Benzene c6h6 as a gas burns in air at 200 theoretical air

Question

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])

Substance	Formula	State	Δh-of(kJ/mole)
Oxygen	O2	g	0
Nitrogen	N2	g	0
Graphite	C	s	0
Diamond	C	s	1.88
Carbon dioxide	CO2	g	-393.5
Carbon monoxide	CO	g	-110.5
Hydrogen	H2	g	0
Water	H2O	g	-241.8
Water	H2O	l	-285.9
Chlorine	Cl2	g	0
Hydrogen chloride	HCI	g	-92.3
Hydrogen cyanide	HCN	g	+135.1
Methane	CH4	g	-74.9
Propane	C3H8	g	-103.8
n-Butane	C4H10	g	-124.7
n-Heptane	C7H16	g	-187.8
Benzene	C6H6	g	+82.9
Formaldehyde	CH2O	g	-115.9
Methanol	CH4O	g	-201.2
Methanol	CH4O	l	-238.6
Ethanol	C2H6O	L	-277.7
Ethylene	C2H4	g	52.5

^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.