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An experiment to demostrate Redox reactions involving Halide ions and halogens

Answer Text:
Redox reactions involving Halide ions and halogens
Experiment
(i). Procedure:
- 2 #cm^3# of chlorine gas are bubbled into each of the following solutions: - KI, KCl, KBr, and KF.
- The observations are made and recorded.
- The procedure is repeated using fluorine, bromine and iodine in place of chlorine.
Precaution:
- Chlorine and bromine are poisonous.
(ii). Observations

Note: Colours of halogens in tetra – chloromethane:-

(iii). Explanations
- Fluorine displaces all the other halogens; #Cl_2, Br_2 and I_2# because it has a greater tendency to accept electrons than all the rest.
- Chlorine displaces both Bromine and Iodine from their halide solutions
- #Cl_2# takes electrons from the bromide and iodide ions i.e. oxidizes them, to form bromine and iodine respectively.
Equations:
(i). Chlorine and potassium bromide:

- Bromine takes electrons form iodide ions but not from fluorine and chlorine.
- Iodine is formed i.e. due to oxidation of iodide ions by the Bromine.

Note: oxidation number of chlorine decreases from 0 to
-1 hence reduction; while oxidation number of iodine increases from -1 to 0; hence oxidation;
(iv). Conclusion:
- The stronger the tendency of an element to accept electrons, the stronger is its oxidizing power.
- Fluorine is the strongest oxidizing agent of the 4 halogens considered.