Answer to Question #89717 in Molecular Physics | Thermodynamics for Shivam Nishad

Question

What is entropy ? Calculate the change in entropy of an ideal gas for an isothermal expansion.

Answer 1

entropy is an extensive property of a thermodynamic system: the entropy S is the natural logarithm of the number of microstates, multiplied by the Boltzmann constant k_B.

the change in entropy of an ideal gas for an isothermal expansion:

$$S = \int \frac{\delta Q}{T} = \frac{1}{T} \int \delta Q = \frac{Q}{T}$$

where T is temperature of an idela gas, Q is the heat absorbed during the isothermal expansion