"Find the total weight of an 18-ft3 tank of oxygen if the oxygen is pressurized to 184 psia, the tank itself weighs 150 lbf, and the temperature is 95°F."

Explanation:

1 psi = 6894.76 Pa

P = 184 psi = 12.686 x 10⁵ Pa .

Temperature T = 95⁰F = 35⁰C= 308 K

volume V = 18 ft³ = 18 x 0.0283168 m³

= .51 m³

From the gas law

PV/RT = n where n is mole of gas

= 12.686 x 10⁵ x  .51  / 8.31 x 308

= 252.78 gm mole

= 252.78 x 32 gm

= 8.08896 kg

= 2.20462 x 8.08896 lb

= 17.833 lb

= 17.833 / 32 lbf

= .5573 lbf

weight of tank = 150 lbf

Total weight = 150 + .5573

= 150.5573 lbf .