Chapter 3, Problem 3B.7ST

Interpretation Introduction

Interpretation:

The entropy it generates in water at ${15}^{\circ }C$ has to be calculated.

Concept Information:

Entropy changes in surroundings:

Using the value for the change in enthalpy in a system and the temperature, we can calculate $\text{ΔS}$ for reaction of isolated system.

${\text{ΔS}}_{\text{surr}}\text{=}\frac{{\text{q}}_{\text{surr,}}{}_{\text{rev}}}{\text{T}}$

However, the surroundings are so extensive and so remain at constant pressure regardless of any events taking place in the system. Hence, the heat transferred into the system can be identified with change in their enthalpy; ${\text{q}}_{\text{surr,}}{}_{\text{rev}}\text{=}{\text{ΔH}}_{\text{surr}}$.

The enthalpy is a state function, its value is independent of the path and the same value of ${\text{ΔH}}_{\text{surr}}$ is obtained regardless about the heat transferred. Hence, the label ‘rev’ is removed and obtained as,

$\Delta S_{surr}=\frac{q_{surr}}{T}$