Question

Bromine is obtained commercially from sea water by adding
A. $AgN{{O}_{3}}$ ​ solution
B. Crystals of $NaBr$
C. $C{{l}_{2}}$
D. ${{C}_{2}}{{H}_{4}}$

Answer 1

Hint: The sources of bromine are carnallite and sea water. Sea water contains potassium bromide. In order to produce bromine we need the potassium bromide to react with an element/compound more reactive than bromine. Also, it is established that the reactivity of the elements decreases down the group. These reasons are important to get to the answer.

Complete Step by Step Answer:
Bromine is a halogen element. It generally exists as a yellow colored liquid. Sea water contains bromine in a potassium salt of bromine present in sea water that is potassium bromide. Potassium bromide on reaction with chlorine gas forms a salt of chlorine that is potassium chloride along with bromine gas. Thus bromine gas is extracted from sea water using chlorine gas. The reaction is given as: $C{{l}_{2}}+2KBr\to 2KCl+B{{r}_{2}}$

Thus in this reaction, two moles of potassium bromide in reaction with one mole of chlorine gas forms two moles of a salt of chlorine that is potassium chloride along with one mole of bromine gas.
Thus we can write that bromine gas is extracted from sea water using chlorine gas..
Thus the correct option is C.

Note: Bromine cannot be obtained directly from carnallite. On crystallisation carnallite produces bromine.