Given: P1 = Initial pressure = 5 bar
V1 = Initial volume = 500 dm3 ; V2 = Final volume = 200 dm3
To find: P2 = Final pressure
Formula: P1 V1 = P2 V2 (at constant n and T)
Calculation: According to Boyle’s law
P1 V1 = P2 V2 (at constant n and T)
∴ P2 = \(\frac{P_1V_1}{V_2}\) = \(\frac{5 \times 500}{200}\) = 12.5 bar
The minimum pressure required to compress 500 dm3 of air at 5 bar to 200 dm3 at 25 °C is 12.5 bar.