Gay-Lussac’s Law: The Relationship between Pressure and Temperature of a Gas
Objectives: define, apply, and calculate Gay-Lussac’s Law and Charles’ Law
In Gay-Lussac’s Law, the constant variables are:
1. Amount of gas (moles, mass, particles)
2. Volume of a gas
Explain Gay-Lussac’s Law
Think about 10 molecules of gas trapped in a syringe.
• Use temperature as the independent variable
• Apply Kinetic Theory
When you increase the Kelvin temperature of a fixed number of particles of gas, the
particles will move faster. This motion means they will collide more. These collisions are
pressure and therefore it will increase.
NOTE: This relationship can also be explained in reverse…with a decrease in
temperature and therefore pressure.
Define Gay-Lussac’s Law-
When the amount of gas and volume are constant, the pressure of a gas varies
directly with the KELVIN temperature
Application: Explain how the development of gas pockets in bread is an application of
Gay-Lussac’s Law
“Yeast produces carbon dioxide gas. When baked, the carbon dioxide
increases in temperature. The carbon dioxide molecules move
faster increasing the pressure”.
Alternate Formula:
P1 P2

T1 T2
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The gas left in a used aerosol can is at a pressure of 103 kPa at 25˚C. If this can is thrown onto a
fire, what is the pressure of the gas when its temperature reaches 928˚C?
Charles’ Law: The Relationship between Temperature and Volume of a Gas
In Charles’, the constant variables are:
1. Amount of gas (moles, mass, or particles)
2. pressure
Explain Charles’ Law
Think about 10 molecules of gas trapped in a syringe.
• Use temperature as the independent variable
• Apply Kinetic Theory
When you increase the Kelvin temperature of a fixed number of particles of gas, the
particles will move faster. This motion means they will collide more. These collisions
are elastic and therefore adjacent molecules will be farther apart which increases
volume.
NOTE: This explanation works in the reverse as well. A decrease in Kelvin
temperature will result in a decrease in volume.
Define Charles’ Law-
When the amount of gas and pressure are constant, the volume of a gas varies
directly with the KELVIN temperature
Application:
Explain how the expansion of gas pockets in bread is an application of Charles’ Law
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“Yeast produces carbon dioxide gas. When baked, the carbon dioxide increases in
temperature. The carbon dioxide molecules move faster and collide more thus
increasing the distance between them and thus the volume”
Alternate Formula:
V1 V2

T1 T2
A balloon inflated in a room at 24˚C has a volume of 4.00 L. The balloon is then heated to a
temperature of 58˚C. What is the new volume if the pressure remains constant?
How do I get from where I am to where I’m going?
10 Minute Makeover
 Complete the “Gay-Lussac’s Law” and “Charles’ Law sections on the Portfolio Page
 Review the PPT file on the website
 Read pages 335-340 in the book
 Extra practice problems: page 356 #55 and #57-answers in Appendix C
 Quia Multiple Choice Practice: http://www.quia.com/rr/333482.html
 Check out the tutorial sources in the LiveBinder
 Complete the eligible content on the SYS Assignment
 Review the skills from today’s Train Your Brain
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