Air flows steadily between two sections in a duct. At section 1, the temperature and pressure are T1 = 90 °C and p1 = 310 kPa(abs). At section 2, the temperature and pressure are T2 = 200 °C and p2 = 195 kPa(abs). Calculate the change between sections 1 and 2 in:
(a) internal energy,
(b) enthalpy,
(c) density, and
(d) entropy.