Consider the reactions:

(a) H3PO2(aq) + 4 AgNO3(aq) + 2 H2O(l) → H3PO4(aq) + 4Ag(s) + 4HNO3(aq)


(b) H3PO2(aq) + 2CuSO4(aq) + 2 H2O(l) → H3PO4(aq) + 2Cu(s) + H2SO4(aq)


(c) C6H5CHO(l) + 2[Ag (NH3)2]+(aq) + 3OH (aq) → C6H5COO(aq) + 2Ag(s) +4NH3 (aq) + 2 H2O(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?


In the above given reactions we can clearly see that:

(a) H3PO2(aq) + 4 AgNO3(aq) + 2 H2O(l) → H3PO4(aq) + 4Ag(s) + 4HNO3(aq)
Inference: Ag is getting reduced and P is getting oxidised.

(b) H3PO2(aq) + 2CuSO4(aq) + 2 H2O(l) → H3PO4(aq) + 2Cu(s) + H2SO4(aq)

Inference: Cu is getting reduced and P is oxidised.

(c) C6H5CHO(l) + 2[Ag (NH3)2]+(aq) + 3OH (aq) → C6H5COO(aq) + 2Ag(s) +4NH3 (aq) + 2 H2O(l)

Inference: Ag is getting reduced and C6H5CHO is getting oxidised.

(d) C6H5CHO(l) + 2Cu2+(aq) + 5OH(aq) → No change observed.

Inference: No reaction as Cu cannot oxidize C6H5CHO.

Hence, as a whole Ag+ and Cu2+ act as oxidising agents in reactions (a) and (b) respectively. In reaction (c), Ag+ oxidises C6H5CHO to  C6H5COO- , but in reaction (d), Cu2+ cannot oxidise C6H5CHO . Hence, we can say that Ag+ is a stronger oxidising agent than Cu2+.

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