Chapter 13, Problem 13.29P

Interpretation Introduction

Interpretation:

Whether an ionic compound that has a highly negative $\Delta {\text{H}}_{solution}$ in water is soluble or insoluble in water is to be determined. Also, it is to be explained in terms of enthalpy and entropy changes.

Concept introduction:

The enthalpy is the thermodynamic property of the system. It is defined as the sum of internal energy and the product of pressure and volume of the system. It is a state function and is independent of the path followed by the system from initial to the final state. It is an extensive property. The total enthalpy of the system cannot be measured directly so the change in enthalpy $\left(\Delta H\right)$ is measured. If $\Delta H$ of the reaction is positive, it is an endothermic reaction and if $\Delta H$ of the reaction is negative, it is an exothermic reaction.

The enthalpy change of solution is the enthalpy change when one mole of the ionic species is dissolved in water to give a solution of infinite dilution. It is represented by $\Delta H_{\text{solution}}$. It can either be positive or negative.

The entropy is the thermodynamic function that describes the randomness or disorderness of the system. It is represented by $S$. The direct measurement of entropy is not possible so its change is measured and is known as the entropy change $\left(\Delta S\right)$. It can be positive, negative or zero.