Question

The oxidation state of the most electronegative element in the products of the reaction between \[{\text{Ba}}{{\text{O}}_2}\] and \[{{\text{H}}_2}{\text{S}}{{\text{O}}_4}\] are:
A.\[0\] and \[ - 1\]
B.\[ - 1\] and \[ - 2\]
C.\[ - 2\] and \[0\]
D.\[ - 2\] and \[ + 1\]

Answer 1

Hint:Oxidation state shows the total number of electrons which have been removed from an element with positive oxidation state or added to an element with a negative oxidation state to get its present state. Electronegativity of oxygen is greater than that of sulphur.

Complete answer:
Usually the oxidation state of oxygen is \[ - 2\] except in peroxide and \[{{\text{F}}_2}{\text{O}}\] . As in case of peroxide, it is \[{{\text{H}}_2}{{\text{O}}_2}\] , this is an electrically neutral compound and so the sum of the oxidation state of the hydrogen and oxygen must be equals to zero. Since, each hydrogen has an oxidation state of \[ + 1\] , each oxygen must have an oxidation state of \[ - 1\] to balance it. Thus, the oxidation state of oxygen in peroxide is \[ - 1\] . On the other hand, in case of \[{{\text{F}}_2}{\text{O}}\] , oxygen is not the most electronegative element. The fluorine is more electronegative and has an oxidation state of \[ - 1\] . Thus, oxygen has an oxidation state of \[ + 2\] in \[{{\text{F}}_2}{\text{O}}\].
The reaction of Barium peroxide \[{\text{Ba}}{{\text{O}}_2}\] and Sulphuric acid \[{{\text{H}}_2}{\text{S}}{{\text{O}}_4}\] produces Barium sulphate \[{\text{BaS}}{{\text{O}}_4}\] and hydrogen peroxide \[{{\text{H}}_2}{{\text{O}}_2}\] . The reaction is as follow as: \[{\text{Ba}}{{\text{O}}_2} + {{\text{H}}_2}{\text{S}}{{\text{O}}_4} \to {\text{BaS}}{{\text{O}}_4} + {{\text{H}}_2}{{\text{O}}_2}\] .
As we get two products from the reaction between Barium peroxide and Sulphuric acid, namely Barium sulphate and Hydrogen peroxide. The most electronegative element in Barium sulphate is oxygen and the oxidation state of oxygen in this compound is \[{\text{ - 2}}\] . On the other hand, the most electronegative element in the compound hydrogen peroxide is Oxygen and the oxidation state of oxygen in Hydrogen peroxide is \[ - 1\] .

Thus, the correct option is B.
Note:
Oxidation involves increase in oxidation state and reduction involves decrease in oxidation state. Electronegativity is the tendency of an element to attract the shared pair of electrons toward itself from a less electronegative element in a covalent bond.