond energy between the atoms. Bond energy is the average standard molar enthalpy changes for the breaking of a mole of bonds in a gaseous molecule to from gaseous atoms. Bond energies indicate the strength of the forces holding together atoms in a covalent molecule. Bond energy is increased with the number of shared electron pairs. So C-I bond ...

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