# How do you use Hess's Law to calculate enthalpy for this reaction?

##
Given Data:

#"N"_2(g) + "O"_2(g) -> 2"NO"(g)#

#DeltaH = +"180.7 kJ"#

#2"NO"(g) + "O"_2(g) -> 2"NO"_2(g)#

#DeltaH = -"113.1 kJ"#

#2"N"_2"O"(g) -> 2"N"_2(g) + "O"_2(g)#

#DeltaH = -"163.2 kJ"#

Use Hess' Law to calculate #DeltaH# for the reaction:

#"N"_2"O"(g) + "NO"_2(g) -> 3"NO"(g)#

Given Data:

#DeltaH = +"180.7 kJ"#

#DeltaH = -"113.1 kJ"#

#DeltaH = -"163.2 kJ"#

Use Hess' Law to calculate

##### 1 Answer

#### Explanation:

PC of cake

Adding the 3 equations:

Adding one more reaction

Adding previous 2 equations and dividing by 2

Finally,

The Enthalpy is the sum of the all reactions: