9.3 Boyle's Law
Notes
Boyle's law: at constant temperature and amount of gas, pressure and volume are inversely proportional.
- $P_1V_1 = P_2V_2$.
- Squeeze a gas into half the volume and its pressure doubles.
- Why: in a smaller space, particles hit the walls more often.
- Example: 4.0 L at 1.0 atm compressed to 2.0 atm: $\displaystyle V_2 = \frac{(1.0)(4.0)}{2.0} = 2.0$ L.
Practice
A gas occupies 12.0 L at 1.50 atm. At constant temperature, it is compressed to 4.00 L. What is the new pressure?
$\displaystyle P_2 = \frac{(1.50)(12.0)}{4.00} = 4.50$ atm.
A balloon has a volume of 6.00 L at 100.0 kPa. What is its volume at 150.0 kPa if temperature stays the same?
$\displaystyle V_2 = \frac{(100.0)(6.00)}{150.0} = 4.00$ L. Higher pressure means smaller volume.
If the pressure on a gas is tripled at constant temperature, its volume:
$P$ and $V$ are inversely proportional.
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