Table of Contents • Chapter Preview • 3.1 States of Matter • 3.2 Changes of State • 3.3 The Behavior of Gases
Section 3:The Behavior of Gases • What types of measurements are useful when working with gases? • When working with a gas, it is helpful to know its volume, temperature, and pressure.
Section 3:The Behavior of Gases • How are the volume, temperature, and pressure of a gas related?
A Change in Pressure • The pressure of the gas is the force of its outward push divided by the area of the walls of the container. • A punctured basketball deflates as gas particles begin to escape.
Temperature and Volume • When the temperature of a gas increases at constant pressure, its volume increases.
Pressure and Temperature • When a gas is heated, the particles move faster and collide more often with each other and with the walls of their container. The pressure of the gas increases.
Charles’ Law • Charles’ Law states that at constant pressure, the volume of the gas increases as its temperature increases. Likewise, as the volume of the gas decreases its temperature decreases.
Charles’ Law • The graph is directly proportional, that is, when a graph of two variables is a straight line passing through the origin.
Charles’s Law Video • Optional video for extra work htp://teachertube.com/viewVideo.php?video_id=92871&title=Gases_05___Charles_Law http://www.youtube.com/watch?v=IkRIKGN3i0k
Pressure and Volume • As weights are added, the gas particles occupy a smaller volume. The pressure increases.
Boyle’s Law • Boyle’s Law states that at constant temperature, the volume of a gas increases as its pressure decreases
Boyle’s Law • A graph of Boyle’s Law will be inversely proportional, which is when the product of two variables is a constant.
Gas Laws Activity • Click the Active Art button to open a browser window and access Active Art about gas laws. http://preparatorychemistry.com/Bishop_Boyles_Law_Flash1.htm
Graphing Gas Behavior In an experiment, the temperature of a gas at a constant volume was varied. Gas pressure (in kilopascals) was measured after each 5-kelvin change in temperature. The data from the experiment are shown in the table.
Graphing Gas Behavior Graphing Use the data to make a line graph. Plot temperature on the horizontal axis with a scale from 270 K to 300 K. Plot pressure on the vertical axis with a scale from 0 kPa to 25 kPa. (1 kPa = 1,000 Pa)
Graphing Gas Behavior Interpreting Data What was the manipulated variable in this experiment? Changing the temperature of a gas at constant volume changes its pressure in a similar way.
Graphing Gas Behavior Interpreting Data What kind of trend do the data show? Pressure increases with temperature.
Graphing Gas Behavior Drawing Conclusions What happens to the pressure of a gas when temperature is increased at constant volume? Gas pressure increases.