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?