Problem -

Benzene (C₆H₆) as a gas burns in air at 200% theoretical air. In answering the following parts, you may assume the products of combustion are CO₂, H₂O, O₂, and N₂. You may also assume the following:

Table 2.2 Heat of formation Δh^-o_f in kJ/mole (at 25°C and 1 atm)^a (abstracted from Reference [2])

^aValues for gaseous substances not in equilibrium at the standard state have been determined from liquid and the heat of vaporization.

a) For products and reactants at 25°C, calculate the heat of combustion of benzene in kJ/mol.

b) For the reactants at 25°C, compute the adiabatic flame temperature in Kelvin of benzene burning in air at 200% theoretical air.

c) For the reactants at 25°C, compute the adiabatic flame temperature in Kelvin of benzene burning in pure oxygen. Assume 200% of the required stoichiometric oxygen is supplied (molar basis). Is this a realistic temperature? Explain your answer.

d) Why is there a difference between b) and c) above? Give a physical argument.