Do Now (5 min)
1. What happens to the pressure of a gas when you raise
the temperature?
2. What happens to the pressure of a gas when you
INCREASE the volume?
Do Now Discussion
What happens to the pressure of a gas when you raise
the temperature?
Pressure INCREASES
What happens to the pressure of a gas when you
INCREASE the volume?
Pressure DECREASES
Announcement!
Due to construction, we will be changing to a different
room for the rest of the school year:
 Period 1: Room 235
 Period 3: Room 211
 Period 6: Room 215
 Period 7: Room 219
 Period 9: Room 222
4-18-10
Cornell Notes
Worksheet Relay
Agenda
 Do Now
 Cornell Notes (3 gas laws)
 Worksheet Relay
Remember…
 Gases have four different properties we can measure in
numbers:
 According to Kinetic Molecular Theory, gases have
these properties because they are made of moving
particles.
Why are we learning about gases?
 Gases affect our lives in many ways
 We need it to survive (oxygen)
 Air pressure is responsible for our ears and lungs to
function
 To predict these behaviors, we need to be able to use
the three gas laws that gases obey.
Boyle’s Law
P α 1/V
 Pressure and volume are
INVERSELY proportional if moles
and temperature remain constant
 When P goes up, V goes down
and vice versa
P1V1 = P2V2
Robert Boyle
(1627-1691).
Son of Earl of
Cork, Ireland.
Example:
If the pressure of a gas starts at 2 atm and it’s volume is
5.0 L, what happens to the pressure when the volume
increases to 15.0 L?
P1V1 = P2V2
Before
(2 atm)(5.0 L)
(15.0 L)
After
=
(x atm)(15.0 L)
(15.0 L)
If we change the temperature, the pressure
changes to 0.67 atm
Boyle’s Law
 A bicycle pump is a
good example of
Boyle’s law.
 As the volume of the
air trapped in the
pump is reduced, its
pressure goes up, and
air is forced into the
tire.
Charles’s Law
VαT
 Volume and temperature are
DIRECTLY proportional IF moles
and pressure remain constant
 When V goes up, T goes up
V1 = V2
T1 T2
Jacques Charles (17461823). Isolated boron and
studied gases. Balloonist.
Example:
If the volume of a gas is 4.0 L and it’s temperature is 50
K, what happens to the volume if the temperature
changes to 75 K?
Before
4.0 L
50 K
V1 = V2
T1 T2
=
After
XL
75 K
If we change the temperature, the volume
changes to 6.0 L
Charles’s Balloon
 Heat up the air (raise the
tempreature), the volume
increases (balloon inflates)
Gay-Lussac’s Law
PαT
 Pressure and temperature are
DIRECTLY proportional IF moles
and volume remain constant
 When P goes up, T goes up
P1 = P2
T1 T2
Joseph Louis GayLussac (1778-1850)
Example
If the pressure of a gas is 5.0 atm and the temperature is
50 K, what will the temperature be if the pressure
decreases to 3.0 atm?
Before
P1 = P2
T1 T2
5.0 atm
50 K
=
After
3.0 atm
XK
If we change the pressure, the temperature
drops to 30 K
Combined Gas Law
 Good news! We don’t have to memorize all three laws!
Since they’re all related, we can combine them into
ONE equation!
• If you only need one of the other gas laws, you can
cover up the item that is constant and you will get
that gas law!
P1 V1
T1
=
P2 V2
T2
Boyle’s Law
Charles’ Law
Gay-Lussac’s Law
Practice
 Complete the worksheet problems on a SEPARATE
sheet of paper
 Have Ms. Akagi check your work after each round
BEFORE you move on to the next round!