Changes of State

Matter mostly exists is one

of three states or phases:

solid, liquid or gas.

An increase or decrease in

energy (temperature) can lead to a

change of phase.

Sublimation (Deposition): Change from gas directly to a solid or from a solid directly to a gas.

Types of Changes of State

SOLID LIQUIDGAS

Melting: Change from solid to

liquid.

Vaporization/Evaporation: Change from liquid to gas.

Solidification/Crystallization

(freezing): Change from liquid to solid.

Condensation: Change from gas to liquid.

Stored Heat and Changes of State

When an object is in one of the three states, its temperature rises as thermal energy is

added to it.

If an object is in the process of changing its state of matter, the temperature

remains the same as thermal energy is

added to it.

When an object is in one of the three states, its temperature rises as thermal energy is

added to it.

SOLID BASALT LIQUID BASALT

THERMAL ENERGY THERMAL ENERGY

Temperature rises

Temperature rises

Melting/Solidification

Stored Heat and

Changes of State

When an object is changing phase, the thermal energy added to it does not increase the temperature of the object.

The added thermal energy becomes a form of stored or potential energy. This is also known as latent heat.

SOLID BASALT LIQUID BASALT

THERMAL ENERGY THERMAL ENERGY

Melting/Solidification

In order for an object to change phase from: solid liquid gas

The object GAINS stored HEAT ENERGY

In order for an object to change phase from:gas liquidsolid

The object MUST RELEASE its stored HEAT ENERGY

What happens to the thermal energy of the

solid basalt when it melts?

When the basalt melts the thermal energy will not

raise the temperature of the rock. Instead the rock

will gain stored heat energy.

Stored Heat and Changes of State of Water

Gain Heat Energy

Lose Heat Energy

How long did it take for the water sample to

boil?

4 minutes.

How long was the change of state for the water sample from liquid to gas (vapor)?

4 minutes

What happens to the heat energy added to the water sample after 4

minutes into the experiment?

The added heat energy did not change the temperature of the

water. Heat energy was absorbed and stored as the water changed

state from liquid to gas.

Stored Heat and Changes of State of Water Heat gained during

vaporization: 2260 J/g

Heat released during condensation: 2260 J/g

Heat released during freezing: 334 J/g

Heat gained during melting: 334 J/g

RT = Pg. 1

Earth’s Energy Supply: Solar Energy

The majority of Earth’s energy comes from the Sun.

The sun “radiates” all forms of electromagnetic energy including visible light (greatest intensity).

NOTE** Deuterium and Tritium are two forms of hydrogen.

Solar energy is a product of nuclear fusion. In nuclear fusion, two light elements (hydrogen) are

combined to form one heavier element (helium) under

tremendous amounts of heat and pressure.

The process of nuclear fusion produces a great amount of energy

– including the electromagnetic energy that is radiated to Earth.

Earth’s Energy Supply: Earth’s Interior Some of Earth’s energy comes from the planet itself.

Heat from the Earth can be changed to kinetic energy as

mountains are made and volcanoes erupt.

The Earth still is generating heat from its own creation some 4.5 billion years ago

(Earth’s core). The core is the source of gravity for the planet. Materials being pulled towards

the center of the Earth generate energy.

Most energy created in Earth’s interior is from nuclear decay

or nuclear fission.

Nuclear fission is the opposite of nuclear fusion. In nuclear fission a heavier, unstable element (uranium) “decays” or is broken down into two lighter elements (rubidium and cesium). This process releases a large

amount of energy.

Today’s nuclear reactors use this same process as an alternative energy source to the burning of fossil fuels.