Answer:
\[{{H}_{2}}{{O}_{2}}\]acts as an
oxidising agent in acidic medium.
\[{{H}_{2}}{{O}_{2}}+2{{H}^{+}}+2e\to
2{{H}_{2}}O\]
The following reactions explain
the oxidising nature of\[{{H}_{2}}{{O}_{2}}\].
(i) It oxidises acidified
ferrous sulphate to ferric sulphate.
\[2FeS{{O}_{4}}+{{H}_{2}}S{{O}_{4}}+{{H}_{2}}{{O}_{2}}\to
F{{e}_{2}}{{(S{{O}_{4}})}_{3}}+2{{H}_{2}}O\](ii) It liberates iodine from
acidified potassium iodide solution.
\[2KI+{{H}_{2}}S{{O}_{4}}+{{H}_{2}}{{O}_{2}}\to
{{K}_{2}}S{{O}_{4}}+{{I}_{2}}+2{{H}_{2}}O\]
(iii) It oxidises acidified
potassium ferro cyanide to potassium ferricyanide.
\[2{{K}_{4}}Fe{{(CN)}_{6}}+{{H}_{2}}S{{O}_{4}}+{{H}_{2}}{{O}_{2}}\to
2{{K}_{3}}Fe{{(CN)}_{6}}\] \[+{{K}_{2}}S{{O}_{4}}+2{{H}_{2}}O\]
\[{{H}_{2}}{{O}_{2}}\]also acts
as a reducing agent in acidic medium.
\[{{H}_{2}}{{O}_{2}}\to
2{{H}^{+}}+{{O}_{2}}+2e\]
or \[{{H}_{2}}{{O}_{2}}+O\to
{{H}_{2}}O+{{O}_{2}}\]
(from oxidising agent)
The following reactions explain
the reducing nature of\[{{H}_{2}}{{O}_{2}}\].
(i) It reduces acidified \[KMn{{O}_{4}}\]
solution. \[2KMn{{O}_{4}}+3{{H}_{2}}S{{O}_{4}}+5{{H}_{2}}{{O}_{2}}\to
{{K}_{2}}S{{O}_{4}}+2MnS{{O}_{4}}+8{{H}_{2}}O+5{{O}_{2}}\](ii) It reduces
manganese dioxide in presence of dilute\[{{H}_{2}}S{{O}_{4}}.\]
\[Mn{{O}_{2}}+{{H}_{2}}S{{O}_{4}}+{{H}_{2}}{{O}_{2}}\to
MnS{{O}_{4}}+2{{H}_{2}}O+{{O}_{2}}\]
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