Question

A compressed air tank carriedby scuba divers has a volume of 8.0L and a pressure of 140atm at 20 degrees celsius. What is the volume of air in the tank in liters at STP?

Answer 1

We know that PV = nRT

Where

T = Temperature ;P = pressure ; n = No . of moles ;R = gas constant ; V= Volume of the gas

As the gas remains the same , n will constant

So PV / T = constant

Thereby PV/T = P'V'/T'

Where

P = initial pressure = 140 atm

V = initial volume = 8.0 L

T = initial temperature = 20 ^oC = 20+273 = 293 K

At STP conditions , P'= final pressure = 1.0 atm

V' = final volume = ?

T' = final temperature = 273 K

Plug the values we get V' = ( PVT') / (TP')

                                     = 1043.5 L

Therefore the volume of air tank at STP is 1043.5 L