Question

Study the reactions.

Answer 1

Answer:

B) by first reversing Reaction 2 and then adding the enthalpy of Reaction 1 and the enthalpy of Reaction 2

Explanation:

C2H2 (g)+2H2 (g)→C2H6 (g)   ΔH=−75 kcal

C2H4 (g)+H2 (g)→C2H6 (g)     ΔH=−33 kcal

C2H2 (g)+H2 (g)→C2H4 (g)     ΔH= ?

First step - Reverse reaction 2.

C2H6 (g)  → C2H4 (g) + H2 (g)    ΔH= 33 kcal

Second step - Add reaction 1 and the reversed reaction 2. This gives us:

C2H2 (g) + 2H2 (g)  +  C2H6 (g) → C2H6 (g) + C2H4 (g) + H2 (g)

Simplifying gives:

C2H2 (g)+H2 (g)→C2H4 (g)

The correct option is:

B) by first reversing Reaction 2 and then adding the enthalpy of Reaction 1 and the enthalpy of Reaction 2