Consider the following enthalpy terms related to phase changes and solutions.

$H_{\text{v}\text{o}\text{o}},H_{\text{s}\text{u}\text{o}},H_{\text{i}\text{o}\text{t}},H_{\text{i}\text{r}\text{o}},H_{\text{i}\text{o}\text{n}}$

a$.$ Which term represents the change in enthalpy which is required to separate the molecules of a pure liquid?

b$.$ Which term represents the change in enthalpy upon dissolving a liquid into water?

c$.$ Which terms are ALWAYS negative $($exothermic$)?$

d$.$ Which terms are ALWAYS positive $($endothermic$)?$

$7.$ a$.$ For $C_6{H}_6(l),H_{\text{h}\text{i}\text{p}}=-31\mathrm{.}8kJ$ and $H_{\text{s}\text{o}\text{i}\text{n}}=2\mathrm{.}1kJ.$ What is $H_{\text{v}\text{e}\text{p}}$ in kJ$?$

b$.$ For $I_2(s),H_{\text{s}\text{u}\text{b}}=62\mathrm{.}42kJ$ and $H_{\text{i}\text{o}\text{i}\text{n}}=22\mathrm{.}6kJ.$ What is $H_{\text{i}\text{p}\text{d}}$ in kJ$?$

$8.$ Using enthalples of formation, calculate $H_{\text{v}\text{o}\text{p},}{H}_{\text{h}\text{i}\text{v}\text{d}}$ and $H_{\text{i}\text{o}\text{n}}($In kJ$)$ for hydrazine, $N_2{H}_4.($The native phase is liquid.$)$