- #1

- 8

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C

_{2}H

_{2}+ 2H

_{2}-------> C

_{2}H

_{6}

Assume the following mean bond energies

C[itex]\equiv[/itex]C = 813 KJ mole

^{-1}

C - C = 364 KJ mole

^{-1}

C - H = 413 KJ mole

^{-1}

H - H = 436 KJ mole

^{-1}

Attempted Solution:

Bonds broken

1 C[itex]\equiv[/itex]C = 813 KJ mole

^{-1}( 813 KJ mole

^{-1})

2 H - H = 436 KJ mole

^{-1}(2 x 436 KJ mole

^{-1})

Bonds formed

4 C - H = 413 KJ mole

^{-1}(4x 413 KJ mole

^{-1})

1 C - C = 364 KJ mole

^{-1}(364 KJ mole

^{-1})

ΔH

_{h}- Enthalpy of hydrogenation

ΔH

_{h}= ((813 + 2x 436) - ((4x 413) + 364)) KJ mole

^{-1}

ΔH

_{h}= 1685 KJ mole

^{-1}- 2016 KJ mole

^{-1}

ΔH

_{h}= -331 KJ mole

^{-1}

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Is my method and the way I worked it out correct ?