How do you: Calculate deltaH for the reaction 2C + H2 → C2H2?

Question

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Given the following data:


C2H2 + 2.5O2 → 2CO2 + H2O DH = −1300 kJ


C + O2 → CO2 DH = −394 kJ


H2 + 0.5O2 → H2O DH = −286 kJ




Calculate DH for the reaction


2C + H2 → C2H2



Please answer and explain thank you!

Answer 1

It's kind of like Algebra

the DH for 2C + H2 ->C2H2 simply equals the heat of formation of C2H2. DH=H of formation(HofF) of C2H2 - 2* HofF of C - HofF of H2. Since HofF of C and H are zero (HofF of an element is always zero) then the DH= HofF of C2H2

-1300=2*CO2 + H2O - C2H2
-394 = CO2
-286 = H2O

-1300 = 2* -394 + -286 - C2H2
C2H2=-226