Question

Mixtures of $KBr$ and \[KBr{{O}_{3}}\] ​in acidic medium can be used as brominating agents.
The chemical reaction is, \[5B{{r}^{-}}+xBr{{O}_{3}}^{-}+6{{H}^{+}}\to 3B{{r}_{y}}+3{{H}_{2}}O\]
Then x+y is :
A. 6
B. 3
C. 5
D. 11

Answer 1

Hint: Chemical formula gives us the information about the total number of atoms in a molecule of the compound, the number of various atoms in 1 molecule of the compound, composition of the molecules of the compound but not about the state of the molecules of the compound.

Complete step by step solution:
- The reaction of the same 2 compounds can result in different products depending on several factors like the concentration of the reactants, temperature of the reaction, pressure of the reaction and certain catalysts.
-Order of a reaction is responsible for the type of reaction that occurs between the different products. It decides the mechanism of the reaction and so different products obtained through the reactants are the same.
-Same thing occurs in this reaction. Bromine has vacant d-orbitals and so it can have variable covalencies. There are 7 electrons in normal state in bromine molecules. In different excitation states, its covalencies change.
-One bromine atom oxidizes and the other atom reduces and so different products are formed which have different oxidation states. So here we see that the same atom is oxidized as well as reduced and so it is called auto or self redox reaction.
-Thus we see that bromine can have different oxidation states and this makes it capable of forming different compounds with different products. The reaction can be shown as
\[5B{{r}^{-}}+Br{{O}_{3}}^{-}+6{{H}^{+}}\to 3B{{r}_{2}}+3{{H}_{2}}O\]
-Comparing this equation with the equation \[5B{{r}^{-}}+xBr{{O}_{3}}^{-}+6{{H}^{+}}\to 3B{{r}_{y}}+3{{H}_{2}}O\], we see that
The value of x=1 and the value of y=2. Thus we get x+y=1+2=3.

Therefore the answer is 3 and the correct option is B.

Note: The bromine atom present in the compounds of K can be reduced and oxidized both. So they act as good brominating agents as both the compounds lead to the formation of bromine, one by oxidation and the other by reduction.