Question

the student claims that the reaction is an oxidation - reduction reaction. which of the following statements correctly describes a change in oxidation number as the decomposition reaction proceeds?
a the oxidation number of hydrogen changes from + 2 to + 1
b the oxidation number of hydrogen changes from + 1 to + 2
c the oxidation number of oxygen changes from - 2 to - 1
d the oxidation number of oxygen changes from - 1 to 0

Explanation:

Step1: Recall the decomposition reaction of hydrogen peroxide

The decomposition reaction of hydrogen peroxide is \(2H_{2}O_{2}
ightarrow 2H_{2}O + O_{2}\uparrow\).

Step2: Calculate the oxidation number of hydrogen

In \(H_{2}O_{2}\) and \(H_{2}O\), hydrogen has an oxidation number of \(+ 1\). So options A and B are wrong.

Step3: Calculate the oxidation number of oxygen

In \(H_{2}O_{2}\), let the oxidation number of \(O\) be \(x\). Using the rule that the sum of oxidation numbers in a compound is zero (\(2\times( + 1)+2x = 0\)), we get \(x=-1\). In \(O_{2}\), the oxidation number of \(O\) is \(0\). In \(H_{2}O\), let the oxidation number of \(O\) be \(y\). Using \(2\times( + 1)+y = 0\), we get \(y = - 2\).

Answer:

D. The oxidation number of oxygen changes from \(-1\) to \(0\)