A sample of carbon dioxide gas is subject to a process where its temperature changes from an initial temperature of 300 K to a final temperature of 900 K.

Determine the enthalpy change of the carbon dioxide,

a. Using the Shomate equation for the ideal gas isobaric heat capacity

b. Assuming the ideal gas isobaric heat capacity is constant at the average temperature of the process Express your answers in kJ/kg. Compare the two approaches and comment on the validity of assuming constant heat capacity in this problem.