Chapter 8, Problem 8.79SP

Interpretation Introduction

Interpretation:

$\Delta H_f^{°}$ for benzene has to be calculated from the data of  given reaction.

Concept Introduction:

Standard heat of formation of a compound is termed as quantity of heat absorbed or evolved at $25°C$ temperature and $1atm$ pressure when one mole of a compound is formed form its constituent elements in pure form under the same reaction conditions at $25°C$ temperature and $1atm$ pressure.

Enthalpy corresponds to heat content of the system and it 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.  Change in enthalpy in a reaction and heat of formation are related by the formula,

$\Delta H_{rxn}^{°}=\Sigma \Delta H_f^{°}(product)-\Sigma \Delta H_f^{°}(reac\tan t)$

Where,

$\begin{array}{l}\Delta H_{rxn}^{°}=\text{ enthalpy change in reaction}\\ \Delta H_f^{°}(product)=\text{ enthalpy or heat of formation of product}\\ \Delta H_f^{°}(reac\tan t)=\text{ enthalpy or heat of formation of }reac\tan t\end{array}$