An air bottle used for scuba diving breathing apparatus has a volume of 30l. After it has been used, the pressure and temperature of the remaining air in the bottle are 0.3 MPa and 24 ◦C. Before the apparatus is used again, it is charged with air at temperature of 50 ◦C until the pressure in the bottle reaches 6 MPa. The charging processes is fast, and can be assumed to be adiabatic.

Questions:

(a) Calculate the mass of air to be added to the bottle.

(b) What is the temperature of the air in the bottle at the end of the charging process?