The molecular velocity of a gas is directly related to molecular mass. Gases composed of lighter molecules have more high-speed particles and a higher u rms , with a speed distribution that peaks at relatively higher velocities. Gases consisting of heavier molecules have more low-speed particles, a lower u rms , and a speed distribution that peaks at relatively lower velocities.
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Login processing Chapter 5: Gases. Chapter 1: Introduction: Matter and Measurement. Chapter 2: Atoms and Elements. Chapter 3: Molecules, Compounds, and Chemical Equations. Chapter 4: Chemical Quantities and Aqueous Reactions.
Chapter 6: Thermochemistry. Chapter 7: Electronic Structure of Atoms. Chapter 8: Periodic Properties of the Elements. Chapter 9: Chemical Bonding: Basic Concepts. Chapter Liquids, Solids, and Intermolecular Forces. Chapter Solutions and Colloids. Chapter Chemical Kinetics. Chapter Chemical Equilibrium. Chapter Acids and Bases. Chapter Acid-base and Solubility Equilibria. Chapter Thermodynamics. Chapter Electrochemistry. Chapter Radioactivity and Nuclear Chemistry.
Chapter Transition Metals and Coordination Complexes. Chapter Biochemistry. Full Table of Contents. A portion of the energy of the ball is lost each time it hits the floor, until it eventually rolls to a stop. In this apparatus, the collisions are perfectly elastic. The balls have just as much energy after a collision as before postulate 5. Any object in motion has a kinetic energy that is defined as one-half of the product of its mass times its velocity squared.
At any time, some of the ball bearings on this apparatus are moving faster than others, but the system can be described by an average kinetic energy. When we increase the "temperature" of the system by increasing the voltage to the motors, we find that the average kinetic energy of the ball bearings increases postulate 6. The kinetic molecular theory can be used to explain each of the experimentally determined gas laws.
The pressure of a gas results from collisions between the gas particles and the walls of the container. Each time a gas particle hits the wall, it exerts a force on the wall. An increase in the number of gas particles in the container increases the frequency of collisions with the walls and therefore the pressure of the gas. Amontons' Law P T. The last postulate of the kinetic molecular theory states that the average kinetic energy of a gas particle depends only on the temperature of the gas.
Thus, the average kinetic energy of the gas particles increases as the gas becomes warmer. Because the mass of these particles is constant, their kinetic energy can only increase if the average velocity of the particles increases. The faster these particles are moving when they hit the wall, the greater the force they exert on the wall.
Since the force per collision becomes larger as the temperature increases, the pressure of the gas must increase as well. Gases can be compressed because most of the volume of a gas is empty space. If we compress a gas without changing its temperature, the average kinetic energy of the gas particles stays the same. There is no change in the speed with which the particles move, but the container is smaller. Thus, the particles travel from one end of the container to the other in a shorter period of time.
This means that they hit the walls more often. Any increase in the frequency of collisions with the walls must lead to an increase in the pressure of the gas. Thus, the pressure of a gas becomes larger as the volume of the gas becomes smaller. Charles' Law V T. The average kinetic energy of the particles in a gas is proportional to the temperature of the gas. Because the mass of these particles is constant, the particles must move faster as the gas becomes warmer.
If they move faster, the particles will exert a greater force on the container each time they hit the walls, which leads to an increase in the pressure of the gas. If the walls of the container are flexible, it will expand until the pressure of the gas once more balances the pressure of the atmosphere. The volume of the gas therefore becomes larger as the temperature of the gas increases. Join Now Already a member? Log In. New resources. Straight to your inbox. Sign up to our newsletter. Cookies We use cookies to improve your experience on our website.
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