1.

(a) Calculate DeltaG^(@) for the reaction Zn(s) +Cu^(2+) (aq) to Zn^(2+)(aq)+Cu(s) Given : E^(@)" for "Zn^(2+)//Zn= -0.76V and E^(@)" for " Cu^(2+)//Cu=+0.34V R=8.314JK^(-1)"mol"^(-1) F=96500"C mol"^(-1). (b) Give two advantages of fuel cells.

Answer»

Solution :(a) `E_("cell")^(@)=E_(Cu^(+)//Cu)^(@)-E_(Zn^(2+)//Zn)^(@)`
`=0.34-(-0.76)=1.1V`
`DeltaG^(@)=-nFE_("cell")^(@)`
Substituting the values, we have
`DeltaG^(@)= -2xx96500"C mol"^(-1)xx1.1V`
`=-212300"J mol"^(-1)`
`=-212.3"kJ mol"^(-1)`
(b) Advantages of fuel cell
(i) Fuel cells PRODUCE electricity with an efficiency of `70%` compared to thermal PLANTS where the efficiency is `40%`.
(ii) Fuel cells are pollution free as the only product formed is water.


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