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Gases Day 2. Standard 4:The kinetic molecular theory describes the motion of atoms and molecules and explains the properties of gases. Objective. Catalyst. I can explain gas properties using the kinetic molecular theory of gases. Turn in your reading questions from last class.
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Gases Day 2 Standard 4:The kinetic molecular theory describes the motion of atoms and molecules and explains the properties of gases.
Objective Catalyst • I can explain gas properties using the kinetic molecular theory of gases. • Turn in your reading questions from last class. • Convert the temperatures into Kelvin: (write on a whiteboard) • Warmest November day in LA: 37.7° C (100° F) on November 1, 1966. • Coldest November day in LA: 1.1 ° C (34° F) on November 19, 1886. Agenda • Catalyst • Balloon in a bottle • KMT! Notes & Videos • KMT practice • Exit Slip
Bad Guys Like Gas, Why? • Write on a whiteboard: Video Focus Question: How does the gas move in the video? Thinking about how gases move, what are some benefits and disadvantages of using gas as a weapon? • http://www.youtube.com/watch?v=iOkPaSwXC6s
Mini Vocabulary Review • Volume • a measure of the size of an object in three dimensional space. • kinetic energy • the energy of an object that is due to the object’s motion. • Pressure • the amount of force exerted per unit area on a surface. • temperature • a measure of the average kinetic energy of the particles in an object.
The Kinetic Molecular Theory • The Kinetic Molecular Theory is a way to explain the properties of gases by examining the movement of gas particles at the microscopic level. • Gases that obey the Kinetic Molecular Theory are called Ideal Gases • Just like there are no “ideal” people, there are actually no ideal gases. But gases do approach ideal behavior.
The KINETIC MOLECULAR THEORY! 1. Gases consist of tiny particles (molecules or atoms). 2. The particles are TINY compared to the space between them. So, we do not count the volume of the particles. Space between = BIG Itty-bity Itty-bitty
KMT continued 3. The particles are in constant RANDOM motion. The particles collide with the walls of the container. These collisions result in pressure. Exerts pressure
More KMT! 4. The gas particles do not attract or repel each other. They move randomly. 5. The average kinetic energy of the gas is proportional to the Kelvin temperature. Kinetic Energy Temperature
Let’s use the KMT to explain some gas properties. Pressure & Temperature Diffusion Pressure & Volume Pressure & # of molecules We are about to do a demonstration and watch some videos. Take notes and draw pictures in the boxes on your worksheet. Think about how to explain what you see using the KMT (think about the constant and random motion of particles).
Diffusion • Diffusion is the movement of particles from regions of high concentration to low concentration. • The random movement of gas particles causes diffusion.
Pressure and Temperature • When temperature increases, pressure ________. • When temperature decreases, pressure _______. • http://www.youtube.com/watch?v=HiLeji8bLOk • Think, Pair, Share: What happened in the video and why?
Pressure and Volume • As volume increases, pressure ________. • As volume decreases, pressure _______. • http://www.grc.nasa.gov/WWW/k-12/airplane/aboyle.html • http://www.youtube.com/watch?feature=endscreen&v=ULdmv-iPQvA&NR=1 • Think, Pair, Share: What happened in the video and why?
Pressure and Number of Moles • As the number of molecules increases, pressure __________. • As the number of molecules decreases, pressure __________. • http://www.youtube.com/watch?v=t-Iz414g-ro • Think, Pair, Share: What happened in the video and why?
KMT Practice: Example • Richard bought a new soccer ball and it came deflated. As he pumps air molecules into the soccer ball, the pressure inside the soccer ball _________. Why? • With more molecules moving randomly and rapidly in the ball, they will hit the sides more, increasing pressure.
Practice • Work independently or with a partner. • Complete the practice problems and activity. • Challenge: Use a word processing or drawing application on your iPad to make your poster. Turn it in through the class edmodo page.
Homework • Complete any unfinished practice problems and your poster (paper or digital) • Read pp. 416-422 Do problems pp. 422 #1-7. (Additional resources on the class website) • Optional: Flashcards: diffusion, kinetic molecular theory, directly proportional, inversely proportional, density, compress
Exit Slip Answers 4a & 4b 4a: (1) Aerosol cans have a warning not to dispose of them in fires. Why? (use KMT) They are pressurized. The gas will explode when exposed to heat because the kinetic energy of molecules will increase until the pressure inside is too much for the can. (2) As the kinetic energy of molecules increases, the temperature _increases_. Why? Temperature is a measure of the kinetic energy of molecules. 4b: (3) Why does gas diffuse through air? The molecules move randomly, causing diffusion. (4) How are molecules of different chemicals arranged when diffusion is complete? They are all spread out and mixed together as much as possible. They form a homogenous mixture or solution.