The Gas Laws

ProportionalityDirectly Proportional• As one variable goes up

the other goes up, or as one variable goes down the other goes down

• Both variables do the same thing

Indirectly Proportional• As one variable goes up

the other goes down• The two variables do

the opposite thing

Boyle’s Law

• P1V1 = P2V2

• Temperature is constant• Pressure (P) and volume (V) are indirectly

proportional

Cartesian Diver

1. Draw or describe the initial observation2. Claim: If the pressure inside the bottle is

increased then…3. What are the variables? (list in table)4. What is the Gas Law relationship? (write the

gas law and proportionality)

Demo

Marshmallow Madness 1. Draw or describe the initial observation2. Claim: If the pressure inside the syringe is

decreased then…3. What are the variables? (list in table)4. What is the Gas Law relationship? (write the

gas law and proportionality)

Demo

Example 1A helium balloon was compressed from 4.0L to 2.5L at a constant temperature. If the pressure of the gas in the 4.0L balloon is 210 kPA, what

will the pressure be at 2.5L?Given:

V1 = 4.0L V2 = 2.5LP1= 210 kPa P2 = ?

P1V1 = P2V2

(210 kPa) × (4.0L) = P2 × (2.5L)P2 = 336 kPa ≈ 340 kPa

Example 2

A sample of neon gas occupies 0.200L at 0.860 atm. What will be its volume at 29.2 kPa

pressure?Given:

V1 = 0.200L V2 = ?P1= 0.860 atm P2 = 29.2 kPa

P1V1 = P2V2

(87.1 kPa) × (0.200L) = (29.2 kPa) × V2

V2 = 0.597L**Units must match for each variable (doesn’t matter which one is converted)

0.860 atm 101.3 kPa 1 atm = 87.1 kPa

Charle’s Law

• V1 V2

T1 T2

• Pressure is constant• Temperature must be in Kelvin• Volume (V) and temperature (T) are directly

proportional

=

1. Draw or describe the initial observation2. Claim: If the temperature inside the flask is

decreased then…3. What are the variables? (list in table)4. What is the Gas Law relationship? (write the

gas law and proportionality)

DemoBalloon in a Bottle

Example 1A gas ample at 40.0°C occupies a volume of 2.32L. If the temperature is raised to 75.0°C, what will the volume be, assuming the pressure remains constant?

Given:T1 = 40.0°C = 313K T2 = 75.0°C = 348KV1= 2.32L V2 = ?

V1 V2

T1 T2

=

2.32L V2

313 348=

V2 = 2.58L

Example 2A gas ample at 55.0°C occupies a volume of 3.50L. At what new temperature in kelvin will the volume increase to 8.00L?

Given:T1 = 55.0°C = 328K T2 = ?V1= 3.50L V2 = 8.00L

V1 V2

T1 T2

=

3.50L 8.00 328 T2

=

T2 = 750K

Gay-Lussac’s Law

• P1 P2

T1 T2

• Volume is constant• Temperature must be in Kelvin• Pressure (P) and temperature (T) are directly

proportional

=

Can Crusher

1. Draw or describe the initial observation2. Claim: If the temperature inside the bottle is

increased and suddenly decreased then…3. What are the variables? (list in table)4. What is the Gas Law relationship? (write the

gas law and proportionality)

Demo

Boiling Water

1. Draw or describe the initial observation2. Claim: If the temperature inside the flask is

decreased then…3. What are the variables? (list in table)4. What is the Gas Law relationship? (write the

gas law and proportionality)

Demo

Egg in a Bottle

1. Draw or describe the initial observation2. Claim: If the temperature inside the bottle is

increased then…3. What are the variables? (list in table)4. What is the Gas Law relationship? (write the

gas law and proportionality)

Demo

Example 1The pressure of a gas in a tank is 3.20 atm at 22.0°C. If the temperature rises to 60.0°C, what will be the gas pressure in the tank?

Given:P1 = 3.20 atm P2 = ?T1= 22.0°C = 295K T2 = 60.0°C =333K

P1 P2

T1 T2

=

3.20 atm P2

295K 333K=

P2 = 3.61 atm

Example 2A rigid container has a gas at constant volume at 665 torr pressure when the temperature is 22.0C. What will the pressure be if the temperature is raised to 44.6C?

Given:P1 = 665 torr P2 = ?T1= 22.0°C = 295K T2 = 44.6°C =317.6K

P1 P2

T1 T2

=

665 torr P2

295K 317.6K=

P2 = 716 atm