A mass of 56 g of di-nitrogen (molar mass of 28 g mol1 ), considered as an ideal gas, undergoes an irreversible isothermal expansion in the vacuum (Joule's expansion), from an initial pressure of 2 atm to the normal atmospheric pressure. using two different paths:

1. Determine the entropy variation considering a reversible isothermal process.

2. Determine the entropy variation considering a reversible adiabatic process until atmospheric pressure, followed by a reversible isobaric heating.