Chapter 8, Problem 8.55SP

Interpretation Introduction

Interpretation:

The sign of $\Delta H$ for an exothermic reaction and endothermic reaction has to be described.

Concept Introduction:

The heat content of the system is termed as enthalpy and it is represented by ‘H’. It is the sum of internal energy ‘E’ and product of volume and pressure,

$H=E+PV$

$\Delta H$ refers to change in enthalpy.  Since enthalpy corresponds to the heat content of the system, change in enthalpy $\Delta H$ corresponds to change in heat content of the system at constant pressure and hence it is equivalent to $q_p.$  Thus,

$\Delta H=q_p$

Exothermic reaction is a reaction during which heat energy is released.

Endothermic reaction is a reaction during which heat energy is absorbed.