Expansion of gases due to heating
Mention the details of the activity in the form of
Aim;
Materials Required;
Procedure;
Observations;
Conclusion.
Answers
Answer:
Materials
Per group of pupils:
A rigid plastic bottle with a lid
Play dough or modelling clay, e.g. Plasticine®
A transparent plastic drinking straw
A pair of scissors
Food colouring (optional)
Tap water
Procedure
The homemade thermometer
Image courtesy of Andrew
Brown
Use a pair of scissors to make a hole in the top of the bottle lid, big enough for the drinking straw to fit through.
Fill the bottle halfway with cold water.
Add a few drops of food colouring and mix.
Screw on the bottle lid and insert the straw through it into the water, making sure that the straw does not touch the base of the bottle.
Seal around the hole in the lid using play dough, thereby fixing the straw in place. The seal must be completely airtight.
Place one hand on the upper part of the bottle. What happens to the liquid in the straw, and why?
What happens?
Old-fashioned mercury bulb
thermometer. The liquid in a
bulb thermometer expands
when heated, causing it to
rise up the narrow glass
tube. The thermometer in
experiment 1 relies on the
expansion of gas, not liquid
Image courtesy of Andres
Rueda; image source: Flickr
The heat from your hand warms the air inside the bottle. The air expands and pushes on the water, causing it to rise up the straw.