Chemistry - Thermodynamics - II Question with Solution | TestHub

Enthalpy, in a thermodynamic system, is the measure of its energy which is equal to the sum of the internal energy and the product of its pressure and volume.

 $\mathrm{H} = \mathrm{U}+\mathrm{PV}$ (By definition)

$$\begin{gathered} \mathrm{\Delta H}=\mathrm{\Delta U}+\mathrm{\Delta }\left(\mathrm{PV}\right) \\ \mathrm{or} \mathrm{\Delta H}=\mathrm{\Delta U}+\mathrm{V\Delta P}+ \mathrm{P\Delta V} \end{gathered}$$

 at constant pressure

$\mathrm{\Delta H}=\mathrm{\Delta U}+\mathrm{P\Delta V}$ So, option A is incorrect.

$\mathrm{\Delta U}=\mathrm{q}+\mathrm{W}$ First law of thermodynamics.

${\mathrm{\Delta S}}_{\mathrm{sys}}+{\mathrm{\Delta S}}_{\mathrm{surr}}\ge 0 \mathrm{or} {\mathrm{\Delta S}}_{\mathrm{Universe}} \ge 0$  A form of second law of thermodynamics.

$\mathrm{\Delta G}=\mathrm{\Delta H}-\mathrm{T\Delta S}$ Second law of thermodynamics.