Boyle's Law Formula
Boyle's Law shows the relationship between the Pressure and Volume of a gas. Pressure and volume have a direct relationship, so if the volume goes up then the pressure goes down and if the pressure goes up then the volume goes down (and vice versa)
The equation for Boyle's Law is:
P1V1 = P2V2
P1 = Initial Pressure (atm or mmHg)
V1 = Initial Volume (L or mL)
P2 = Final Pressure (atm or mmHg)
V2 = Final Volume (L or mL)
Note: The units of pressure and volume do not matter however the units much match for both P1 and P2 and for V1 and V2.
Boyle's Law Formula Questions:
1.) A balloon contains 7.2L of He. The pressure is reduced to 2.00atm and the balloon expands to occupy a volume of 25.1L. What was the initial pressure exerted on the balloon?
Answer: For this problem the Initial Volume is V1 = 7.2L. We are asked to find the Initial Pressure (P1). The Final Pressure is P2 = 2.00atm and the Final Volume is V2 = 25.1L.
Plug into the Boyle's Law Equation
P1V1 = P2V2
P1(7.2L) = (2.00atm)(25.1L)
P1 = 6.97atm
The initial pressure exerted on the balloon was 6.97atm.
2.) 352mL of chlorine under a pressure of 680 mmHg are placed into a container under a pressure of 1210 mmHg. The temperature remains constant at 296K. What is the volume of the container?
Answer: The Initial Volume is V1 = 352mL. The Initial Pressure is P1 = 680 mmHg. The Final Pressure is P2 = 1210 mmHg. The Final Volume (V2) is what we are trying to find in the problem.
Plug into the Boyle's Law Equation
P1V1 = P2V2
(680 mmHg)(352 ml) = (1210 mmHg)( V2)
V2 = 197.82 mL
The volume of the container would be 197.82 mL