Ch 04.5: Physical Changes

Ch 04.5: Physical Changes
By the end of this lesson, you will be able to:
1. Define physical change, and give examples of physical change.

2. Explain how physical changes can be reversed.
3. Define change of state.

4. Identify processes that cause changes of state.

5. Explain the role of energy in changes of state.

Multiple Choice

A change in which the shape, size, physical state, and appearance of a substance are altered, but not its chemical composition, is called a physical change.

• true

• false

Physical Change

- a change in one or more physical properties of matter without any change in chemical properties
- the substances that make up matter are exactly the same before and after a physical change

Multiple Choice

Matter does not change into another substance during a physical change.

• true

• false

Multiple Choice

When nails, screws, and bolts are prepared from a piece of iron, the composition of iron will change.

• true

• false

Multiple Select

Which of the following is an example of physical change?

• burning

• bending

• dissolving

• rusting

Multiple Select

Which of the following is an example of physical change?

• cutting

• rotting

• stretching

• rusting

examples of a physical change include:

- change in size
- change in shape

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- cutting

- bending

- stretching

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- dissolving - when one substance mixes evenly in another substance

Change of State

- occurs whenever matter changes from one state to another

- is a physical change

Multiple Select

Which of the following is a change of state?

• liquid to solid

• gas to solid

• gas to liquid

• solid to gas

• solid to liquid

Multiple Choice

Which of the following processes is an example of a change of state?

• evaporating

• tarnishing

• combusting

• dissolving

examples of a change of state include:

- a change of state from solid to liquid

melting

- a change of state from liquid to solid

Freezing

- a change of state directly from solid to gas, skipping the liquid state

Sublimation

- a change of state directly from gas to solid, skipping the liquid state

Deposition

- a change of state from gas to liquid

Condensation

- a change of state from liquid to gas; occurs at the surface of a liquid

Evaporation

- a change of state from liquid to gas; occurs throughout the liquid

Boiling

Multiple Choice

Matter can change back and forth between any two states of matter.

• true

• false

Energy

- the ability to cause changes in matter

- is always involved in changes of state - particles of matter either absorb or lose energy when matter changes from one state to another

Multiple Choice

Why is energy involved in changes of state?

• Energy is always absorbed when there is a change of state.

• Particles of matter do not gain or lose energy when changing state.

• The energy of particles of matter determines the matter's state.

• Energy is always released when there is a change of state.

Multiple Choice

All physical changes of matter are reversible.

• true

• false

Multiple Choice

Sawing up a tree to get firewood is an example of a reversible physical change.

• true

• false

Multiple Choice

Melting ice is an example of a reversible physical change.

• true

• false

• cutting

• chopping

- examples of irreversible physical changes include:

• bending

• stretching

• changes of state

- examples of reversible physical changes include:

A physical change can sometimes be reversed, but sometimes cannot be reversed.

Multiple Choice

Which of the following is an example of an irreversible physical change?

• melting a piece of lead

• sharpening a pencil

• dissolving sugar into water

• boiling water