total mass?

Question

what is the total mass in grams of oxygen in a room measuring 4.0 m by 5.0 m by 2.5 m? assume that the gas is at STP and that air contains 20.95% oxygen by volume

Answer 1

First we need to know the total volume of the room, so:

 

V=l×w×h

  = 5m×4m×2.5m

  = 50m³

 

Now we need to know what is the mass of all the air in the room at STP:

 

 =50m³×1.2754 kg/m³

 = 63.77kg

 

Now we know that Oxygen is 20.95% of the total mass of the air, so

 

mass of oxygen= 63.77kg × .2095

mass of oxygen= 13.359815 kg