# ThermalExpansion

OP23 investigate and describe the expansion of solids, liquids and gases when heated, and contraction when cooled

Try this 1st!

you can use a water ballon,

1. Fill a water balloon with enough water as so the balloon is bigger than the opening of the bottle
2. Pour some boiling water in the bottle (make sure the bottle is not cold).
3. Place the water balloon over the mouth of the bottle.
4. Wait and observe.

What happened?

Why did this happen?

taken from "Physics on stage 3"

Title

Expansion of solids when heated

Apparatus

A set of Brass Ball and Ring apparatus,

Bunsen Burner

Method

1. Ensure the ball just passes through the ring
2. Holding the ball apparatus by its insulating wooden handle place it in to the hot part of the bunsen flame
3. Hold here for about a minute, turning it in the flame
4. Hold up the Ring apparatus and check if the ball goes through the ring
5. Allow to cool, and try again

Safety Concerns

Always wear Goggles when using a Bunsen Burner

Tie up long hair

Push Stools under desks, leave all passageways clear

Results / Observations

What happened

Conclusions

Most solids expand when they are heated.

Because of this the Eiffel Tower is usually about 15 cm taller during the summer than during the winter.

All solids expand, look at the following 2 pictures and write down what you think they have to do with thermal expansion.

Not all solids expand at the same rates

bi-metallic strip

Metals expand and contract at different rates according to changes in temperature, so a bi-metallic strip will curl when the temperature changes.

A Bi-metallic strip is used to turn on and off thermostats.

Metals are solids and when they heat they _______. However they do not all expand at the same rate.

The 2 metals are bolted to each other and so the end cannot get away from each other,

This causes the strip to bend, this can then be used in circuits to turn on or off thermostats.

bi-metallic strip

Expansion of Liquids

Apparatus

1. round bottomed flask, glass tubing, rubber bung

Bunsen Burner

Method

1. Take a round bottomed flask, add some coloured liquid to it.
2. Place a single holed bung with a glass tube through it.
3. This glass tube must go under the level of the water. (try putting the bung in at an angle until ready to secure it, this should keep the water in the tube low.)
4. Heating the apparatus by bunsen & tripod, or even just in your hands, watch what happens the water level in the tube.
5. Remove the heat and allow the apparatus to cool down.
6. Observe what happens the water level as the apparatus cools.

Safety Concerns

Always wear Goggles when using a Bunsen Burner

Tie up long hair

Push Stools under desks, leave all passageways clear

Results / Observations

What happened

Conclusions

Expansion of Gases

When Gases heat they too increase their volume, this is the reason that footballs are more 'bouncy' when they are left in the sun.

Apparatus

1. round bottomed flask, glass tubing, rubber bung, beaker of water, retort stand

Method

1. Gather the apparatus required
2. Set up the apparatus as shown in the diagram, use a retort stand to hold the round bottomed flask, by its neck.
3. With Goggles on, heat the round bottomed flask with the hot flame of the bunsen burner.
4. Observe what happens
5. Heat for about a minute.
6. Allow to cool, observe what happens.

Safety Concerns

Always wear Goggles when using a Bunsen Burner

Tie up long hair

Push Stools under desks, leave all passageways clear

Results / Observations

What happened

Conclusions