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Kinetic Energy, Temperature, Phase Changes Chapter 13 Concepts.

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Presentation on theme: "Kinetic Energy, Temperature, Phase Changes Chapter 13 Concepts."— Presentation transcript:

1 Kinetic Energy, Temperature, Phase Changes Chapter 13 Concepts

2 Kinetic Energy particles have a wide range of K.E. use the average kinetic energy of all particles substances in different states of matter can have the same average K.E. –table salt, water, helium at room temperature the Kelvin temp. of a substance is directly proportional to the average K.E. of the particles in a substance –200 K has twice as much K.E. as 100 K


4 Temperature vs. Heat temperature is a measure of the average kinetic energy in a system heat is the energy transfer between two systems


6 Absolute Zero particles would stop moving at a very low temperature zero Kelvin is the temperature where motion of particles theoreticaly ceases closest we have come is 0.5 x 10 –9 K


8 Phase Changes

9 LIQUID GAS SOLID melting vaporization* *evaporation *boiling sublimation condensation freezing or solidification = taking away heat (cooling down) = adding heat (heating up)

10 Vapor Pressure measure of the force exerted by a gas above a liquid dynamic equilibrium is reached when condensation equals evaporation

11 an increase in temperature increases the vapor pressure of the liquid molecules have increased KE –more molecules will “escape”


13 Evaporation a type of vaporization – the conversion of a liquid to a gas or vapor evaporation is vaporization at the surface only molecules with a certain amount of KE can escape from the surface

14 particles left behind have a lower KE thus, evaporation is a “cooling process” think of what happens when you sweat

15 Boiling Point a type of vaporization where the vapor pressure of liquid is equal (to the external pressure on the liquid (atmospheric pressure) when a liquid is heated to a temperature at which particles throughout the liquid have enough KE to vaporize


17 Boiling point and pressure BP will change due to vapor pressure different elevations will result in different BP normal BP is at STP (101.3 kPa) Why must you cook things longer at higher elevations?

18 Melting Point temperature at which a solid changes into a liquid disruptive vibrations overcome attractive forces holding particles together

19 Sublimation change from solid directly to liquid when solid’s vapor pressure exceeds atmospheric pressure at room temperature example: iodine, dry ice, air fresheners, freeze dried coffee

20 Condensation conversion of a gas to a liquid molecules with lower KE go back into liquid form

21 Freezing or Solidification process in which a liquid turns into a solid when cold enough most liquids freeze by crystallization for most liquids, the freezing point and melting point are the same temperature


23 Phase Diagrams provides conditions of pressure and temperature at which a substance can exist as a solid, liquid, and vapor the triple point is where all three phases exist at once


25 Review of Concepts


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