Using Energy & Heat

Kinetic Molecular Theory All Matter is Made of Particles Particles are in Constant, Random Motion  These particles possess kinetic energy  Their motion increases as energy increases Particles Constantly Collide with each other and with the Walls of their Container.

Temperature The measure of average kinetic energy of the particles in a material Temperature is measured: SI Unit – (K)elvin K = C (10C = 283K) (C)elsius C = K – 273 (10K = -263C) (F)ahrenheit

Thermal Expansion

Most materials expand when heated Liquid thermometers based on mercury or alcohol expansion are common When particles are cool they move slowly, and take up less volume When particles are hot they move faster, and take up more volume When particles cool down they contract. How thermostats work:

Thermal Energy The total kinetic and potential energy of all particles in a substance. Depends on temperature, mass, and type of substance. As temperature increases, so does thermal energy (because the kinetic energy of the particles increased). Even if the temperature doesn’t change, the thermal energy in a more massive substance is higher (because it is a total measure of energy). 200 mL 80ºC A 400 mL 80ºC B

Heat The flow of thermal energy from one object to another. Heat always flows from warmer to cooler objects. Ice gets warmer while hand gets cooler Cup gets cooler while hand gets warmer

Thermal Equilibrium Is obtained when touching objects within a system reach the same temperature.

Heat Transfer Energy can be transferred 3 Main ways: Conduction Convection Radiation

Transferring Thermal Energy: Conduction Conduction Conduction – transfer of heat from one substance to another through direct contact, collision of particles (transfer of thermal energy by collisions b/w particles in matter.)

Transferring Thermal Energy: Convection ConvectionConvection –transfer of energy as heat by the movement of fluid (liquid) & air, movement of particles from a material to another. (transfer of thermal energy by the movement of particles from one part of a material to another) When fluid is heated, it expands, becomes less dense, and rises.

Transferring Thermal Energy: Radiation RadiationRadiation – the transfer of energy by electromagnetic waves When radiation is emitted from one object and then absorbed by another, the result is the transfer of heat. Radiation can travel through empty space.

13 Heat is the transfer of Thermal energy by Conduction ConvectionRadiation

Examples of Energy Transfers

Heat and Changes of State Change of state-physical change from one state to another depends on thermal energy and……. particle arrangement energy of particles distance between particles

STATES OF MATTER SOLID LIQUID GAS PLASMA Tightly packed, in a regular pattern Vibrate, but do not move from place to place Close together with no regular arrangement. Vibrate, move about, and slide past each other Well separated with no regular arrangement. Vibrate and move freely at high speeds Has no definite volume or shape and is composed of electrical charged particles

PHASE CHANGE S Description of Phase Change Term for Phase Change Heat Movement During Phase Change Solid to liquidMelting Heat goes into the solid as it melts. Liquid to solidFreezing Heat leaves the liquid as it freezes. Liquid to gas Vaporization, which includes boiling and evaporation Heat goes into the liquid as it vaporizes. Gas to liquidCondensation Heat leaves the gas as it condenses. Solid to gasSublimation Heat goes into the solid as it sublimates. Gas to SolidDeposition Heat leaves water vapor as it deposits into a solid

FYI: Bose Einstein Condensate They are super unexcited and super cold atoms. The BEC happens at super low temperatures. At zero Kelvin (absolute zero) all molecular motion stops. Atoms begin to clump. They lose almost all their energy There are no longer 1000’s of separate atoms. They all take the same qualities and become one big blob “Super Atom.” Only a very few special elements have been able to attain temperatures a billionth above absolute zero. Rubidium being one of them.