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In a fuel celll, methanol is used as a f...

In a fuel celll, methanol is used as a fuel and `O_(2)` is used as oxidizer. The standard enthalpy of combustion of methanol is -726 kJ `mol^(-1)`. The standard free energies of formation of `CH_(3)OH(I), CO_(2)(g) and H_(2)O(I)` are -166.3, -394.4 and -237.1 kJ `mol^(-1)` respectively.
The standard free energy change of the reaction will be

A

`-597.8 kJ mol^(-1)`

B

`-298 kJmol^(-1)`

C

`- 465.2 kJ mol^(-1)`

D

`-702.3kJ mol^(-1)`

Text Solution

Verified by Experts

The correct Answer is:
d
The reaction is
`CH_(3)OH(l) + (3)/(2) O_(2)(g) rarr CO_(2)(g) + 2H_(2)O(l) `
`Delta_(r)G^(@) = SigmaDelta_(f)G^(@)(` Products) - `SigmaDelta_(f)G^(@)(`Reactants)
`= [ Delta_(f)G^(@) ( CO_(2) +2Delta_(f) G^(@) (H_(2)O)] -[Delta_(f)G^(@) (CH_(3)OH)+(3)/(2)Delta_(f)G^(@) (O_(2))]`
`= [( - 394.4) + 2 ( - 237.1) ] - [ - 166.3 + (3)/(2) (0)]`
`=- 702 . 3 kJ mol^(-1)`
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Knowledge Check

  • In a fuel cell (device used for producing electricity directly from a chemical reaction )methanol is used as a fuel and oxygen gas is used asan oxidizer. The standard enthalpy of combustion of methanol is -721kJ mol^(-1) . The standard free energiesof formation of CH_(3)OH(l, CO_(2)(g) and H_(2)O(l) are- 166.3 , -394.4 and - 237 .1 kJ mol^(-1) respectively. The standard internal energy change of the cell reaction will be

    A
    `-727.24 kJ mol^(-1)`
    B
    `-724.76kJ mol^(-1)`
    C
    `-728.48 kJ mol^(-1)`
    D
    `- 723. 42 kJ mol^(-1)`

  • In a fuel cell (device used for producing electricity directly from a chemical reaction )methanol is used as a fuel and oxygen gas is used asan oxidizer. The standard enthalpy of combustion of methanol is -721kJ mol^(-1) . The standard free energiesof formation of CH_(3)OH(l, CO_(2)(g) and H_(2)O(l) are- 166.3 , -394.4 and - 237 .1 kJ mol^(-1) respectively. The standard entropy change accopanying the cell reaction willbe

    A
    `+ 24.11 JK^(-1)`
    B
    `-24.1JK^(-1)mol^(-1)`
    C
    `+19.1JK^(-1) mol^(-10`
    D
    `-19.1 JK^(-1) mol^(-1)`

  • In a fuel cell (device used for producing electricity directly from a chemical reaction )methanol is used as a fuel and oxygen gas is used asan oxidizer. The standard enthalpy of combustion of methanol is -721kJ mol^(-1) . The standard free energiesof formation of CH_(3)OH(l, CO_(2)(g) and H_(2)O(l) are- 166.3 , -394.4 and - 237 .1 kJ mol^(-1) respectively. The efficiency of the fuel cell will be

    A
    `96.7 %`
    B
    `66.2%`
    C
    `41.3%`
    D
    `85.1%`