Short Answer TypeConsider the reactions:
(a) H3PO2(aq) + 4 AgNO3(aq) + 2 H2O(l) → H3PO4(aq) + 4Ag(s) + 4HNO3(aq)
(b) H3PO2(aq) + 2CuSO4(aq) + 2H2O(l) → H3PO4(aq) + 2Cu(s) + H2SO4(aq)
(c) C6H5CHO(l) + 2[Ag (NH3)2]+(aq) + 3OH–(aq) → C6H5COO–(aq)+ 2Ag(s) +4NH3 (aq) + 2H2O(l)
(d) C6H5CHO(l) + 2Cu2+(aq) + 5OH–(aq) → No change observed.
What inference do you draw about the behaviour of Ag+ and Cu2+ from these reactions ?
Long Answer TypeDiscuss briefly the types of redox reactions. Give examples.Â
or
Discuss the following redox reactions.
(a)Â Combination reactions
(b)Â Decomposition reactions
(c)Â Displacement reactions
(d)Â Disproportionation reactions.
Give one example in each case.
Suggest a scheme of classification of the following redox reactions:
(a) N2(g) + O2(g) → 2 NO (g)
(b) 2Pb(NO3)2(s) → 2PbO(s) + 2 NO2 (g) + ½ O2 (g)
(c) NaH(s) + H2O(l) → NaOH(aq) + H2 (g)
(d)2NO2(g) + 2OH–(aq) → NO2-(aq) +NO3–(aq)+H2O(l)
(a) It is a combination redox reaction:
     0         0          +2 - 2
   N2(g)        O2(g)     
 2NO(g)
because, the compound nitric oxide is formed by the combination of the elemental substances, like nitrogen and oxygen. Since the oxidation number of nitrogen increases from 0 (in N2) to +2(in NO) and that of oxygen decreases from zero (in 02) to -2 (in NO),
hence, it is a combination redox reaction.
(b) It is a decomposition redox reaction,
because on heating lead nitrate decomposes to form a lead oxide, nitrogen dioxide and oxygen. Since the oxidation number of nitrogen decreases from +5 (in lead nitrate) to +4 (in NO2) and that of oxygen increases from -2 (in lead nitrate) to zero (in O2), hence, it is a decomposition redox reaction.
because hydrogen of water has been displaced by hydride ion to produce dihydrogen gas. Also, the oxidation number of hydrogen increases from -1 in NaH) to zero (in H2) while that of hydrogen decreases from +1 (in water) to zero (in H2), hence it is a displacement redox reaction.
(d) It is a disproportionation reaction
Because oxidation state of nitrogen decreases from +4 (In NO2) to +3 (In NO-2 ion), as well as increases from +4 (in NO2) to +5 (In NO3- ion), hence it is disproportionation reaction.
Â
Short Answer TypeRefer to the periodic table given in your book and now answer the following questions:
(a)Â Select the possible non-metals that can show disproportionation reaction.
(b)Â Select three metals that can show disproportionation reaction.
Long Answer TypeShort Answer TypeWhat sorts of informations can you draw from the following reaction?
(CN)2(g) + 2OH– (aq) → CN–(aq) + CNO–(aq) + H2O(l)
Suggest a scheme of classification of the given redox reactions,
 N2 (g) + O2 (g) 
 2NO (g)
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