Changes of State

GPS

• Element: S8P1.c Describe the movement of particles in solids, liquids, gases, and plasma states.

• S8P1.g Identify and demonstrate the Law of Conservation of Matter.  

EQ

• How does ice compare to water and water vapor?

• How does movement of particles relate to states of matter?

• How can we prove matter is neither created nor destroyed?

Energy and Changes of State

• Change of state is the change of a substance from one physical form to another.

• The particles move differently depending on the state of the substance.

• The particles also have a different amount of energy when the substance is in different states.

• Which has more energy: liquid water or ice? Steam?

• In order to change a substance from one state to another, you must add or remove energy.

Kinetic Theory of Matter:

Molecules are always moving. This is known as the kinetic theory of matter.

Molecules move due to a temperature increase or decrease

We measure this kinetic energy with a thermometer as temperature.

The greater the material's internal energy, the higher the temperature of that material.

Heat is the energy flow between objects of different temperature.

Heat and temperature are NOT the same.

Solids

Liquids

Gases4

STATES OF MATTER

Plasma

States of Matter

•The Four States of Matter

• Basis of Classification of the Four Types

Based upon particle arrangementBased upon energy of particlesBased upon distance between

particles

Solids

• Particles of solids are tightly packed, vibrating about a fixed position.

• Solids have a definite shape and a definite volume.

Liquids

• Particles of liquids are tightly packed, but are far enough apart to slide over one another.

• Liquids have an indefinite shape and a definite volume.

Gases• Particles of gases are very far

apart and move freely. • Gases have an indefinite shape

and an indefinite volume. • Gases have no free surfaces.

Plasma

Plasma is an ionized gas.

Good conductor of electricity and is affected by magnetic fields. (electrically charged) Plasma, like gases have anindefinite shape and an indefinite volume.

Most abundent...

Phase

Particle Properties

Proximity Energy Motion Volume Shape

Solid

Liquid

Gas

close little vibrational definite definite

close moderate rotational definite indefinite

far apart a lot translational indefinite indefinite

Phase ChangesMelting: Solid to Liquid

• Add energy to a solid increases the temperature which makes the particles of the solid move faster. At a certain temperature, the solid begins to melt.

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

• Different substances have different melting points.

• Endothermic: adding energy

Freezing: Liquid to Solid

• Temperature at which a liquid changes into a solid is the liquid’s freezing point.

• Freezing is the reverse process of melting, therefore, freezing and melting occur at the same temperature.

• Energy is removed (exothermic) causing the particles to become locked in place.

Evaporation: Liquid to Gas

a. Particles in a liquid gain kinetic energy.

b. They leave as gas particles (taking the energy away with them).

c. This leaves less energy in the liquid, therefore cooling down what is left

Boiling

• Change of a liquid to a vapor or gas throughout the liquid.

• Occurs when the pressure inside the bubbles equals the outside pressure on the bubbles.

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

• Amount of substance does not change the boiling point nor the melting point of a substance change.

Pressure and Boiling Point

• Water boils at 1000C only at sea level because of atmospheric pressure.

• Atmospheric pressure is lower at higher elevations so the boiling temperature is lower.

Condensation: Gas to Liquid

• Reverse of evaporation• Condensation point is the temperature at

which the gas becomes a liquid. • Condensation point is the same

temperature as the boiling point at a given pressure.

• Energy is removed and particles slow down and clump together.

• Exothermic change.

Sublimation: Solid to Gas

• Gain energy -> endothermic

Change of Temperature vs. Change of State

• Temperature is related to the speed of a substance’s particles.

• Temperature does not change until the change of state is complete. (see fig. 7 pg.79)

Phase Change Diagram

Particle PropertiesPhase Proximity Energy Motion Volume Shape

Solid Close Little Vibrational Definite Definite

Liquid Close Moderate Rotational Definite Not Definite

Gases Far apart A lot Transitional Not

definite

Not

Definite

• The Law of Conservation of Matter states that matter is cannot be destroyed or created in ordinary chemical or physical changes.