Embed Size (px)
DESCRIPTION
Kinetic Molecular Theory Empirical (based on experiments) description of gases that the gas laws are based on.
Citation preview
Agenda
• Behavior of Gases• Gas Laws• Gas Laws Worksheet
Closed System
A closed system does not
exchange matter with its
surroundings but energy can
come and go as it pleases.
Kinetic Molecular Theory
Empirical (based on
experiments) description of
gases that the gas laws are
based on.
Collisions of Gas Particles
Kinetic Molecular Theory
Kinetic Molecular Theory
Postulate (Assumption) 1
Gases consist of tiny particles
(atoms or molecules)
Kinetic Molecular Theory
Postulate (Assumption) 2These particles are so small, compared with the distances between them, that the volume (size) of the individual particles can be assumed to be negligible (zero).
Kinetic Molecular Theory
Postulate (Assumption) 3The particles are in constant random motion, colliding with the walls ofthe container. These collisions with the walls cause the pressure exertedby the gas.
Kinetic Molecular Theory
Postulate (Assumption) 4The particles are assumed not to attract or to repel each other.
Kinetic Molecular Theory
Postulate (Assumption) 5The average kinetic energy of the gas particles is directly proportional to the temperature of the gas
Ideal GasesParticles in an ideal gas…
have no volume.have elastic collisions. (When they collide no energy is lost)are in constant, random, straight-line motion.don’t attract or repel each other.have an avg. KE directly related to Kelvin temperature.
Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem
Real GasesParticles in a REAL gas…
have their own volumeattract each other
Gas behavior is most ideal…at low pressuresat high temperaturesin nonpolar atoms/molecules
Kinetic Molecular TheoryGases expand to fill any container.
random motion, no attraction
Gases are fluids (like liquids).
no attraction
Gases have very low densities.
no volume = lots of empty space
Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem
Gas Variables
žFour variables to describe a gas:
Pressure (P)Volume (V)Temperature (T)Amount (n)
Ideal Gas Relationships
As Pressure Increases, Temperature IncreasesBy extension – As Pressure Decreases Temperature Decreases
As Volume Increases, Temperature AND Pressure DecreaseBy extension – As Volume Decreases, Temperature and Pressure Increase
As Amount (number of moles) Increases, Pressure and Temperature Increase
By extension – As Amount Decreases, Pressure and Temperature Decrease
In a Closed System…
Gas Law Apparatus
Air Valve
Temperature Sensor
Pressure Gauge
Air Volume
