Question

calculate the internal energy of enthalpy of any random system.also find out the mathematical relation between internal energy enthalpy and then entropy?

Answer 1

$U=\frac{m}{M}C_VT$

For air $M=28.96 \cdot 10^{-3}kg/mol$ and $C_V=\frac{i}{2}R=\frac{5}{2}\cdot 8.31\approx20.8\frac {J}{mol\cdot K}$

$U=\frac{m}{M}C_VT=\frac{1}{28.96 \cdot 10^{-3}}\cdot 20.8\cdot 293=210442J$

The enthalpy of air

$H=U+pV=210442+2\cdot 10^6\cdot 0.05=310442J$

Enthalpy is the sum total of all the energies, whereas entropy is the measure of the change in enthalpy/temperature.