Enthalpy Practice Test

Consider the following processes:

1. $A \rightarrow 2B + C + \Delta $H_{1}$$

2. $D\rightarrow B + C + \Delta $H_{2}$$

3. $D \rightarrow 2E + \Delta $H_{3}$$

Which for the following expresses for the process $A + C \rightarrow 4E$ ?

The formation of nitrous oxide is a 2-step process.

$$N_{2}$ + $O_{2}$ \rightarrow 2NO (step 1)$

$2NO + $O_{2}$ \rightarrow $2NO_{2}$ (step 2)$

$$N_{2}$ + $2O_{2}$ \rightarrow $2NO_{2}$ (overall reaction)$

The overall enthalpy of the reaction is +68kJ.

If the enthalpy change of step 1 is 180kJ, what is the enthalpy change of step 2?