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States of Matter

Section 16.1

http://www.harcourtschool.com/activity/states_of_matter/

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Physical Change

IDENTITY DOES NOT CHANGE!!

– a change in size, shape, or state of matter

– All phase changes are physical changes!!

– may or may not involve energy changes and color changes

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Distillation

Separating a mixture through evaporating a liquid and re-condensing its vapor.

– Vapors from the liquid with the lowest boiling point form first and are condensed and collected

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Chemical Change

change in identity- changes the COMPOUND or SUBSTANCE

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Kinetic TheoryExplains how particles in

matter behaveAll matter is composed of

small particlesParticles are in constant

random motionParticles collide with each

other and the walls of their containers constantly

Produces pressure

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Kinetic energyTotal energy of a material’s Particlescauses the particles to vibrate KE - energy of motionLow KE in solidsHigh KE in gases

Higher temperatures- more vibration

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•Average KE = Temperature Of a substance

• or how fast the particles are moving

Lower in Solids, Higher in Liquids Highest in Gases

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Particle Motion

Only temp at which No particle motion Absolute zero 0 K (kelvin)

-273 ˚C

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SolidsParticles are closely arranged in a specific type of geometric arrangementCrystal structuredefinite shape and volume

particles have strong attraction for each other, preventing motion – held in rigid structure

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Geometric arrangement of particles in a solid- determines chemical & physical properties of a solidSolids- particles are closely packed

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MeltingDifferent solids melt in different ways: Amorphous -solid that softens and

gradually turns into a liquid over a large temperature range – don’t form crystals

Ex. Glass, rubber, cotton candy, plastic, Coal

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Crystalline solids- have set geometric structure-melt at a set temperatureWater, NaCl (table salt), Diamond, Graphite, Sugar

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Liquids

Indefinite shapeDefinite volumeTake the shape of their container

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LiquidsParticles have more space between them allowing them to Flow and take the shape of their container.Particles of a liquid have more KE than particles of a solid

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BuoyancyBuoyancyThe ability of a fluid (liquid or a gas) to The ability of a fluid (liquid or a gas) to exert an upward force on an object exert an upward force on an object immersed in it immersed in it The 2 forces acting on any object in a fluid The 2 forces acting on any object in a fluid

are Weight Force and Buoyant Forceare Weight Force and Buoyant Force

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When object FLOATSWhen object FLOATS

Buoyant force is equal to the Buoyant force is equal to the object’s weight object’s weight

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ViscosityViscosity

A Fluid’s resistance to flowA Fluid’s resistance to flow

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Viscosity is different for different fluids Viscosity is different for different fluids because structure of fluids differsbecause structure of fluids differs If moving particles don’t pull others into If moving particles don’t pull others into

motion, liquid has motion, liquid has high viscosity (slow high viscosity (slow flowing)flowing)

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If moving particles do pull others into If moving particles do pull others into motion, liquid has motion, liquid has low viscosity (flow low viscosity (flow easily)easily)

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How does Temperature affect Viscosity?

Viscosity is greater when the substance is Cold Cold particles move slower and transfer energy particles move slower and transfer energy

slowerslower Ex. Syrup that’s Cold vs. micro-waved Ex. Syrup that’s Cold vs. micro-waved

syrupsyrup

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Gas

particles have enough energy that they have escaped the attractive forces that held them in liquid state

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Indefinite volume and indefinite shape

Takes shape and volume of container

Gas

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Particle Motion - GasParticles of a gas-have enough KE to overcome the attractions between them completelySpread and fill the container completely

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Diffusion-spreading of particles throughout a container until they are uniformly distributed

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Plasma

Gas-like state of matter consisting of positive and negative particlesMost common state of matter in universe

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Changes in State of matter

• Also called phase changes.• All are physical changes!!!

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From solid to liquidin solids, particles

move slowlyHeat is added-

particles move faster

When have enough KE (moving fast enough), they overcome the attractive forces between the particles and escape the solid

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Liquid StateA solid begins to liquefy at the Melting Point- temperature at

which a solid begins to liquefy.

As the particles gain enough energy to over come their ordered arrangement

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At what temperature does water freeze?At what temperature does water melt?• The temperature at which a

substance melts Melting point, is the same as the temperature at which it freezes

• Melting pt. = Freezing pt.

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Liquid to gasSome particles of a liquid move faster than others and escape the attractive forces of other particles- allows them to enter the gas phase

Call this EvaporationCan occur below its BP

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Boiling- the Temp. at which the Pressure of a vapor in the liquid is equal to the external Pressure acting on the surface of the liquid

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Boiling pt and PressureLower external pressure like on a mountain means lower boiling point

Higher external pressure like at sea level means higher boiling point

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What is sublimation?

• When a substance skips the liquid state. • Goes straight from a solid to a gas• Ex. Dry Ice

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THERMAL EXPANSION

Increase in the size of a substance with the temperature increases.Size of substance will decrease when temp

decreasesExpansion and Contraction occur in most

Solids, Liquids and Gases

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For Example: Thermometers

energy is addedparticles of the liquid move faster & farther apartforces fluid upward through the thermometer

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Hot air balloons risehigher temperature = expansion = lower density = rises

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Analyzing Heating Curves

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Heating Curve

AB

C

D E

•A- SOLID is being heated- energy is used to increase temperature•It is still a solid, just getting hotter or colder.

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•B- Phase Change- heat of fusion - melting point – energy is used to overcome attractions b/w particles

AB

C

D E

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Heat of fusion-

the amount of energy required to change a substance from the solid phase to the liquid phase at its melting point

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C-liquid is heated up- heat energy is used to increase temperature of liquid

Substance is still a liquid only getting hotter or colder

AB

C

D E

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• D- Phase change (liq to gas- heat of vaporization- boiling point- energy is used to overcome attractions

AB

C

D E

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Heat of vaporization- amount of energy required to overcome the pressure at the surface of the liquid Liquid to a Gas Energy needed to boilPhase change from Liquid to

Vapor

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E – vapor or gas is being heated- energy is used to increase temperature of Vapor

AB

C

D E

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Water- Essential to Life on Earth!!

Has “+” and “–” regions

Decrease in temperature-particles get closer together

“-” from one particle attracts to “+” of other moleculeMost Dense at 4 °C

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Empty spaces in ice are greater than those in waterIce is less dense than water

Different from all other substances Water expands from liquid to solid!

Water

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Why might this occur??

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