Chem 111 heLP !

Question

Methane gas is compressed from 20L to 2.5L at a constant temperature. The final pressure is 12.2atm. What was the original pressure?

Answer 1

We will use Boyle's Law that states pressure is inversely proportional volume. This is given as:

P₁V₁ = P₂V₂

P₁ = ? P₂ = 12.2 atm

V₁ = 20 L V₂ = 2.5 L

P₁V₁ = P₂V₂ Substitue in values

P₁(20L) = 12.2 atm(2.5 L) Solve for P₁. Notice that the units L will cancel, leaving the unit atm.

P₁ = 1.525 atm

If you check this answer, you will find both sides will equal 30.5, which follows what we expect for Boyle's Law.