question_answer 23)

Identify the substances oxidised, reduced, oxidizing agents and reducing agents for each of the following reactions. (a) \[2AgBr(s)+{{C}_{6}}{{H}_{6}}{{O}_{2}}(aq)\to 2Ag(s)+2HBr(aq)\] \[+{{C}_{6}}{{H}_{4}}{{O}_{2}}(aq)\] (b) \[HCHO(l)+2{{[Ag{{(N{{H}_{3}})}_{2}}]}^{+}}(aq)+3O{{H}^{-}}(aq)\] \[\to 2Ag(s)+HCO{{O}^{-}}(aq)+4N{{H}_{3}}(aq)+2{{H}_{2}}O(l)\](c) \[HCHO(l)2C{{u}^{2+}}(aq)+5O{{H}^{-}}\to C{{u}_{2}}O(s)\] \[+HCO{{O}^{-}}(aq)+3{{H}_{2}}O(l)\] (d) \[{{N}_{2}}{{H}_{4}}(l)2{{H}_{2}}O(l)\to {{N}_{2}}(g)+4{{H}_{2}}O(l)\] \[(e)Pb(s)Pb{{O}_{2}}(s)+2{{H}_{2}}S{{O}_{4}}(aq)\to 2PbS{{O}_{4}}(s)+2{{H}_{2}}O(l)\]

Answer:

(a) ln\[AgBr,A{{g}^{+}}\]is reduced to Ag. \[AgBr\]is oxidising agent. In \[{{C}_{6}}{{H}_{6}}{{O}_{2}},\]carbon is oxidised \[{{C}_{6}}{{H}_{6}}{{O}_{2}}\]is reducing agent (b) \[HCHO\]is oxidised to \[HCO{{O}^{-}}\]   \[HCHO\]is reducing agent. \[{{[Ag{{(N{{H}_{3}})}_{2}}]}^{+}}\]is reduced to Ag. \[{{[Ag{{(N{{H}_{3}})}_{2}}]}^{+}}\]is oxidising agent. (c) \[HCHO\]is oxidised to \[HCO{{O}^{-}}\].   \[HCHO\]is reducing agent. \[C{{u}^{2+}}\]is reduced to \[C{{u}^{+}}\]\[(C{{u}_{2}}O).\] \[C{{u}^{2+}}\]is oxidising agent. (d) \[{{N}_{2}}{{H}_{4}}\]is oxidised to \[{{N}_{2}}\](loss of hydrogen)   \[{{N}_{2}}{{H}_{4}}\]is reducing agent.     \[{{H}_{2}}{{O}_{2}}\]is reduced to \[{{H}_{2}}O\] \[{{H}_{2}}{{O}_{2}}\]is oxidising agent. (e) \[\overset{0}{\mathop{Pb}}\,(s)\]is oxidised to \[\overset{2+}{\mathop{Pb}}\,SO_{4}^{2-}\]. \[Pb\]is reducing agent. \[\overset{+4-4}{\mathop{Pb{{O}_{2}}}}\,\]is reduced to \[\overset{+4-4}{\mathop{PbSO_{4}^{2-}}}\,\] \[Pb{{O}_{2}}\]is oxidising agent.