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QAIPMT-2008-Ch-2225: NEET 2008 Chemistry - Class 12 AIPMT-2008-Ch-2225 Solution: Standard free energies of formation (in kJ/mol) at 298 K are…
Standard free energies of formation (in kJ/mol) at 298 K are -237.2, -394.4 and -8.2 for , and pentane (g) respectively. The value of for the pentane-oxygen fuel cell is
Multiple Choice Options
- A 1.0968 V
- B 0.0968 V
- C 1.968 V
- D 2.0968 V
Step-by-Step Verified Solution
At Anode:
C 5 H 12 + 10H 2 O _ 5CO 2 + 32H + + 32e -
At Cathode:
8O 2 + 32H + + 32e - _ 16H 2 O
-------------------------------------------------
C 5 H 12 (g)
+ 8O 2 (g) _ 5CO 2 (g)
+ 6H 2 O(l)
_ G = 5_ _ G CO 2
+ 6 _ G (H 2 O) � [ _ G (C 5 H 12 )
+8 _ _ G O 2
]
= 5 _ (� 394.4) + 6 _ (�237.2) � (� 8.2 + 0)
= � 3387 kJ mol �1
= � 3387 _ 10 3 J mol �1
_ G = - nFE o cell
From the overall equation we find n = 32
� 3387 _ 10 3 = -32 _ 96500 _ E o cell
E o cell = _ 3387 _ 10 3 _ 32 _ 96500 = 1.0968 V