If gas with a volume of 100 cubic inches has 30 pounds of pressure, find the amount of pressure 150 cubic inches of gas is under.

Question

Find the amoun t of pressure.

Answer 1

Marie, is constant temperature included in the original problem statement? I am assuming it is.  If the gas is at constant temperature, then Boyle's law applies, which states that at constant temperature, pressure and volume are inversely proportional:

 

P₁V₁ = P₂V₂

 

P₁ = 30 pounds 

V₁ = 100 cubic inches

P₂ = ?

V₂ = 150 cubic inches

 

P₂ = P₁V₁ / V₂ = (30 pounds )(100 cubic inches) / (150 cubic inches) = 20 pounds

 

Answer 2

Set up a proportion.

 

Ratio of volume = ratio of pressure

 

100 / 150 = 30 / x

 

where  x is the pressure when the gas has a volume of 150 in³.

 

 

All you have to do is solve for x from the proportion.