# Enthalpy =

(a) $T^2 [\frac{\delta(G/T)}{\delta T}]_P$
(b) $-T^2 [\frac{\delta(G/T)}{\delta T}]_P$
(c) $T^2 [\frac{\delta(G/T)}{\delta T}]_V$
(d) $-T^2 [\frac{\delta(G/T)}{\delta T}]_V$

Answer: $-T^2 [\frac{\delta(G/T)}{\delta T}]_P$
It can be derived from the definition of Entropy and Gibbs free energy, that, $[\frac{\delta(G/T)}{\delta T}]_P = - \frac{\Delta H}{T_2}$
$\Longrightarrow \Delta H =-T^2 [\frac{\delta(G/T)}{\delta T}]_P$
This is one of the forms of Gibbs-Hemholtz equation.
answered Feb 27, 2014

Enthalpy is a measurement of energy in a thermodynamic system. It is equal to the internal energy of the system plus the product of pressure and volume
Enthalpy = $-T^2 [\frac{\delta(G/T)}{\delta T}]_P$