Question

What is the action of chlorine on the following?
(A) Cold and dilute caustic soda
(B) Hot and concentrated caustic soda
(C) Potassium bromide solution

Answer 1

Hint : Chlorine is a p block element which belongs to the group seventeen. It has seven electrons in its outermost orbital. These seven electrons have only one of the electrons to be unpaired. Chlorine is used for various purposes in the industry.

Complete Step By Step Answer:
Chlorine belongs to the p block element and it has seven electrons in its outermost electrons.
Now an element can lose or gain electrons on the basis of their tendency to lose electrons, that is their electronegativity with respect to the solution or the compound it is reacting with. The basic nature of oxides of the elements also decreases from left to right on the periodic table and also the acidic nature increases. In presence of solutions of strong bases, they act as ace and form compounds with them, forming its oxide.
Caustic soda is also called sodium hydroxide. Sodium hydroxide is a very strong base which reacts as a base.
Now dilute caustic soda is a fairly basic solution, during this the chlorine loses one electron and goes in the positive oxidation state and makes the reaction $C{l_2} + NaOH(dil) \to NaOCl + NaCl + {H_2}O$
Now here chlorine loses one electron while gains one electron in another compound. It exists in two oxidation states, one positive and one negative.
Now when hot and concentrated caustic soda is highly basic in those conditions, during this chlorine loses five electrons readily in the presence of highly electronegative oxygen in concentrated solution. The reaction goes as follows
$C{l_2} + NaOH(conc) \to NaOC{l_3} + NaCl + {H_2}O$
Now here chlorine loses five electrons in one compound and gains one eel citron in another compound.
Now when chlorine reacts with potassium bromide, bromine is less electronegative than chlorine, therefore here a displacement reaction will take place.
$C{l_2} + KBr \to KCl + B{r_2}$
Now here chlorine gains just one electron displacing bromine from potassium bromide.

Note :
Chlorine is used vastly in the industry processes. It is used to kill bacteria, as a disinfectant. It is used to treat drinking water and swimming pool water. It is also used in the paint industry and paper industry. They are also used to make insecticides.