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here, please elaborate on how you did it, thanks! At room temperature, Hydrazine

ID: 827062 • Letter: H

Question

here, please elaborate on how you did it, thanks!

At room temperature, Hydrazine (N 2 H 4) is used as a precursor in the synthesis of rocket fuel. Calculate the change in enthalpy (Delta Hdegree =???) for the formation of Hydrazine from its elemental components using the following information: N 2 H 4 (1) + 0 2 (g) rightarrow N 2 (g) + 2H 2 0 (1) Delta Hdegree = -622.2 kJ H 2 (g) +1/2 0 2 (g) rightarrow H 2 0 (1) Delta Hdegree = -285.8 kJ N 2 (g) + 2 H 2 (g) - N 2H 4 (1) Delta Hdegree = ????????

Explanation / Answer


(1) N2H4 + O2 => N2 + 2 H2O, DH1 = -622.2 kJ

(2) H2 + 1/2 O2 => H2O, DH2 = -285.8 kJ


Reverse equation (1):

(3) N2 + 2 H2O => N2H4 + O2

DH3 = -DH1 = +622.2 kJ


Add equation (3) + 2 x equation (2):

N2 + 2 H2O + 2 H2 + O2 => N2H4 + O2 + 2 H2O


Cancel common terms to get required reaction:

N2 + 2 H2 => N2H4


Add up DH in the same way:

DH(rxn) = DH3 + 2 x DH2

= 622.2 + 2 x (-285.8)

= 50.6 kJ