91影视

As Enthalpy means 鈥渉eat鈥� so enthalpy of the heat of vaporization can be defined as the heat which is a form of energy required to change the liquid phase into the vapour phase.

$\mathbf{Log}\frac{P1}{P2}\mathbf{=}\frac{\mathbf{-}{{\mathbf{螖贬}}^o}_{\mathrm{vap}}}{\mathbf{2}\mathbf{.}\mathbf{303}\mathbf{脳}\mathbf{R}}\mathbf{(}\frac{\mathbf{1}}{\mathbf{T}\mathbf{1}}\mathbf{-}\frac{\mathbf{1}}{\mathbf{T}\mathbf{2}}\mathbf{)}$

Where

${\mathrm{P}}_1$= Vapour pressure at temperature${\mathrm{T}}_1$

${\mathrm{P}}_2$= Vapour pressure at temperature${\mathrm{T}}_2$

R = Gas constant at the universal level.

The relationship between pressure and temperature is directly proportional, if the temperature increases the pressure also increases and vice-versa.

Temperature,${\mathbf{T}}_1\mathbf{=}\mathbf{-}{\mathbf{164}}^o\mathbf{C}\mathbf{=}\mathbf{109}\mathbf{k}$

Vapour pressure at temperature,${\mathbf{P}}_{\mathbf{1}}\mathbf{=}\mathbf{1}\mathbf{atm}$

Temperature,${\mathbf{T}}_2\mathbf{=}{\mathbf{100}}^o\mathbf{C}\mathbf{=}\mathbf{173}\mathbf{k}$

Let vapour pressure at temperature,${\mathbf{P}}_2\mathbf{=}\mathbf{42}\mathbf{.}\mathbf{8}\mathbf{atm}$

Universal gas constant, $(\mathbf{R}\mathbf{=}\mathbf{8}\mathbf{.}\mathbf{314}\mathbf{J}\mathbf{/}\mathbf{mole}\mathbf{/}\mathbf{k})$.

Enthalpy of vaporization,${{\mathbf{螖贬}}^o}_{\mathrm{vap}}$=?

Put the values in the above equation of enthalpy of vaporization:

role="math" localid="1658850210476" $\begin{array}{c}\mathbf{Log}\left(\frac{P1}{P2}\right)\mathbf{=}\frac{\mathbf{-}{{\mathbf{螖贬}}^o}_{\mathrm{vap}}}{\mathbf{2}\mathbf{.}\mathbf{303}\mathbf{脳}\mathbf{R}}\mathbf{(}\frac{\mathbf{1}}{\mathbf{T}\mathbf{1}}\mathbf{-}\frac{\mathbf{1}}{\mathbf{T}\mathbf{2}}\mathbf{)}\\ \mathbf{Log}\mathbf{\left(}\frac{\mathbf{1}}{\mathbf{42}\mathbf{.}\mathbf{8}}\mathbf{\right)}\mathbf{=}\frac{\mathbf{-}{{\mathbf{螖贬}}^o}_{\mathrm{vap}}}{\mathbf{2}\mathbf{.}\mathbf{303}\mathbf{脳}\mathbf{8}\mathbf{.}\mathbf{314}\mathbf{J}\mathbf{/}\mathbf{mole}\mathbf{/}\mathbf{k}}\mathbf{(}\frac{\mathbf{1}}{\mathbf{109}}\mathbf{-}\frac{\mathbf{1}}{\mathbf{173}}\mathbf{)}\\ \mathbf{Log}\left(\mathbf{1}\right)\mathbf{-}\mathbf{Log}(\mathbf{42}\mathbf{.}\mathbf{8})\mathbf{=}\frac{\mathbf{-}{{\mathbf{螖贬}}^o}_{\mathrm{vap}}}{\mathbf{2}\mathbf{.}\mathbf{303}\mathbf{脳}\mathbf{8}\mathbf{.}\mathbf{314}\mathbf{J}\mathbf{/}\mathbf{mole}\mathbf{/}\mathbf{k}}\mathbf{\left(}\frac{\mathbf{173}\mathbf{-}\mathbf{109}}{\mathbf{173}\mathbf{脳}\mathbf{173}}\mathbf{\right)}\\ \mathbf{0}\mathbf{-}\mathbf{1}\mathbf{.}\mathbf{63}\mathbf{=}\frac{\mathbf{-}{{\mathbf{螖贬}}^o}_{\mathrm{vap}}}{\mathbf{2}\mathbf{.}\mathbf{303}\mathbf{脳}\mathbf{8}\mathbf{.}\mathbf{314}\mathbf{J}\mathbf{/}\mathbf{mole}\mathbf{/}\mathbf{k}}\left(\frac{64}{18857}\right)\end{array}$

role="math" localid="1658850256474" $\begin{array}{c}\mathbf{-}\mathbf{1}\mathbf{.}\mathbf{63}\mathbf{=}\frac{\mathbf{-}{{\mathbf{螖贬}}^o}_{\mathrm{vap}}}{\mathbf{2}\mathbf{.}\mathbf{303}\mathbf{脳}\mathbf{8}\mathbf{.}\mathbf{314}\mathbf{J}\mathbf{/}\mathbf{mole}\mathbf{/}\mathbf{k}}\mathbf{\left(}\frac{\mathbf{64}}{\mathbf{132032}\mathbf{.}\mathbf{5}}\mathbf{\right)}\\ {{\mathbf{螖贬}}^o}_{\mathrm{vap}}\mathbf{=}\frac{\mathbf{1}\mathbf{.}\mathbf{63}\mathbf{脳}\mathbf{2}\mathbf{.}\mathbf{303}\mathbf{脳}\mathbf{8}\mathbf{.}\mathbf{314}\mathbf{脳}\mathbf{18857}}{64}\\ {{\mathbf{螖贬}}^o}_{\mathrm{vap}}\mathbf{=}\mathbf{9195}\mathbf{.}\mathbf{69}\mathbf{Joule}\mathbf{/}\mathbf{mole}\\ {{\mathbf{螖贬}}^o}_{\mathrm{vap}}\mathbf{=}\mathbf{9}\mathbf{.}\mathbf{195}\mathbf{KJ}\mathbf{/}\mathbf{mole}\end{array}$

The enthalpy of the vaporization of the liquid${{\mathbf{螖贬}}^o}_{\mathrm{vap}}$ at temperature $\mathbf{-}\mathbf{100}\mathbf{掳}\mathbf{C}$ is 9.195kJ/mole.