Thermal Expansion of Water: Demonstration and Explanation

Many substances expand when heated (e.g air or metal). Water also expands when heated (note that the thermal expansion of water only begins above four degrees Celsius).

To demonstrate the thermal expansion of water a 750mL plastic bottle is filled with water and a drop of blue food coloring. A straw is put through the bottle cap and sealed so there are no leaks. The level of water in the straw is measured and then a lamp with a 100 watt bulb is turned on and directed at the bottle.

Measurements of the water level are taken for two hours to show the thermal expansion of water. When the light is turned off, the water cools and contracts, returning to its original position.

The thermal expansion of water is one of the primary causes (along with ice melt) of the rising sea levels on earth. As the global average temperature increases the water in the oceans expands occupying more volume. This leads to sea level rise.

[ipecc]

This is a great demonstration of thermal expansion in water! Simple, yet effective.

[treacle]

The best example yet, a good explanation and exactly what I was hoping to see. 👍

[kidbrown]

Thank you. You helped me understand Climate Change a little better.

[jacquiemorgan]

Hi I'm using your idea for the science fair and I was wondering what did you use for the reflective case for the light bulb. Thank you- Jaycee

[jessemoral]

Hey! I like your experiment/video. I did some reading on how to figure out the rate of expansion but can't relate it to real world.

For instance, if I have a pool... Let's use a hot tub/ instead. Okay, the waters 50° (let's say in fall, spring or winter) and I heat it to 100. Is the expansion noticable?? If so, what percentage of increase would you get in this example?

[PraisePius-qf]

Thank you
I understand better
God bless you sir🤲

[wbreslyn]

You could ask something about how much water will expand when heated (in this case by light).  For a science project you could relate this experiment to sea level rise.  The light represents the sun, the water the ocean.  --- Dr. B

[moshariff]

Wow. I remember using this for my science fair almost five years ago. Time

[Nichemusic]

What would be a good Scientific question to put on a experiment for this?

[mikemckeaney]

This experiment really can't relate to sea level rise because there is no temperature measurement. Did the temp in the bottle increase by 1 to 2C as warming model suggest? We don't know.

[kunz]

what was the temperature range of the water during your experiment?

[thomaswolfe]

This is great. Going to use in my biology class. Thanks.

[Twizzlu]

how do you get the straw though the cap with out having air in it

[matthewheersink]

How hot did the water get before thermal expansion took place?

[ashtwenty]

Hello. What was the temperature of the water at the end, and what is the volume increase? I'm also curious of the pushing force of the expanded water ie pressure and weight

[TheMichellekcaldwell]

How would I ensure there is no air in either the straw or water bottle..

[clinton-crimefamily]

Could this explain the tides? As the sun goes over water it expands the water....then as it turns night it contracts....leading to tides.

[MrRem]

What is a good hypothesis for this project?

[rajeshbali]

What if the bottle is closed . Is it burst

[varunavaira]

+Wayne breslyn(Dr.B) can I do this experiment with matchbox