Using Hess’s Law with the following data:

N2(g) + O2(g) = 2NO(g) Del(H) = 180.7kj
2NO(g) + O2(g) = 2NO2(g) Del(H)= -113.1kj
2N2O(g) = 2N2(g)+ O2(g) Del(H)=-163.2kj
Calculate Del(H) for the reaction:
N2O(g) + NO2(g) = 3NO(g)

To calculate ΔH for the reaction N2O(g) + NO2(g) = 3NO(g) using Hess's Law, you need to use the known reactions and systematically manipulate them to match the desired reaction.

Here's a step-by-step guide:

Step 1: Rearrange the given reactions
We need to manipulate the given reactions to obtain the desired reaction. To do this, we'll use algebraic operations to flip the reactions and multiply them in order to obtain the desired stoichiometry.

Given reaction 1:
N2(g) + O2(g) = 2NO(g) ΔH = 180.7 kJ

Given reaction 2:
2NO(g) + O2(g) = 2NO2(g) ΔH = -113.1 kJ

Given reaction 3:
2N2O(g) = 2N2(g) + O2(g) ΔH = -163.2 kJ

Step 2: Manipulate the given reactions
Since the goal is to obtain the reaction N2O(g) + NO2(g) = 3NO(g), we need to ensure that the coefficients of the reactants and products match.

Given reaction 1 can be used as it is.

Given reaction 2 needs to be multiplied by 2 to match the 2NO term on the left side.

Given reaction 3 needs to be multiplied by 3 and flipped to match the 3NO term on the right side.

After manipulation, the reactions become:

Reaction 1:
N2(g) + O2(g) = 2NO(g) ΔH = 180.7 kJ

Reaction 2:
4NO(g) + 2O2(g) = 4NO2(g) ΔH = -226.2 kJ

Reaction 3:
6N2O(g) = 6N2(g) + 3O2(g) ΔH = 489.6 kJ

Step 3: Combine the manipulated reactions
Now, add the manipulated reactions together to obtain the target reaction:

Added Reactions:
N2(g) + O2(g) = 2NO(g) ΔH = 180.7 kJ
+ 4NO(g) + 2O2(g) = 4NO2(g) ΔH = -226.2 kJ
+ 6N2O(g) = 6N2(g) + 3O2(g) ΔH = 489.6 kJ
------------------------------------------
N2(g) + 6N2O(g) + 8NO(g) + 3O2(g) = 4NO2(g) + 4NO(g)

Step 4: Calculate the ΔH for the target reaction
To find the ΔH for the target reaction, simply sum up the ΔH values of the added reactions:

ΔHtarget = ΣΔHadded reactions
ΔHtarget = 180.7 kJ + (-226.2 kJ) + 489.6 kJ

ΔHtarget = 444.1 kJ

Therefore, the ΔH for the reaction N2O(g) + NO2(g) = 3NO(g) is 444.1 kJ.

Add eqn 1 to 1/2 the reverse of eqn 2 + 1/2 eqn 3 to obtain the final equation you want. Then add the delta H values EXCEPT if you take 1/2 the equation also take 1/2 dH and if you reverse an equation then you change the sign of dH.