Describe the motion of particles of a gas according to KINETIC THEORY. Taylor Bryant and Becky Brown

What is the Kinetic Theory? 1) All matter is composed of very small particles called atoms, ions or molecules. 2) All of these small particles are in constant motion, even at the coldest temperature whether vibratory or translatory. 3)The kinetic energy of the particles is a measure of temperature. The greater the number of impacts the greater will be the pressure and vice-versa. 4) These particles collide but the total energy remains same.

Movement of Particles Kinetic theory is the theory that gases are made up of a large number of small particles (atoms or molecules), all of which are in constant, random motion. The rapidly moving particles constantly collide with each other and with the walls of the container. Kinetic theory explains macroscopic properties of gases, such as pressure, temperature, or volume, by considering their molecular composition and motion. Essentially, the theory says that pressure is due not to static repulsion between molecules, as was Isaac Newton's conjecture, but due to collisions between molecules moving at different velocities.

The Atoms

Meredith Mitchell & Lisa Solomon How to Use a Barometer to Measure Air Pressure & Gas Pressure in terms of Kinetic Theory Meredith Mitchell & Lisa Solomon

Barometer Barometer: device used to measure air pressure The mercury moves up and down depending on the pressure exerted by particles in air colliding with the surface of the mercury

Gas Pressure in terms of Kinetic Theory Kinetic Theory: all matter consists of tiny particles that are in constant motion. Gas Pressure: results from the force exerted by a gas per unit surface

Kinetic Energy: The energy an object has because of its motion Kinetic Theory: all matter consists of tiny particles that are in constant motion Kinetic theory as it applies to gases: Gas particles: small, hard spheres with an insignificant volume Motion of gas particles: rapid, constant and random Collisions between particles in a gas are perfectly elastic (Elastic: kinetic energy is transferred from one particle to another, kinetic energy remains constant) 9

Temperature of an ideal monatomic gas- A measure related to the average kinetic energy of its atoms in motion Average molecular kinetic energy is proportional to the temperature (in Kelvin) In this animation, the size of helium atoms relative to their spacing is shown to scale under 1950 atmospheres of pressure. (At room temperature) 10

Lower Temperature: Lower concentration of kinetic energy Higher Temperature: Greater variety of kinetic energy level 11

The Nature of Liquids Liquids in terms of the Kinetic Theory and how intermolecular forces effect liquids

Liquids in terms of The Kinetic Theory The particles in Liquids, like gases, have kinetic energy. This kinetic energy allows the particles to “flow” past on another. The ability for the particles in liquids to flow is what gives liquids an indefinite shape.

How Liquids are effected by intermolecular forces Unlike gases, the particles in liquids are attracted to one another. These attractions between particles are what keeps the particles in the liquid so close together. These attractions are also what give liquids a definite volume.

How Liquids are effected by intermolecular forces (cont’d) The strength of the intermolecular forces, and the motions the particles are making, determine the physical properties of liquids. Since the intermolecular forces within a liquid keep the particles so close to each other, changing the pressure on a liquid barely changes its volume. Since you can hardly condense them anymore than they already are, liquids, as well as solids, are known as condensed states of matter.

Boiling Point Relations with Vapor Pressure and Temperature By Brooke Callahan, Rebecca Olsho, Amanda Ritter, and Jess Spoll

The kinetic molecular energy increases as temperature increases. Boiling Point The rate of evaporation of a liquid increases as temperature increases.  The kinetic molecular energy increases as temperature increases.      - This is due to the fact that the particles absorb the energy given off by the heat which allows them to move faster and reach the necessary amount of energy to overcome the surface of the liquid. Therefore, boiling point is achieved when the particles throughout the liquid have enough energy to vaporize. Or in other words, boiling point is the temperature at which the vapor pressure of the liquid is equal to the vapor pressure of the external atmosphere.

Boiling Point and Pressure Changes Not all liquids boil at the same temperature   A change in altitude can effect the boiling point of water ex. At higher altitudes, the atmospheric pressure is lower than it is at sea level. Thus, the water boils at a lower temperature  Boiling is a cooling process similar to evaporation: particles with the highest kinetic energy escape 1st temperature of boiling liquid never rises above its boiling point the vapor pressure produced is at the same temperature as that of the boiling liquid however, the vapor's stored energy is much higher than the liquid's and thus, a burn from the steam is more severe

Chapter 13 States of Matter Point 5

Vaporization: liquid gas or vapor Called Evaporation when it occurs at the surface of a liquid that is not boiling *During evaporation, only those molecules with a certain minimum kinetic energy can escape from the surface of the liquid. (others are bound by attractive forces)

The the temperature, the faster a liquid evaporates Why? Kinetic Energy When evaporation happens, all the vapors with highest kinetic energy leaves first, so the temperature decreases

measure of the force exerted by a gas above a liquid VAPOR PRESSURE measure of the force exerted by a gas above a liquid In a system at constant vapor pressure, a dynamic equilibrium exists between the vapor and the liquid. The system is in equilibrium because the rate of evaporation of liquid equals the rate of condensation of vapor. temperature vapor pressure

Here’s a Manometer… this part shows the vapor pressure of the Hg in mm Open to air Also, look in page 10 of the objectives packet for more info

How does a manometer work? One end of a U-shaped glass tube containing mercury is attached to a container. The other end of the tube is open to the surrounding atmosphere. When there is only air in the container, the pressure is the same on both sides of the tube and the mercury level is the same in each arm of the tube. When a liquid is added to the container, the pressure in the container increases due to the vapor pressure of the liquid. The vapor pressure of the liquid pushes the mercury on the container side of the U-tube. The levels of mercury in the U-tube are no longer the same. You can determine the vapor pressure in mm of Hg by measuring the difference between the two levels of mercury. As the vapor pressure increases, so does the difference between the two levels.

Chapter 13 distinguishing S/L/G sublimation LIZ LIN DAVID LU REBEKAH LEE JUDY LEE

distinguish solids from gases and liquids Organization Attractive Forces Solid Orderly arrangement Particles tightly packed vibrate about fixed points Not easily compressed Crystalline (most) -strongest Gas -small, hard spheres -volume not significant -none -independent particle movement Liquid -similar to gas but closer -flows -medium -attraction to one another keeps liquid particles close to each other Condensed states of matter 26

distinguish crystal from glass Structure Appearance Crystal Arranged in orderly, repeating, 3-D pattern called Crystal Lattice Shape of crystal reflects arrangement of the particles Smallest group of particles that retain geometric shape of crystal is called Unit Cells -Seven groups/crystal systems (Cubic, Tetragonal, Orthorhombic, Monoclinic, Triclinic, Hexagonal, Rhombohedral) Glass -Lacks ordered internal structure/atoms randomly arranged (called amorphous solid) -Internal structure between solid and liquid -Transparent fusion product of inorganic substances -”Supercooled Liquids”

sublimation The change of a substance from a solid to a vapor without passing through the liquid state  occurs in solids with vapor pressures that exceed atmospheric pressure at room temperature. Ex. Dry ice

The reverse of sublimation!!! deposition The change of a substance from a vapor to a solid without passing through the liquid state The reverse of sublimation!!! Ex. frost on the windows