1. Gases
Boyle’s Law

2. Boyle’s Law As the volume of a gas increases, the pressure decreases.
temperature and number of gas particles remain constant

3. Symbolic Representation of Boyle’s Law
As volume increases, pressure decreases
Pressure and temperature are inversely proportional
Pressure (atm)
Volume (L)
How is this represented in the form of an equation?
P1V1 = P2V2

4. Units of Measuring Pressure
Many ways to measure pressure of a gas…
Atmospheres (atm): force per unit area exerted against a surface by the weight of air above that surface in the Earth’s atmosphere.
Millimeters of mercury (mm Hg): pressure of 1 mm of mercury in a column of mercury
torr: equal to 1 mm Hg
Pascals (Pa) or kilopascals (kPa)
We will use atmospheres (atm)

5. Boyle’s Law Example #1
A balloon contains 20.0 L of helium gas at 1.02 atm. The balloon rises to an altitude where the pressure is only 0.15 atm. What is the volume of the balloon at the higher altitude?
Step #1: Qualitative Assessment of the Problem
Step #2: Quantitative Assessment of the Problem

6. Boyle’s Law Example #2
A gas with a volume of 4.00 L at a pressure of 2.02 atm is allowed to expand to a volume of 12.0 L. What is the pressure in the container if the temperature remains constant?
Step #1: Qualitative Assessment of the Problem
Step #2: Quantitative Assessment of the Problem