In a fuel cell methanol is used as fuel and oxygen gas is used as an oxidizer. The reaction is CH_(3)OH(l)+3/2 O_(2)(g) rarr CO_(2)(g)+2H_(2)O(l) at 298 K standard Gibb's energies of formation for CH_(3)OH(l), H_(2)O(l) and CO_(2)(g) are -166.2, -237.2 and -394.4" kJ mol"^(-1) respectively. If standard enthalpy of combustion of methanol is -726" kJ mol"^(-1), efficiency of the fuel cell will be -

In a fuel cell methanol is used as fuel and oxygen gas is used as an o

1.	In a fuel cell methanol is used as fuel and oxygen gas is used as an oxidizer. The reaction is CH_(3)OH(l)+3/2 O_(2)(g) rarr CO_(2)(g)+2H_(2)O(l) at 298 K standard Gibb's energies of formation for CH_(3)OH(l), H_(2)O(l) and CO_(2)(g) are -166.2, -237.2 and -394.4" kJ mol"^(-1) respectively. If standard enthalpy of combustion of methanol is -726" kJ mol"^(-1), efficiency of the fuel cell will be -
Answer» `87 %` `90 %` `97 %` `80 %` Solution :`CH_(3)OH(l)+3/2 O_(2) (g) rarr CO_(2)(g)+2H_(2)O(l)` `DeltaG^(@)=DeltaG_(P)^(@)-DeltaG_(R)^(@)` `DeltaG^(@)=[DeltaG_(CO_(2))^(@)+2DeltaG_(H_(2)O)^(@)]-[DeltaG_(CH_(3)OH)^(@)+3/2 DeltaG_(O_(2))^(@)]` `-394.4+2xx(-237.2)-[166.2]` `-868.8-166.2` `G_(1)G^(@)=-702.6" KJ/mol"` EFFICENCY `=(DeltaG^(@))/(DeltaH^(@))xx100=(-702.6 kJ)/(-726 kJ)xx100=96.77%` `[DeltaG_("USEFUL WORK")=DeltaH_("total energy")-TDeltaS_("useless work")]`