Question

Identify the substance oxidised, reduced, oxidising agent and reducing agent for each of the following reactions:

1. \(2AgBr (s) + C_6H_6O_2(aq) \rightarrow 2Ag(s) + 2HBr (aq) + C_6H_4O_2(aq)\)
2. \(HCHO(l) + 2[Ag (NH_3)_2] ^+ (aq) + 3OH^ - (aq) \rightarrow 2Ag(s) + HCOO ^- (aq) + 4NH_3(aq) + 2H_2O(l)\)
3. \(HCHO (l) + 2Cu^{ 2+}(aq) + 5 OH^ - (aq) \rightarrow Cu_2O(s) + HCOO ^- (aq) + 3H_2O(l)\)
4. \(N_2H_4(l) + 2H_2O_2(l) \rightarrow N_2(g) + 4H_2O(l)\)
5. \(Pb(s) + PbO_2(s) + 2H_2SO_4(aq) \rightarrow  2PbSO_4(s) + 2H_2O(l)\)

Answer 1

(a) 
Oxidised substance \(\rightarrow\) \(C_6H_6O_2\) 
Reduced substance \(\rightarrow\) \(AgBr\) 
Oxidising agent \(\rightarrow\) \(AgBr\)
Reducing agent \(\rightarrow\) \(C_6H_6O_2\)

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(b)
Oxidised substance \(\rightarrow\) \(HCHO\) 
Reduced substance \(\rightarrow\) \([Ag(NH_3)_2]^+\)
Oxidising agent \(\rightarrow\) \([Ag(NH_3)_2]^+\) 
Reducing agent \(\rightarrow\) \(HCHO\)

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(c) 
Oxidised substance \(\rightarrow\) \(HCHO\) 
Reduced substance \(\rightarrow\) \(Cu ^{2+}\)
Oxidising agent \(\rightarrow\) \(Cu ^{2+}\) 
Reducing agent \(\rightarrow\) \(HCHO\)

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(d) Oxidised substance \(\rightarrow\) \(N_2H_4\) 
Reduced substance \(\rightarrow\) \(H_2O_2\) 
Oxidising agent \(\rightarrow\) \(H_2O_2\) 
Reducing agent \(\rightarrow\) \(N_2H_4\)

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(e) Oxidised substance \(\rightarrow\) \(Pb\)
Reduced substance \(\rightarrow\) \(PbO_2\) 
Oxidising agent \(\rightarrow\) \(PbO_2\)
Reducing agent \(\rightarrow\) \(Pb\)