Boyles Law

1
Boyles Law

• Pressure vs. Volume

2
Why Do We Care?

• Boyles Law lets you breathe!

3

• Boyle's Law is also very important in diving.
  In diving, the lungs are under intense pressure,
  and so that drastically changes volume. If you
  take a breath at the surface of a body of water,
  it is at a pressure of about 15 psi from the
  atmosphere. If you dive to a depth of about 33
  feet or 10 meters (slightly less for salt water),
  the pressure will double to 30 psi. The volume of
  your lungs will be halved! And if you take a full
  breath of compressed air at 33 ft, heading back
  to the surface the volume of that air will
  double! That's why you have to exhale on the
  return trip, or else your lungs would explode.

4
Boyles Fabulous Formula!

• P1V1 P2V2
• Its a INVERSE relationship. As one value goes
  up the other goes down (vice versa)
• http//www.chem.iastate.edu/group/Greenbowe/secti
  ons/projectfolder/flashfiles/gaslaw/boyles_law_gra
  ph.html

5
Boyle Blew Off Temperature!

• Boyles Law just compares the effects of
  PRESSURE (P) and VOLUME (V)
• We assume the temperature (T) does not change.

6
Lets Solve a Problem!

• If 50 mL of oxygen gas is compressed from 20 atm
  of pressure to 40 atm of pressure, what is the
  new volume at constant temperature?

7
1. Identify your variables

• If 50 mL (V1) of oxygen gas is compressed from 20
  atm (P1) of pressure to 40 atm (P2) of pressure,
  what is the new volume (V2) at constant
  temperature?

8
2. Plug values into equation

• 20 atm (P1) X 50 mL (V1) 40 atm (P2) X V2
• 1000 40 (V2)
• V2 1000/40 or 25 mL
• Solving for V2 we get 25 mL as our answer.

9
Time for The Happy Dance!
(and to work some problems)