The Role Of Kinetic Energy In Physical Changes

1. The Role Of Kinetic Energy In Physical Changes By:Michael Lau Jasmine Li Canita Mai

2. Overview In order to understand the role of kinetic energy in physical changes, a basic understanding of the 3 different types of kinetic energy that molecules possess is required. The 3 Subsections Of Our Presentation • The 3 Types of Kinetic Energy • Practical Applications of Kinetic Energy Changes • How Kinetic Energy Changes Phases

3. The 3 Types of Kinetic Energy As we already know, all molecules are in constant motion. In this first subsection, we will explore how kinetic energy makes molecules move.

4. The 3 Types of Kinetic Energy Hey! I am a water molecule, and I will be showing you how these different types of kinetic energy affect me! • Rotational Energy • Symbol: EROT • How it makes molecules move: This type of kinetic energy makes molecules rotate around an axis, however, the bond between the atoms do not change • Examples:

5. The 3 Types of Kinetic Energy 2. Vibrational Energy • Symbol: EVIB • How it makes molecules move: This type of kinetic energy changes the bond lengths and angles between the atoms • Examples: There are several ways this kinetic energy affects the bond lengths! But remember, this kinetic energy changes the relative movement of the atoms of a molecule. 1. 2. 3.

6. The 3 Types of Kinetic Energy 3. Translational Energy • Symbol: ETRANS • How it makes molecules move: This kinetic energy causes molecules to travel in a straight line from one location to another. However, this kinetic energy does not affect the bond length or angle. • Examples: I will move in a straight line, until I pump into an obstacle, in that case, I will travel in the opposite direction.

7. Practical Applications of Kinetic Energy Of Molecules The two common applications of vibrational kinetic energy in molecules are described below: Microwave Ovens: How it works: The microwave supplies water molecules in the food the kinetic energy it needs to vibrate back and forth. The molecules absorb the heat and thus its bonds are able to stretch back and forth. (see diagram on EVIB) What this does: This application of kinetic energy in molecules allow food to be heated in a relatively shorter time.

8. Practical Applications of Kinetic Energy Of Molecules Infrared Spectroscopy: How it works: An unknown molecule is put under the exposure of IR energy, which is simply a type of heat energy. Because different molecules have different bonds, the molecules will vibrate in different ways, with the supply of heat energy. What this does: This application allows for the identification of different types of molecules.

9. The Role Of Kinetic Energy In Phase Changes The phase changes of, in this case, water, are greatly assisted by the kinetic energy of each H2O molecule when heat is added.

10. The Role Of Kinetic Energy In Phase Changes

11. Thank you for listening, and we hope you learned something new!

12. Bibliography *Please note: all diagrams were done by computer, they were not from internet. Text Source: Hebden, James A. Hebden: Chemistry 11, A Workbook for Students. Kamloops, BC: 1998. Picture Sources: http://cirellio.files.wordpress.com/2008/06/boiling-water.jpg http://carol.gimp.org/writing/images/Ice_cubes_openphoto.png http://www.dailygalaxy.com/photos/uncategorized/2007/10/03/magic_gamma_rays.jpg http://www.appliancist.com/ge-cafe-over-the-range-microwave-oven.jpg http://das.okstate.edu/EXCEL/This%20Water%20Drop.jpg http://www.moorewallpaper.com/Water-11.jpg http://www.acclaimimages.com/_gallery/_pages/0093-0509-2111-5314.html