Question

How do I calculate enthalpy of vaporization of benzene at vaporization temperature knowing heat capacity of liquid and gaseous benzene, temperature of vaporization and standard enthalpy of formation of liquid and gaseous benzene (at 298 K)?

Answer 1

To calculate the enthalpy of vaporization of benzene at the vaporization temperature, you can use the following equation:

ΔH_vap = ΔH_fus + ΔH_vap_gas - ΔH_fus_gas

where: ΔH_vap is the enthalpy of vaporization ΔH_fus is the enthalpy of fusion ΔH_vap_gas is the standard enthalpy of vaporization of the gas phase benzene ΔH_fus_gas is the standard enthalpy of fusion of the gas phase benzene

To calculate the enthalpy of vaporization, you need the heat capacity of liquid benzene (Cp_liquid), the heat capacity of gaseous benzene (Cp_gas), the temperature of vaporization (T_vap), and the standard enthalpy of formation of liquid and gaseous benzene (ΔH_fus and ΔH_fus_gas) at 298 K.

The enthalpy of fusion (ΔH_fus) is given by:

ΔH_fus = Cp_liquid * (T_vap - 298 K)

The standard enthalpy of vaporization of the gas phase (ΔH_vap_gas) is given by:

ΔH_vap_gas = Cp_gas * (T_vap - 298 K)

The standard enthalpy of fusion of the gas phase (ΔH_fus_gas) is given by:

ΔH_fus_gas = ΔH_fus + ΔH_vap_gas

Finally, you can substitute these values into the first equation to calculate the enthalpy of vaporization (ΔH_vap).

Note: Make sure the units for temperature and heat capacity are consistent (e.g., Kelvin and Joules).