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?
P1 = unknown
V1 = 15 L
P2 = 4.3 atm
V2 = 8 L
T1 = T2 = const
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.