States of MatterSolid

Lowest energy/heatMolecules barely movingDefinite, uniform shapeExample: ice

States of MatterLiquid

Medium energy/heat Molecules slowly movingShape of containerExample: water

States of MatterGas

High energyMolecules moving rapidly and bouncingFills its containerExample: steam

© UC Regents http://ds9.ssl.berkeley.edu/LWS_GEMS/2/part2.htm

Phase Changes

Phase Changes

• Solid liquid

• Liquid gas

• Solid gas

• Gas liquid

• Liquid solid

• Gas solid

melting

boiling, evaporation

sublimation

condensation

freezing

deposition

Phase Changes

Condensation

Evaporation

Melting

Freezing

SublimationDeposition

GAS

LIQUIDSOLID

When a solid is heated…The temperature increases

UNTIL

It reaches it’s melting point

THEN it turns to a liquid at that temperature

The temperature will not change unless all matter

is in the same stateIce will warm, then melt, the liquid will warm

It takes energy for those molecules to change state!

Heating/Cooling Curve

Heat of Vaporization

Heat of Fusion/Crystallization

Energy is added as Heat

Heating CurvesEnergy is added to the system at a constant rate

Temperature increases at a constant rate UNLESS it is changing phase

PhasesThe phase of a substance depends on:

TEMPERATURE PRESSURE

Phase diagram

The phase diagram is graph of pressure vs. temperature that shows conditions under which the phases of a substance exist

If you know T and P, you can figure out the state!

http://itl.chem.ufl.edu/4411/2041/lec_f.html

Triple Point: Unique temperature and pressure where all three phases exist…AT THE SAME TIME!!!

Phase Diagrams for Water and CO2

*Atmospheric Pressure is 1.0 atm

Phase Diagram WorksheetTry answering the questions about the mystery

substance!

Phase ChangesA heating curve shows a substance’s change in

temperature while adding heat energy

Heating Curve ws

Changes in Matter and EnergyMatter cannot be created or destroyed.

But it can be changed and when it does, that is how we get energy!

Energy - capacity to do work or produce heatEnergy is always involved in physical and chemical changes. Energy can take several forms: Heat, light, (sound, chemical,

electrical)Measured in calories, Calories (kcal), and joules

Law of Conservation of Energy: energy can be absorbed or released, but it cannot be created or destroyed through ordinary chemical reactions.

Energy can be transferred.

Kinetic and Potential EnergyKinetic energy: is the energy of motion.

Potential Energy: energy of Position

Stored energy (chemical bonds)

Since energy is constant and cannot be created or destroyed ….Total Energy = KE + PE

Temperature: kinetic energy of all particles within matter.

There are times during phase changes when temperature does not change, but stays constant while the energy works to change the phase (ie: the heating curve of water)

Heating/Cooling Curve

Heat of Vaporization

Heat of Fusion

Energy is added as Heat

Exothermicenergy is released by the substance into the surroundings less PE, more KE, so temperature risesEx: a match burning

Endothermic energy is absorbed by the substance from the surroundingsmore PE, less KE, so temperature dropsEx: water freezing

EnergyCalorie (cal): the amount of energy (heat) required to raise

the temperature of one gram of water by one Celcius degree

Standard unit for energy is the joule (J)

1 cal = 4.184 J

60.1 cal x 4.184 J = 251 J 1 cal

Specific Heat (s) : amount of energy required to change the temperature of one gram of a substance 1 oC

Varies from one substance to another

Heat always travels from high concentration to low concentration!!

Heat lost = Heat gained

Water has a specific heat = 1 cal/goC or 4.184 J/goCWater has the second highest specific heat capacity of all known

substances. So it requires high amounts of heat energy to raise water temperature.

water also has a high energy/heat requirement for evaporation

SIRON = 0.449 J/goCWhich would heat up faster, 5.00 grams of iron or 5.00 grams of

water?   Which would cool down faster, 5.00 grams of iron or 5.00 grams

of water?  Which is a better thermal conductor?  Which is a better insulator?

Q = s x m x TQ = energy (heat) required (J) or (cal)

s = specific heat capacity (J/goC) or (cal/goC)

m = mass of the sample in grams

T = change in temperature in oC

A 2.8 g sample of a pure metal requires 10.1 J of energy to change its temperature from 21 oC to 36 oC. What is the specific heat of the metal?

s = Q = 10.1 J = 0.24 J/goC m x T (2.8 g x 15oC)