1. Module 3 Intro

1.15. Page 2

Lesson 3

Module 3—Behaviour of Gases

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In Lessons 1 and 2 of this module you referred to the kinetic molecular theory of matter to help you visualize the behaviour of gas particles explained by the gas laws you have studied.  This theory can be used to develop a model that explains the physical behaviour of gases. In the gas phase, all pure substances show remarkably similar physical behaviour.

 

In your experiments conducted thus far, the relationships among pressure, volume, and temperature by Boyle’s law and Charles’ law were verified with all the gases tested. What is true for nitrogen is true for oxygen, hydrogen, and any other gas. The behaviour of gases is independent of the type of gas present. The fact that different gases resemble each other so closely in their physical behaviour has some interesting results.

 

Read pages 163 and 164 in your textbook to review a summary of the application of concepts of the kinetic molecular theory to what you have learned thus far in this module.

 

Self-Check

 

SC 1.    Complete “Practice” question 1 (a) through (e) on page 164 of your textbook.

 

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Self-Check Answers

 

SC 1.

  1. The kinetic molecular theory states that an increase in temperature represents an increase in the average kinetic energy and greater average speed of the particles in the system. Higher speeds of the particles will result in more collisions with the container the gas is held in. The greater the number of collisions, the greater the pressure exerted by the gas.

  2. Reducing the volume of the container forces the same number of particles to be contained in a smaller space. Since the temperature remains constant, so would their average speed, but the particles would now be colliding against a smaller surface. The result is an increase in the number of collisions. The greater the number of collisions, the greater the pressure exerted by the gas.

  3. Particles of gases have greater space between them and greater freedom of motion. Therefore particles of other gases are able to move into the spaces between other gas particles to mix quickly.

  4. In a hydraulic system, force applied to one end needs to be transferred to the other end.  Since gases are highly compressible, the force applied would not be efficiently transmitted as it would be with a liquid, which is not very compressible.

  5. Molecules are in constant motion, and therefore in a system containing many particles, they will collide often, changing the direction of colliding particles and making it very difficult for one particle to follow a straight path for a long distance. The bullet does not collide with an object that changes its path as readily as an oxygen or nitrogen molecule does.