Chapter 8, Problem 8.34CP

Interpretation Introduction

Interpretation:

The signs of $\Delta H,\Delta S,\Delta G$ have to be explained.

Concept Introduction:

• Entropy refers to measurement of randomness or disorderliness in the system.  More the number of molecules in a system more will be the movement of molecules and greater will be the entropy given that weak intermolecular forces prevails between molecules.
• Entropy is denoted by ‘S’ and $\Delta S°$ refers to change in entropy of the system.  $\Delta S°$ value positive for a phenomenon indicates the process is spontaneous which proceeds without any external influence.  $\Delta S°$ value negative for a phenomenon indicates the process is non–spontaneous which proceeds upon some external influence.
• The heat content of the system is represented by ‘H’ and it is the sum of internal energy ‘E’ and product of volume and pressure,

$H=E+PV$

•  $\Delta H$ refers to change in enthalpy of the system,

$\Delta H=\Delta E+P\Delta V$

• The term free energy G, refers to energy available in the system to do work and enthalpy H, refers to heat content of the system.
• Spontaneous process has positive entropy value and negative free energy, enthalpy value.
• Non-spontaneous process tends to proceed with negative entropy value and positive free energy and enthalpy.