Bond energy of c-h is-
Given that the heat of formation of ch4 , heat of sublimation of carbon and heat of dissociation of H2 are -74.8 ,+719.6 and 435.4 kj/mol respectively
a.1665.2kj. b.416.3kj
c.816.3kj. d.614.2kj
Consider the equation,
CH4(g) → C(g) + 4H(g)
Data equations:
C(s) + 2H2(g) → CH4(g) ………………………………… ∆H = -74.8 kJ mol-1
C(s) →C(g) …………………………………………………… ∆H = + 719.6 KJ mol-1
H2(g) → 2H(g) ………………………………………………… ∆H = + 435.4 KJ mol-1
Reverse equation 1 CH4(g) → C(s) + 2H2(g) ……………………………………. ∆H = +74.8 kJ mol-1
equation 2 C(s) →C(g) ………………………………………………………… ∆H = + 719.6 KJ mol-1
Multiply by 2 to equation 3 2H2(g) → 4H(g) ………………………………………………… ∆H = 2(+435.4) KJ mol-1
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After adding we get CH4(g) → C(g) + 4H2(g)………………………………… ∆H = +1665.2 KJ mol-1
No. of C-H bonds are 4
Therefore, one C-H = total / 4 = 1665.2/4= 416.3 KJ mol-1
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