The thirsty bottle experiment
Everyone loves a good magic trick and while I never present our experiments as being magic, I do sometimes like to "wow" the kids with an experiment before we walk through the science 😊. This is definitely one of those experiments. I set it all up and heated the bottle before I called the kids to watch. I was rewarded with Lily's eyes nearly falling out of her head!
So if you want to impress your kids with items you are likely to already to have around the house, read on!
- 1 clear glass bottle.
- 1 Plate
- Food colouring
- Boiled water that is still very hot
- Room temperature water
- Pour the room temperature water onto the plate and add a few drops of food colouring of your choice.
- Boil some water in a kettle. If you do not have a kettle, you can heat water on a stovetop or microwave.
- Pour the hot water into the glass bottle. Be careful not to burn yourself.
- Empty the hot water out of the bottle into the sink (use a tea towel or oven mitt to hold the bottle so that you don't burn yourself).
- Now the fun part! Place the bottle onto the plate (opening down) and watch it suck up all the water!
When the hot water is tipped out of the bottle it leaves the bottle’s walls warm. This heats the air inside the bottle which causes it to expand. When the bottle is tipped over onto the plate this air becomes trapped. As the air cools it takes up less space. This causes the water to travel into the bottle to take up the vacant space. This happens because the vacuum created by the shrinking air particles has more force than the gravity that was keeping the water in the plate.
You can use this experiment to look at forces and the nature of gasses (in this case the space occupied by hot air versus cold air).
If you have a science loving child then check out our Chemistry-in-Action kit with everything they need for hours and days of experimenting fun.
If you enjoyed doing this experiment, you may also like these other free experiments.