Enthelpy of the decomposition reaction of N2H4 gas

Thread starter lizgore94
Start date Jan 28, 2013
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Decomposition Gas Reaction

AI Thread Summary

The discussion focuses on calculating the change of heat for the reaction of hydrazine (N2H4) decomposing into nitrogen (N2) and hydrogen (H2). The user initially calculated the change in heat as -692 but expected the correct answer to be -86.0. The confusion arises from the source of the numerical values used in the calculation. The values mentioned include bond energies: 163 kJ/mol for the N-H bond, 436 kJ/mol for the H-H bond, and 391 kJ/mol for the N-N bond. Clarification is sought on how to accurately apply these bond energies to arrive at the correct enthalpy change for the reaction.

Jan 28, 2013

lizgore94

I am trying to determine the change of heat for:

N2H4(g) -> N2(g) + 2H2(g)

Here is what I did and what I got the correct answer is -86.0 which I am clearly not getting

[(163)+ (2*436)] - [(4*391) + (163)] = -692

thanks for any help!

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Jan 28, 2013

sjb-2812

Where have all these numbers come from?

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