Changes of state

Target: To know about the change of state from liquid

to a solid.

Monday 10 April 2023

Experiment

• Place a test tube containing stearic acid into hot water. The solid will melt.

• Remove the test tube and thermometer and place it in a test tube rack.

• Record the temperature for 15 minutes.

• Plot a graph of your results – show temperature against time.

Time (min) Temperature (oC)

0

1

2

3

4

5

6

7

8

9

A change of state is given a name.

Solid Liquid

Melting

Freezing

Changes of state

• If a liquid is cooled its temperature falls to its freezing point.

• At the freezing point the temperature stops falling while the liquid solidifies.

• Once all the liquid has frozen the temperature of the container starts to fall again.

Changes of state – cooling curves

The freezing point of a substance is the temperature at which the liquid spontaneously turns into a solid.

The freezing point depends of the pressure of the atmosphere above the liquid.

Solid Liquid

Liquid

Liquid Gas

Gas

Solid

Time

Changes of StateT

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ratu

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