the heat of combustion of naphthalene at constant volume at 25 degree celsius was found to be -5133 kj/mole calculate the value of enthalpy change at constant pressure at the same temperature
The heat of combustion at constant volume is given to be -5133 KJ/mol.
Therefore, qv=-5133 kJ/mol.
The balanced equation of combustion of naphthalene is:
C10H8 + 12O2 -----> 10CO2 + 4H2O
Here, the number of gaseous moles on the products side= 10 (10 moles of CO2)
And, the number of gaseous moles on the reactants side= 12(12 moles of O2)
Hence, the change in number of gaseous moles, Δn = 10 - 12 = -2
The relation between qp and qv is:
qp = qv + ΔnRT
Substituting the values given,
qp = -5133*103 + (-2*8.314*298)
=> qp= -5137955.144 J/mol
Therefore, qv=-5133 kJ/mol.
The balanced equation of combustion of naphthalene is:
C10H8 + 12O2 -----> 10CO2 + 4H2O
Here, the number of gaseous moles on the products side= 10 (10 moles of CO2)
And, the number of gaseous moles on the reactants side= 12(12 moles of O2)
Hence, the change in number of gaseous moles, Δn = 10 - 12 = -2
The relation between qp and qv is:
qp = qv + ΔnRT
Substituting the values given,
qp = -5133*103 + (-2*8.314*298)
=> qp= -5137955.144 J/mol