Calc Enthalpy of Formation N2O5(g) from Data

[chemister]

How would you calculate the standard enthalpy of formation of N2O5(g) in kJ/mol from the following data (all species are gases):
2 NO + O2-----2 NO2 ∆H° = –114.1 kJ
4 NO2 + O2-----2 N2O5 ∆H° = –110.2 kJ
N2 + O2------2 NO ∆H° = +180.5 kJ

Any help is greatly appreciated!

 

[DH]

How would you calculate the standard enthalpy of formation of N2O5(g) in kJ/mol from the following data (all species are gases):
2 NO + O2-----2 NO2 ∆H° = –114.1 kJ
4 NO2 + O2-----2 N2O5 ∆H° = –110.2 kJ
N2 + O2------2 NO ∆H° = +180.5 kJ

Any help is greatly appreciated!

ok, here is your answer. this one is the easy one!
time first and third one with 2, then add three of them up, we have:
4 NO + 2O2 + 4NO2 + O2 + 2N2 + 2O2 -> 4NO2 +2N2O5 + 4NO

5O2 + 2N2 -> 2N2O5 ∆H° = 2*(-114.1) -110.2 + 2*180.5 = 22.6
-> standard enthalpy of formation of N2O5 = 22.6/2 = 11.3 kJ

 

[kashmiri]

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[kashmiri]

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