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

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: Kinetic Energy: The energy an object The energy an object has because of its motionhas because of its motion

Kinetic Theory: Kinetic Theory: all matter consists of all matter consists of tiny particles that are in constant tiny particles that are in constant motion motion

Kinetic theory Kinetic theory as it applies to as it applies to gasesgases::–Gas particles: small, hard spheres with an Gas particles: small, hard spheres with an insignificant volumeinsignificant volume

–Motion of gas particles: rapid, constant and Motion of gas particles: rapid, constant and randomrandom

–Collisions between particles in a gas are Collisions between particles in a gas are perfectly elastic (perfectly elastic (Elastic: Elastic: kinetic energy is kinetic energy is transferred from one particle to another, transferred from one particle to another, kinetic energy remains constant)kinetic energy remains constant)

Temperature of an ideal monatomic Temperature of an ideal monatomic gas- A measure related to the gas- A measure related to the average kinetic energy of its atoms in average kinetic energy of its atoms in motionmotion

Average molecular kinetic energy is Average molecular kinetic energy is proportional to the temperature proportional to the temperature (in (in Kelvin)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)

•Lower Temperature: Lower concentration of kinetic energy

•Higher Temperature: Greater variety of kinetic energy level

The Nature of LiquidsThe Nature of Liquids

Liquids in terms of the Liquids in terms of the Kinetic Theory and how Kinetic Theory and how intermolecular forces intermolecular forces

effect liquidseffect liquids

Liquids in terms of The Kinetic Liquids in terms of The Kinetic TheoryTheory

The particles in Liquids, like gases, The particles in Liquids, like gases, have kinetic energy.have kinetic energy.

This kinetic energy allows the This kinetic energy allows the particles to “flow” past on another.particles to “flow” past on another.

The ability for the particles in liquids The ability for the particles in liquids to flow is what gives liquids an to flow is what gives liquids an indefinite shape.indefinite shape.

How Liquids are effected by How Liquids are effected by intermolecular forcesintermolecular forces

Unlike gases, the particles in liquids Unlike gases, the particles in liquids are attracted to one another.are attracted to one another.

These attractions between particles These attractions between particles are what keeps the particles in the are what keeps the particles in the liquid so close together.liquid so close together.

These attractions are also what give These attractions are also what give liquids a definite volume.liquids a definite volume.

How Liquids are effected by How Liquids are effected by intermolecular forces (cont’d)intermolecular forces (cont’d)

The strength of the intermolecular forces, The strength of the intermolecular forces, and the motions the particles are making, and the motions the particles are making, determine the physical properties of liquids.determine the physical properties of liquids.

Since the intermolecular forces within a Since the intermolecular forces within a liquid keep the particles so close to each liquid keep the particles so close to each other, changing the pressure on a liquid other, changing the pressure on a liquid barely changes its volume.barely changes its volume.

Since you can hardly condense them Since you can hardly condense them anymore than they already are, liquids, as anymore than they already are, liquids, as well as solids, are known as condensed well as solids, are known as condensed states of matter.states of matter.

Boiling Point Boiling Point Relations with Vapor Relations with Vapor

Pressure and Pressure and TemperatureTemperature

By Brooke Callahan, By Brooke Callahan, Rebecca Olsho, Amanda Rebecca Olsho, Amanda

Ritter, and Jess SpollRitter, and Jess Spoll

Boiling PointBoiling PointThe rate of evaporation of a liquid increases as The rate of evaporation of a liquid increases as

temperature increases. temperature increases. The kinetic molecular energy increases as temperature The kinetic molecular energy increases as temperature

increases. increases. 

        - This is due to the fact that the particles absorb the - This is due to the fact that the particles absorb the energy given off by the heat which allows them to energy given off by the heat which allows them to move faster and reach the necessary amount of move faster and reach the necessary amount of energy to overcome the surface of the liquid.energy to overcome the surface of the liquid.

Therefore, boiling point is achieved when the particles Therefore, boiling point is achieved when the particles throughoutthroughout the liquid have enough energy to the liquid have enough energy to

vaporize.vaporize.

Or in other words, boiling point is the temperature at Or in other words, boiling point is the temperature at which the vapor pressure of the liquid is equal to the which the vapor pressure of the liquid is equal to the

vapor pressure of the external atmosphere.vapor pressure of the external atmosphere.

Boiling Point and Pressure Boiling Point and Pressure ChangesChangesNot all liquids boil at the same temperatureNot all liquids boil at the same temperature

  A change in altitude can effect the boiling point of waterA change in altitude can effect the boiling point of water

ex. At higher altitudes, the atmospheric pressure is lower than ex. At higher altitudes, the atmospheric pressure is lower than it is at sea level. Thus, the water boils at a lower temperatureit is at sea level. Thus, the water boils at a lower temperature   

    Boiling is a cooling process similar to evaporation:Boiling is a cooling process similar to evaporation:

• particles with the highest kinetic energy escape 1st particles with the highest kinetic energy escape 1st • temperature of boiling liquid never rises above its boiling pointtemperature of boiling liquid never rises above its boiling point• the vapor pressure produced is at the same temperature as the vapor pressure produced is at the same temperature as

that of the boiling liquid that of the boiling liquid • however, the vapor's stored energy is much higher than the however, the vapor's stored energy is much higher than the

liquid's and thus, a burn from the steam is more severeliquid's and thus, a burn from the steam is more severe

Point 5Point 5

Vaporization: liquid gas or Vaporization: liquid gas or vaporvapor–Called Called EvaporationEvaporation when it occurs at the when it occurs at the surface of a liquid that is not boilingsurface of a liquid that is not boiling

*During evaporation, only those molecules *During evaporation, only those molecules with a certain minimum kinetic energy with a certain minimum kinetic energy can escape from the surface of the liquid. can escape from the surface of the liquid. (others are bound by attractive forces)(others are bound by attractive forces)

The the temperature, the The the temperature, the faster a liquid evaporatesfaster a liquid evaporates–Why? Kinetic Energy Why? Kinetic Energy

measure of the force exerted by measure of the force exerted by a gas above a liquida gas above a liquid

In a system at constant vapor In a system at constant vapor pressure, a dynamic equilibrium pressure, a dynamic equilibrium exists between the vapor and exists between the vapor and the liquid. The system is in the liquid. The system is in equilibrium because the equilibrium because the rate of rate of evaporation of liquid equals the evaporation of liquid equals the rate of condensation of vapor.rate of condensation of vapor.

measure of the force exerted by measure of the force exerted by a gas above a liquida gas above a liquid

In a system at constant vapor In a system at constant vapor pressure, a dynamic equilibrium pressure, a dynamic equilibrium exists between the vapor and exists between the vapor and the liquid. The system is in the liquid. The system is in equilibrium because the equilibrium because the rate of rate of evaporation of liquid equals the evaporation of liquid equals the rate of condensation of vapor.rate of condensation of vapor.

temperature vapor pressure

Also, look in page 10 of the objectives packet for more info

this part shows the vapor pressure of the Hg in mm

Open to air

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

LIZ LINLIZ LIN

DAVID LUDAVID LU

REBEKAH LEEREBEKAH LEE

JUDY LEEJUDY LEE

Chapter 13Chapter 13distinguishing S/L/Gdistinguishing S/L/G

sublimationsublimation

distinguish solids from gases and distinguish solids from gases and liquidsliquids

OrganizationOrganization Attractive Attractive ForcesForces

SolidSolid -Orderly Orderly arrangementarrangement-Particles tightly Particles tightly packedpacked- vibrate about vibrate about fixed pointsfixed points-Not easily Not easily compressedcompressed-Crystalline Crystalline (most)(most)

-strongest-strongest

GasGas -small, hard -small, hard spheresspheres-volume not -volume not significantsignificant

-none-none-independent -independent particle particle movementmovement

LiquidLiquid -similar to gas -similar to gas but closerbut closer-flows-flows

-medium-medium-attraction to one -attraction to one another keeps another keeps liquid particles liquid particles close to each close to each otherother

Condensed states of matter

distinguish crystal from glassdistinguish crystal from glassStructureStructure AppearanceAppearance

CrystalCrystal -Arranged in orderly, Arranged in orderly, repeating, 3-D pattern repeating, 3-D pattern called Crystal Latticecalled Crystal Lattice-Shape of crystal Shape of crystal reflects arrangement reflects arrangement of the particlesof the particles-Smallest group of Smallest group of particles that retain particles that retain geometric shape of geometric shape of crystal is called Unit crystal is called Unit CellsCells

-Seven groups/crystal -Seven groups/crystal systems (Cubic, systems (Cubic, Tetragonal, Tetragonal, Orthorhombic, Orthorhombic, Monoclinic, Triclinic, Monoclinic, Triclinic, Hexagonal, Hexagonal, Rhombohedral)Rhombohedral)

GlassGlass -Lacks ordered internal -Lacks ordered internal structure/atoms structure/atoms randomly arranged randomly arranged (called amorphous (called amorphous solid)solid)

-Internal structure -Internal structure between solid and between solid and liquidliquid

-Transparent fusion -Transparent fusion product of inorganic product of inorganic substancessubstances

-”Supercooled Liquids”-”Supercooled Liquids”

sublimationsublimationThe change of a substance from a solid to a The change of a substance from a solid to a vapor without passing through the liquid statevapor without passing through the liquid state

occurs in solids with vapor pressures that exceed occurs in solids with vapor pressures that exceed atmospheric pressure at room temperature. atmospheric pressure at room temperature.

Ex. Dry iceEx. Dry ice

depositiondepositionThe change of a substance from a vapor The change of a substance from a vapor to a solid without passing through the to a solid without passing through the liquid stateliquid state

The reverse of sublimation!!!The reverse of sublimation!!!

Ex. frost on the windowsEx. frost on the windows