Standard change of enthelpy, hess's law question

AI Thread Summary
The discussion revolves around a homework problem involving Hess's Law and the standard change of enthalpy. The user attempted to manipulate the reaction equations by multiplying the hydrogen and oxygen reaction by three and combining it with another equation involving hydrazine and ammonia. They successfully matched water and oxygen but are struggling to align the nitrogen components. The user seeks guidance on whether to divide the equations by four to achieve the necessary balance. Assistance is requested to clarify the manipulation of the equations for proper alignment.
gurpalc
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Homework Statement



http://imgur.com/lb0HL

Homework Equations



in pic

The Attempt at a Solution



So I multiplied the H2 + 1/2O2 equation by 3 and added it to the (N2H4, 2NH3) equation.

I got H2O to match up and O2 to match up, but I don't know how to manipulate the other

equations to get 4N2 to match up. Do I divide all by four? I don't know.
Please help.
Thanks
 
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