Changes of state
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Electricity
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States of matter
Living things and their habitats
Animals, including humans
Explainer Video
Summary
Changes of state
In a nutshell
Substances can change from one state of matter to another. The processes that happen when a state change occurs are: condensation, freezing, melting and evaporation.
Change of state
Definition
A change of state occurs when one state is changed to another when being heated or cooled.
Example
A liquid is changed to a solid.
Processes occurring when a state is changed
There are different changes of state that you need to know about. These are described in the table below.
process | what is happening | change in state | example |
| Condensation | Cooling of gases | Gas to liquid | Warm air condenses to water at a cold window. |
| Freezing | Cooling of liquids | Liquid to solid | Water turns to solid ice in the freezer. |
| Melting | Heating of solids | Solid to liquid | An ice lolly will melt if left in the sun, turning to a liquid. |
| Evaporation | Heating of liquids | Liquid to gas | A glass of water left in the sun will be heated and turned to water vapour. |
Note: Different materials will change states at different temperatures. The temperature that water will freeze at is . The temperature that water will evaporate at is . This is called the boiling point of water.
Example
A material has changed state from a solid to a liquid. What type of process is happening?
The solid is being heated to form a liquid. A melting process is occurring. For example, a solid ice cube can melt and turn into liquid water.
FAQs - Frequently Asked Questions
How does one state change to another state?
A state will change to another state by either heating or cooling the material.
What is a state change?
A state change occurs when a state of matter is being cooled or heated to form a different state.
What are the four ways a state change can occur?
State changes can occur by: condensation, freezing, melting and evaporation.