The universe is made up of:The system – the thing that you are studyingThe surroundings- everything else

Energy – the ability to do work Potential energy – stored energy

(determined by the arrangement of the molecules)

Kinetic energy – energy of motion Thermal Energy - determined by the

movement of the molecules (KE) and the arrangement of molecules (PE); sum of all the energy in a sample of matter.

http://www.empowernetwork.com/jay4biz/blog/market-temperatures/thermometer2/

measures the average

kinetic energy of particles

What is heat??

The transfer of thermal energy.

Measured in:joules (J)kilojoules (kJ)calories (cal)kilocalories (kcal)

http://www.neatorama.com/spotlight/2010/02/13/7-mad-science-experiments-you-can-do-at-home-but-probably-shouldnt/

Heat always flows from areas of high temperature to low temperature.

http://www.aos.wisc.edu/~aalopez/aos101/wk5.html

Is reached when two objects or systems reach the same temperature and stop exchanging energy through heat.

three types of heat transfer:•Conduction•Convection•Radiation

http://faculty.icc.edu/easc111lab/labs/labi/prelab_i.html

The transfer of heat through direct contact (solid to solid or solid to liquid).

http://faculty.icc.edu/easc111lab/labs/labi/prelab_i.html

The transfer of heat involving fluids (liquids or gases) through currents.

http://hendrix2.uoregon.edu/~imamura/102/section3/chapter16.html

The transfer of heat that does not involve a medium; can occur in a vacuum (Ex. Sun)

http://faculty.icc.edu/easc111lab/labs/labi/prelab_i.html

http://news.discovery.com/space/private-spaceflight/mars-bound-rover-feels-the-wrath-of-suns-radiation-120130.htm

Melting/Freezing Changes between solid and liquid phases

Vaporization/Condensation Changes between liquid and gas phases

Sublimation/Deposition Changes directly between solid and gas

phases

Endothermic phase changes absorb energy Sublimation Vaporization Melting

Exothermic phase changes release energy Deposition Condensation Freezing

Vaporization- The process of changing from a liquid to a gas. When this occurs

only at the surface, the process is called evaporation.

Evaporation is how our body controls its temperature. For sweat to evaporate, energy is required. This energy comes from your body. This loss of energy leaves us feeling cooler.

As temperature increases the amount of evaporation increases.

If evaporation is taking place in a closed container, the evaporated particles exist as a vapor

Vapor Pressure is the pressure exerted by vapors above a liquid in dynamic equilibrium Dynamic equilibrium occurs when 2

opposite processes occurr at the same rate▪ Ex: evaporation and condensation

Vapor pressure depends on… Temperature (T V.P.) Strength of IMF (IMF V.P.)

Volatile refers to how easily a fluidevaporates (high vapor pressure)

Vapor

Water Alcohol

Vapor

Intermolecular forces act between stable particles

Weak intermolecular forces Low boiling points Most likely in gaseous state

Strong intermolecular forces High boiling points Most likely in solid state

show how a substance’s temperature changes as energy is added or removed

During phase changes, there is no change in kinetic energy - only potential energy increases!!!

The KE only changes when the temp changes. Liquid H2O at 0oC has more total energy than solid H2O at 0oC

Gas H2O at 100oC has more total energy than liquid H2O at 100oC

Temperature and pressure control the phase of a substance.

A phase diagram is a graph of pressure versus temperature that shows in which phase a substance exists under different conditions of temperature and pressure.

• A phase diagram has three regions, each a different phase and three curves that separate each phase.

Sublimation point

Freezing point

Boiling point

• The points on the curves indicate conditions under which two phases coexist.

The triple point is the temperature and pressure at which three phases of a substance can coexist. All six phase changes can

occur at the triple point: The critical point is the

pressure and temperature above which a substance cannot exist as a liquid.

Standard Pressure Line (1 atm)

Normal Freezing Point Temp at which

standard pressure meets the solid-liquid curve

Normal Boiling Point Temp at which

standard pressure meets the liquid-vapor curve

Normal Boiling Point

Normal Freezing Point

STP

Compare the normal BP and FP of H2O and CO2

What is different about the 2 types of diagrams?

Q: Why does water boil at a lower temperature at higher altitudes?

A: Pressure is lower, meaning less energy required to overcome intermolecular forces (less forces “holding it together”)

The specific heat of any substance is the amount of heat required to raise the temperature of one gram of that substance one degree Celsius. Each substance has its own specific heat Determined by different composition/arrangement of

particles

Why will the Why will the metal chairs at metal chairs at the pool get hot, the pool get hot, while the water while the water stays cool?stays cool?

Water has an extremely high specific heat (4.184 J/goC)

Metals have low specific heats (<1 J/goC)