Standard free energies of formation at 298 K are -237.2, -394.4 and -8.2 for H_2O(l), CO_2(g) and pentane (g) respectively. The value of E^_cell for t - Chemistry MCQ Chemistry | ExamTest.live | ExamTest.live

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Standard free energies of formation 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}^{\circ} for the pentane-oxygen fuel cell is:

A $0.0968 V$
B $1.968 V$
C $2.0968 V$
D $1.0968 V$

Solution & Step-by-step Explanation

Reaction: C_{5} H_{12} + 8 O_{2} \to 5 CO_{2} + 6 H_{2} O . Δ G^{\circ} = [5Δ G_{f}^{\circ} (CO_{2}) + 6Δ G_{f}^{\circ} (H_{2} O)] - [Δ G_{f}^{\circ} (Pentane) + 0] Δ G^{\circ} = [5 (- 394.4) + 6 (- 237.2)] - [- 8.2] Δ G^{\circ} = [- 1972 - 1423.2] + 8.2 = - 3395.2 + 8.2 = - 3387 kJ/mol .Number of electrons n = 32 (for C_{5} H_{12} \to 5 CO_{2}). E^{\circ} = \frac{- Δ G ^{\circ}}{n F} = \frac{3387 \times 1 0 ^{3}}{32 \times 96500} \approx 1.0968 V .

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Standard free energies of formation 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}^{\circ} for the pentane-oxygen fuel cell is:

A

0.0968 V

B

1.968 V

C

2.0968 V

D

1.0968 V

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Electrochemistry Fuel Cells Gibbs Free Energy

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