A pistoncylinder assembly has air at 1 bar and 20o C It is s

A piston-cylinder assembly has air at 1 bar and 20o C. It is safe to:

a. Assume air behaves as an real gas.

b. Assume air behaves as an ideal gas with constant specific heats.

c. Assume the system is adiabatic.

d. None of the above are good assumptions.

Solution

Air behaves as an ideal gas under standard temperature and pressure conditions i.e. temperature of 273.15 K (0 °C, 32 °F) and an absolute pressure of 101.325 kPa (14.7 psi, 1.00 atm, 1.01325 bar).

Here air is at 1 bar and 20 ^oC so it is not safe to assume air as an ideal gas.

There is no mention of the system conditions hence it is not safe to assume it as adiabatic.

Finally, it is safe to assume air behaves as an real gas. Option a is correct.