Q.

The mass of silver (Molar mass of Ag: 108 g mol-1) displaced by a quantity of electricity which displaces 5600 mL of O2 at S.T.P. will be ______ g.       [2024]


Ans.

(108)

                Number of moles of oxygen at STP

                 (nO2)=Volume at STP in mL22400=560022400=0.25 mol

                 Oxidation of water to oxygen is represented as:

                 2H2O→O2+4H++4e-

                  By stoichiometry: ne-4=nO21,  ne-4=0.251,ne-=1 mol

                  Reduction of silver to deposit silver metal is represented as:

                  Ag++e-→Ag

                  By stoichiometry: nAg1=ne-1,  nAg=1 mol

                  Mass of silver deposited =nAg×MAg=1 mol×108 g mol-1=108 g