Chapter 8, Problem 8.84SP

Interpretation Introduction

Interpretation:

$\Delta H_f^{°}$ for 2-Methylpropene has to be calculated.

Concept Introduction:

• Standard heat of formation

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 and change in enthalpy

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,

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