Standard free energies of formation (in kJ / mol ) at 298 ~K are -237.2,-394.4 and -8.2 for H_2 O(l), CO_2(~g) and pentane (g) respectively. The value of E_ cell ^ for the pentaneoxygen fuel cell is

Correct answer: D. 1.0968 ~V After calculation Δ G^ ^ , use the formula, Δ G^ ^ =-n F E^ ^ Here, n=32 is taken because balanced equation is C _ 5 H_ 12 +8 O _ 2 → 5 CO _ 2 +6 H _ 2 O

NEET 2008

Exam: NEET
Year: 2008
Subject: Chemistry
Chapter: Thermodynamics (C)

NEET 2008 · Chemistry · Thermodynamics (C)

Standard free energies of formation (in kJ / mol ) at 298 ~K are...

Standard free energies of formation (in

\mathrm{kJ} / \mathrm{mol}

) at

298 \mathrm{~K}

are

-237.2,-394.4

and -8.2 for

\mathrm{H}_2 \mathrm{O}(\mathrm{l}), \mathrm{CO}_2(\mathrm{~g})

and pentane

(\mathrm{g})

respectively. The value of

\mathrm{E}_{\text{cell }}^{\circ}

for the pentaneoxygen fuel cell is

Options

A $0.0968 \mathrm{~V}$
B $1.968 \mathrm{~V}$
C $2.0968 \mathrm{~V}$
D $1.0968 \mathrm{~V}$

Correct answer

D. $1.0968 \mathrm{~V}$

Step-by-step solution

After calculation

\Delta \mathrm{G}^{{}^{\circ}}

, use the formula,

\Delta \mathrm{G}^{{}^{\circ}}=-n F E^{{}^{\circ}}

Here,

n=32

is taken because balanced equation is

\mathrm{C}}_{5} \mathrm{H}_{12}+8 \mathrm{O}

}_{2} → 5

\mathrm{CO}}_{2}+6 \mathrm{H}

}_{2}

\mathrm{O}

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