Answer to Question #205151 in Chemistry for andrew

Question

A sample of helium gas takes up 15 L. After being compressed down to a volume of 8 L, the sample has a pressure of 4.3 atm. What was the original pressure? 

Answer 1

P₁ = unknown

V₁ = 15 L

P₂ = 4.3 atm

V₂ = 8 L

T₁ = T₂ = const

Solution:

Since the temperature and amount of gas remain unchanged, Boyle's law can be used.

Boyle's gas law can be expressed as: P₁V₁ = P₂V₂

To find the original pressure, solve the equation for P₁:

P₁ = P₂V₂ / V₁

P₁ = (4.3 atm × 8 L) / (15 L) = 2.29 atm = 2.3 atm

P₁ = 2.3 atm

Answer: 2.3 atm is the original pressure.