CHEMISTRY

Please explain.

The enthalpy changes for two different hydrogenation reactions of C2H2 are:

C2H2+H2---->C2H4 Delta H 1

C2H2+2H2---->C2H6 Delta H 2

Which expression represents the enthalpy change for the reaction below?

C2H4+H2---->C2H6 Delta H = ?

A. Delta H 1 + Delta H 2
B. Delta H 1 - Delta H 2
C. Delta H 2 - Delta H 1
D. -Delta H 1- Delta H 2

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  1. Reverse H1 (make - dH) and add to H2.

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