A tank of volume 590 L contains oxygen at 20 degree Celsius and 5.0 atm pressure. Calculate the mass of the oxygen in the tank.

There are two steps to solving this problem:

1. Find the number of moles of oxygen gas using the ideal gas law, PV=nRT.

2. Find the mass of the oxygen using mass = moles x molar mass.

Given information:

P = pressure = 5.0 atm

V = volume = 590 liters

T = temperature = (20ºC + 273) = 293 K

n = moles (unknown)

Other information needed:

R = ideal gas constant = 0.0821...

There are two steps to solving this problem:

1. Find the number of moles of oxygen gas using the ideal gas law, PV=nRT.

2. Find the mass of the oxygen using mass = moles x molar mass.

Given information:

P = pressure = 5.0 atm

V = volume = 590 liters

T = temperature = (20ºC + 273) = 293 K

n = moles (unknown)

Other information needed:

R = ideal gas constant = 0.0821 L-atm/mol-K

Molar mass of oxygen = 32.0 grams/mole

Rearrange PV = nRT to solve for n:

n = PV/RT = (5.0 atm)(590 L)/(0.0821 L-atm/mol-K)(293 K) = 122.6 moles

mass of oxygen = (122.6 moles)(32.0 g/mol) = 3924 g = 3.92 kg oxygen

Note that temperature must be in Kelvins when using gas law equations and that the value of R used must correspond to the pressure units given.