Chapter 3 States of Matter

Section 1

Matter and Energy

Kinetic Theory of Matter

• Matter is made of atoms and molecules.• Atoms and molecules act like tiny

particles.• They are always in motion.

• The higher the temperature of the substance, the faster the particles move.

• At the same temperature, the more massive particles move slower that the less massive ones.

• Example: hot tea cooking

States of Matter

• The state of matter is the physical form of the matter.

• This form is determined partly by how the substance’s particles move.

• Matter can be classified by determining whether the shape and volume are definite or variable.

• Most matter found on Earth is either a solid, liquid, or gas.

States of Matter

• Solid• Liquid• Gas• Plasma• Bose-Einsteinium condensate

Solids

• Particles vibrate in place (Brownian movement)

• Structure of solids are rigid and cannot easily change shape.

• Particles are held closely together by strong attractions which between the particles which cause solids to have a definite shape and volume.

Liquid

• Particles are closely packed but can slide past one another and move more rapidly than in a solid in order to overcome attractive force.

• Liquids flow freely (is a fluid)• Take the shape of the container• Do not change volume.• Particles are close together and in

contact.

Gas

• Particles are in constant motion.• Do not usually stick together• Change volume and shape• Are fluids because they can flow.• Are usually compressed (pushed together)• Gases expand to fill the empty space.• Example: perfume

Plasma• Most common state (99% of matter)• No definite shape or volume• No definite shape or volume• Particles are electrically charged (ionized)• Conducts electric current• Examples: in lightning, fire, aurora

borealis, sun, other stars, artifically in fluorescent lights

Kinetic energy• Energy of motion• Energy- ability to do work; ability to

change or move matter• Since all matter is made up of tiny

particles, (atoms, molecules) that are constantly in motion, all matter has kinetic energy.

Temperature• Measure of average kinetic energy of

particles in an object.• Particles of matter are constantly moving.• Do not move at the same speed.• Some particles have more kinetic energy

than others.• The higher the temperature, the more

kinetic energy.

Thermal Energy

• Depends on particle speed and number of particles.

• Does not depend on amount of substance• Thermal energy= total kinetic energy of

particles making up the substance• Total kinetic energy depends on the

number of the particles as well as the speed of particles.

Section 2 Changes of State

• The identity of substance does not change during a change of state

• The energy of a substance does change• Add energy particles move faster• Remove energy particles slow down

• Heat and energy can cause changes of state

Melting

• Heat solid, transfer energy to particles, thus they vibrate faster as they gain energy.

• They break their fixed position and melt.

• Melting point=the temperature at which a substance changes from a solid to a liquid.

• Melting point depends on pressure.

Evaporation

• Change of a substance from a liquid to gas

• Boiling is evaporation occurring throughout a liquid at a certain temperature and pressure.

• Boiling point= the temperature at which a liquid boils.

• A decrease in pressure lowers the boiling point

Sublimation

• Solid changing directly to a gas without going through the liquid state.

• Example: dry ice

• Melting, evaporation, sublimation all require energy.

Condensation

• Change of state from a gas to a liquid• Energy is released because gas particles

clump together and they slow down.• Example: breathing on a cold day

• Condensation point=the temperature at which a gas becomes a liquid

• Example: drops of water on a cold glass of a liquid

Freezing Point

• Temperature at which a liquid changes to a solid• Energy is released.• FREEZING AND MELTING OCCUR AT THE

SAME TEMPERATURE!• Water freezes at the same temperature at which

it melts. O degrees Celsius• For freezing to occur, the attractions between

the particles must be greater than their motion.• Ex: Ammonia=-77.7oC and Magnesium=650oC

Temperature

• Temperature is constant during change of state.

• When a substance loses or gains energy, its temperature changes or its state changes.

Temperature (continued)

• Temperature does not change during a change of state.

• Example: If we add energy to ice at O degrees C, the temperature will NOT rise until all of the ice has melted.

Conservation of Mass and Energy

• Mass is conserved for all physical and chemical changes.

• Energy can change forms but the total amount of energy before and after a change is the same.

• The amount of energy in a substance can change but it must come from somewhere else.

Law of Conservation of Matter and Energy

• Matter and energy are both conserved.

• Neither matter or energy can be created or destroyed.

Law of Conservation of Mass

• Mass can not be created or destroyed.• Mass before change= Mass after change

• Mass of reactants = mass of products• Match + oxygen = ash, smoke, gases

Law of Conservation of Energy

• Energy can not be created or destroyed.

Energy before change =energy after change

Section 3 Fluids

• Liquids and gases are fluids.

• Fluids exert pressure evenly in all directions.

• Pressure= amount of force exerted on a given area of surface.

• Example: air up bicycle tire

Pressure

• P=F/A

• Pressure = force divided by area

• Unit of pressure is Pascal

• SI unit of force is the newton.

• One Pascal=force of 1 newton exerted over an area of 1 square meter or 1N/m2

Buoyant Force

• A buoyant force pushes a duck up if you push a duck down.

• All fluids exert an upward buoyant force.

Archimedes’ Principle

• Used to find buoyant force

• The buoyant force on an object in a fluid is an upward force equal to the weight of the fluid that the object displaces.

• You can determine if an object will float or sink by comparing the buoyant force on the object with the object’s weight.

• See example of sea gull on page 90

Density

• Can determine if an object will float or sink by comparing densities.

• More dense objects sink.

• Ex: Helium less dense than air so it floats.• Steel is almost 8 times denser than water.

Density (continued)

• Ships float and carry cargo and still float.• Shape is the answer. Boats have a hollow

hull. The hollow shape of the boat allows it to have the same amount of steel but the density is decreased by the hollow shape. Water is then denser than the boat and the boat floats.

Pascal’s Principle

• A change in pressure at any point in an enclosed fluid will be transmitted equally to all parts of the fluid.

• Ex: toothpaste tube

• If the pressure in a container is increased at any point, the pressure increases at all points by the same amount.

Pascal’s Principle (continued)

• P1=P2 because P=F/A or

• F1/A1 = F2/A2

• Hydraulic devices use this principle.

• Hydraulic devices use liquids to transmit pressure form 1 point to another. Liquids can not be compressed into a much smaller space.

continued

• Hydraulic devices multiply forces.• Fluid is usually oil.

Fluids in Motion

• Fluids move faster through small areas than through larger areas, if the overall flow rate remains constant. (garden hose)

• Fluids also vary in the rate at which they flow.

Viscosity

• Viscosity- a liquid’s resistance to flow.

• The stronger the attraction between a liquid’s particles, the more viscous the liquid is. Ex: Honey, water

Bernoulli’s Principle

• States that as the speed of a moving fluid increases, the pressure of the moving fluid decreases.

• See example of leaf on page 94

Section 4 Behavior of Gases

• Fluids• Move rapidly in all directions• Expand to fill containers they are in• Spread out easily• Mix with one another• Low density• Are compressible• Mostly empty space

Gases and Pressure

• Gases under pressure are dangerous.

• Gases under pressure rush out if given an escape route. (balloon)

• Must be handled very carefully.

Gas Laws

• Volume of a gas is the same as the volume of the container it is in

• Gases behave differently than solids and liquids.

• Gas laws describe how the behavior of a gas in affected by pressure, volume, and temperature.

• Can use gas laws to predict the behavior of gases in specific situations.

Boyle’s Law

• Relates pressure of a gas to its volume

• For a fixed amount of gas at a constant temperature, the volume of a gas increases as the gas’s pressure decreases.

• Also, the volume of a gas decreases as the gas’s pressure increases.

• Temperature does not change.• One increases when the other decreases.

Boyle’s Law (continued)

• Pressure1(volume1)=Pressure2(volume2)

or

P1V1 = P2V2

1 is initial volume and pressure and 2 is final

volume and pressure

Gay-Lussac’s Law

• Relates gas pressure to temperature at constant volume

• Pressure= result of collision of gas molecules against wall of container

• Temperature increases, motion of particles increases meaning kinetic energy increases meaning energy and frequency of collisions increases.

Gay-Lussac’s Law (continued)

• For a fixed quantity of gas at constant volume, the pressure as the temperature increases.

• The pressure of a gas increases as the temperature increases, if the volume of the gas does not change. The pressure decreases as the temperature decreases.

• Example: tires in cold weather lose air???• Pressurized containers like hair spray

Charles’ Law

• Relates temperature to volume

• For a fixed amount of gas at a constant pressure, the volume of the gas increases as the gas’s temperature increases and the volume of the gas decreases as the gas’s temperature decreases.

• Example: balloon in heat, balloon in cold