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The heat of hydrogenation for 3-methylbu...

The heat of hydrogenation for 3-methylbutene and 2-pentene are -30 kcal/mol and -28 kcal/mol respectively. The heats of combustion of 2-methylbutane and pentane are - 784 kcal/mol and -782 kcal/mol respectively. All the values are given under standard conditions. Taking into account that combustion of both alkanes give the same products, what is `DeltaH` (in kcal/mol) for the following reaction under same conditions ?

A

0

B

`-4`

C

`-2`

D

2

Text Solution

Verified by Experts

The correct Answer is:
B

`DeltaH_(1) =-30 kcal//"mol", DeltaH_2 =(-784+782) kcal//"mol", DeltaH3 = 28 kcal//"mol"`
`implies DeltaH_(1) +DeltaH_(2) + DeltaH_(3) = -4` kcal/mol
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