Chapter 13 Lecture

Water exists on Earth as a liquid, a solid, and a vapor. As water cycles through the atmosphere, the oceans, and Earth’s crust, it undergoes repeated changes of state. You will learn what conditions can control the state of a substance.

BELLWORK-name thefollowing phase changes:a)Solid to liquid b) liquid to solidc)Liquid to gas d) gas to liquide) Solid to gas

Bellwork -State Changes

Melting - solid to liquid

Freezing- liquid to solid

Vaporization- liquid to gas

Vapor- a gas that is usually a liquid at room temp

Condensation- changing from a gas to a liquid

Chapter 13- States of MatterIntro to Gases

The skunk releases its spray! Within seconds you smell that all-too-familiar foul odor. You will discover some general characteristics of gases that help explain how odors travel through the air, even on a windless day.

The Kinetic Molecular Theory explains the behavior of gases.

13.1

The word kinetic refers to motion.

The word kinetic refers to motion.

•The energy an object has because of its motion is called kinetic energy.

The word kinetic refers to motion.

•The energy an object has because of its motion is called kinetic energy.

•According to the kinetic theory, all matter consists of tiny particles that are in constant motion.

Kinetic Molecular Theory: GASES

Kinetic Molecular Theory: GASES

•The particles in a gas are small, hard spheres with an insignificant volume.

Kinetic Molecular Theory: GASES

•The particles in a gas are small, hard spheres with an insignificant volume.

•The motion of gas particles is rapid, constant, and random.

Kinetic Molecular Theory: GASES

•The particles in a gas are small, hard spheres with an insignificant volume.

•The motion of gas particles is rapid, constant, and random.

•All collisions between gas particles are perfectly elastic (no energy lost).

Gas particles are in rapid, constant motion.

13.1

Gas particles travel in straight-line paths.

Gas particles move randomly.

13.1

A gas fills its container.

13.1

Kinetic theory explains gas pressure.13.1

Pressure = Force/AreaA force is a push or a pull.

13.1

more area

less area

more pressure!

Same force

Which would you prefer? Why?

Kinetic theory explains gas pressure.13.1

Kinetic theory explains gas pressure.13.1

Gas pressure is the force exerted by gas particles hitting the surface of an object.

Kinetic theory explains gas pressure.13.1

Gas pressure can KILL!

An empty space with no particles and no pressure is called a vacuum.

Atmospheric pressure is the pressure created by the earth’s gravitational pull on the gases in our atmosphere.

Gas pressure is exerted in all directions.

A barometer is a device that is used to measure atmospheric pressure.

An empty water bottle, closed tightly at high elevation, will be crushed by the atmosphere at sea level.

Pressure Poem

Units of Pressure

•The SI unit of pressure is the pascal (Pa).

•One standard atmosphere (atm) is the atmospheric pressure at sea level.

13.1

13.1

13.1

450 kPa x

13.1

450 kPa x kPa

13.1

450 kPa x kPaatm

13.1

450 kPa x kPaatm 1

101.3

13.1

450 kPa x kPaatm 1

101.3 = 4.4 atm

13.1

450 kPa x kPaatm 1

101.3

450 kPa x

= 4.4 atm

13.1

450 kPa x kPaatm 1

101.3

450 kPa x kPa

= 4.4 atm

13.1

450 kPa x kPaatm 1

101.3

450 kPa x kPamm Hg

= 4.4 atm

13.1

450 kPa x kPaatm 1

101.3

450 kPa x kPa760 101.3

mm Hg

= 4.4 atm

13.1

450 kPa x kPaatm 1

101.3

450 kPa x kPa760 101.3

mm Hg

= 4.4 atm

= 3400mm Hg

for Sample Problem 13.1

Particles at a given temperature have a wide range of kinetic energies. Most of the particles have kinetic energies in the middle of this range.

Particles at a given temperature have a wide range of kinetic energies. Most of the particles have kinetic energies in the middle of this range.

Particles at a given temperature have a wide range of kinetic energies. Most of the particles have kinetic energies in the middle of this range.

Temperature measures Average Kinetic Energy

The Kelvin temperature of a substance is directly proportional to average kinetic energy.

13.1

The Kelvin temperature of a substance is directly proportional to average kinetic energy.

13.1

The higher the kinetic energy, the higher the temperature.

Two substances with the same average kinetic energy are at the same temperature.

Two substances at the same temperature have the same average kinetic energy.

13.1

Absolute zero (0 K, or –273.15°C) is the temperature at which the motion of particles theoretically stops.

13.1

Absolute zero (0 K, or –273.15°C) is the temperature at which the motion of particles theoretically stops.

•Particles would have no kinetic energy at absolute zero.

13.1

Absolute zero (0 K, or –273.15°C) is the temperature at which the motion of particles theoretically stops.

•Particles would have no kinetic energy at absolute zero.

•Absolute zero has never been produced in the laboratory (and not for lack of trying!).

13.1

Bellwork- Kinetic Energy

•What is kinetic energy?•How is average kinetic energy related to temperature?•Which has higher kinetic energy, an olympic size pool of water or a cup of hot coffee?

Substances that can flow are referred to as fluids. Both liquids and gases are fluids.

13.2

The intermolecular attractions (IMFs) are counteracted by motion of molecules. Together they determine the physical properties of liquids.

High IMFs promote a solid state

High temps (motion) promote a gas state.

13.2

13.2

If the liquid is not boiling it is called evaporation.

When a liquid converts to a gas it is called

vaporization.

13.2

If the liquid is not boiling it is called evaporation.

When a liquid converts to a gas it is called

vaporization.

13.2

If the liquid is not boiling it is called evaporation.

When a liquid converts to a gas it is called

vaporization.

13.2

If the liquid is not boiling it is called evaporation.

In a closed container, evaporated molecules collect as a vapor above any liquid.Vapor pressure is the force exerted by a gas above a liquid.

13.2

During evaporation, only molecules with a certain minimum kinetic energy can escape from the surface of the liquid.

During evaporation, only molecules with a certain minimum kinetic energy can escape from the surface of the liquid.

During evaporation, only molecules with a certain minimum kinetic energy can escape from the surface of the liquid.

Evaporation is a cooling process because the molecules with the highest kinetic energy escape.

13.2

In an open container, molecules that evaporate can escape from the container.

Some evaporated molecules will condense back into a liquid.

Some evaporated molecules will condense back into a liquid.

Some evaporated molecules will condense back into a liquid.

A dynamic equilibrium exists between the vapor and the liquid.

The system is in equilibrium when the rate of evaporation equals the rate of condensation.

DYNAMIC EQUILIBRIUM

DYNAMIC EQUILIBRIUM

For each molecule that evaporates a different molecule returns to the liquid.

DYNAMIC EQUILIBRIUM

For each molecule that evaporates a different molecule returns to the liquid.

SAME RATES!!

DYNAMIC EQUILIBRIUM

DYNAMIC EQUILIBRIUMEquilibrium- The amount of liquid and vapor do not change.

DYNAMIC EQUILIBRIUMEquilibrium- The amount of liquid and vapor do not change.Dynamic- There is a constant turnover of particles.

Vapor pressure increases with Temperature.

13.2

The particles have increased kinetic energy, so more particles will have the minimum energy needed to escape the liquid.

When a liquid is heated to a temperature at which particles throughout the liquid have enough kinetic energy to vaporize, the liquid begins to boil.

Liquids boil when their vapor pressure exceeds the pressure pushing down on the liquid (usually atmospheric pressure).

13.2

Boiling Point and Pressure Changes

Boiling Point and Pressure ChangesBecause a liquid boils when its vapor pressure is equal to the external pressure, liquids don’t always boil at the same temperature.

Boiling Point and Pressure ChangesBecause a liquid boils when its vapor pressure is equal to the external pressure, liquids don’t always boil at the same temperature.

•At high altitudes, atmospheric

pressure is low, so water boils cooler and food needs longer to cook.

Boiling Point and Pressure ChangesBecause a liquid boils when its vapor pressure is equal to the external pressure, liquids don’t always boil at the same temperature.

•At high altitudes, atmospheric

pressure is low, so water boils cooler and food needs longer to cook.

• A pressure cooker increases the

boiling point so food cooks fast.

Altitude and Boiling Point

The normal boiling point is the boiling point of a liquid at atmospheric pressure (1 atm or 101.3 kPa)

Section 13.3- Solids

Solids keep their shape because their particles are in fixed positions.

In a crystalline solid, the particles are in an orderly, repeating, three-dimensional pattern called a crystal lattice.

elemental metalionic compound

When an element can make more than one structure, the different forms are called allotropes.

13.3

When an element can make more than one structure, the different forms are called allotropes.

•Allotropes have different properties because their structures are different.

13.3

When an element can make more than one structure, the different forms are called allotropes.

•Allotropes have different properties because their structures are different.

•Only a few elements have allotropes.

13.3

Carbon’s allotropes are diamond and graphite

13.3

Non-Crystalline SolidsAn amorphous solid lacks an ordered internal structure.•Rubber, plastic, asphalt, and glass are amorphous solids.

Non-Crystalline SolidsAn amorphous solid lacks an ordered internal structure.•Rubber, plastic, asphalt, and glass are amorphous solids.

Quartz is crystallized SiO2 Glass is amorphous SiO2

Non-Crystalline Solids

Quartz is crystallized SiO2 Glass is amorphous SiO2

Non-Crystalline SolidsAn amorphous solid lacks an ordered internal structure.

Quartz is crystallized SiO2 Glass is amorphous SiO2

Non-Crystalline SolidsAn amorphous solid lacks an ordered internal structure.•A glass has cooled to a rigid state without crystallizing.

Quartz is crystallized SiO2 Glass is amorphous SiO2

13.4

The change of a substance from a solid to a vapor without passing through the liquid state is called sublimation.

Sublimation occurs in solids with vapor pressures that exceed atmospheric pressure at or near room temperature.

13.4

The change of a substance from a solid to a vapor without passing through the liquid state is called sublimation.

Sublimation occurs in solids with vapor pressures that exceed atmospheric pressure at or near room temperature.

13.4