[stripitred]

Hello;
I'm having a bit of trouble with the resolution of this exercise, any kind of help would be extremely helpful!

I have to determine the enthalpy of formation of this equation:

2NO₂ + O₂ ----- 2N₂O

With only this data:

a) 2NH3 + 3N2O --- 4N2 + 3H2O      =  ∆H° -1010 KJ
b) 4NH3 + 3O2 ---- 2N2 + 6H2O       = ∆H° -1531 KJ

[Aeon]

2NO₂ + O₂ ----- 2N₂O

can, by Hess's law, be expressed as a linear combination of reactions a) and b).

By linear combination, I mean an equation of the form:

c₁A + c₂B = C

where c₁ and c₂ are constants.

[SABRY]

1. Heat of formation of element is zero

2. Manipulate equation (a) and (b) such that NH3 and H2O are eliminated

3. For example, multiply equation (a) by 2 then subtract equation (b), what will you get?