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 DiscussionWhat happens to the pressure of a gas when

you raise the temperature?

What happens to the pressure of a gas when you INCREASE the volume?

Pressure INCREASES

Pressure DECREASES

Announcement!Due to construction, we will be changing to a

different room for the rest of the school year:Period 1: Room 235Period 3: Room 211Period 6: Room 215Period 7: Room 219Period 9: Room 222

The Gas Laws4-18-10

Cornell NotesWorksheet Relay

AgendaDo NowCornell 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 LawP 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

After

(2 atm)

(5.0 L)

= (x atm)

(15.0 L)

(15.0 L)

(15.0 L)

If we change the temperature, the pressure changes to 0.67 atm

Boyle’s LawBoyle’s LawA 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 LawV α T

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 (1746-1823). 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?

V1 = V2

T1 T2

Before

After

4.0 L

50 K=

X L

75 K

If we change the temperature, the volume changes to 6.0 L

Charles’s BalloonHeat up the air (raise the

tempreature), the volume increases (balloon inflates)

Gay-Lussac’s LawP α T

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 Gay-Lussac (1778-1850)

ExampleIf 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?

P1 = P2

T1 T2

Before

After

5.0 atm50 K

=3.0 atmX K

If we change the pressure, the temperature drops to 30 K

Combined Gas LawGood 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

PracticeComplete the worksheet problems on a

SEPARATE sheet of paperHave Ms. Akagi check your work after each

round BEFORE you move on to the next round!