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The bond dissociation energy depends upo...

The bond dissociation energy depends upon the nature of the bond and nature of the molecule. If any molecule more than 1 bonds of similar nature are present then the bond energy reported is the average bond energy.
Determine `C-C and C-H` bond enthalpy (in kJ/mol). Given: `Delta_(f)H^(0) (C_(2)H_(6),g)= -85kJ//mol, Delta_(f) H^(0) (C_(3)H_(8), g)= -104kJ//mole, Delta_("sub")H^(0) (C,s)= 718kJ//mol`, B.E. (H-H)= 436 kJ/mol,

A

414345

B

345414

C

`287404.5`

D

None of these

Text Solution

Verified by Experts

The correct Answer is:
B
`2 C(s)+3H_(2)(g)rarrC_(2)H_(6)(g)`
`Delta_(f)H^(@)=[(2xxDelta_("sub")H(C,s)),(3xxB.E.(H-H))]`
`-[(B.E.(C-C)),(+6xxB.E.(C-H))]`
`-85 = 2xx718 + 3 xx 436 - (x+6y)`
`x + 6y = 2829" ...(1)"`
Similarly, for `C_(3)H_(8)(g)`
`2x+8y= 4002 " ...(2)"`
from Eqs. (1) and (2)
x = 345 kJ/mol, y = 414 kJ/mol
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