Lava Lamp Experiment
We’re back with another summer camp science session today. If you missed the introduction I recommend you go back and read it as it includes some general tips for all our science sessions.
This week we are going to do a fun experiment which only requires a few simple items. Here’s what you will need:
- Vegetable oil
- Food colouring
- Effervescent tables, e.g. Alka Seltzer
- A large, clean jar or bottle – we used an old plastic juice bottle with the top cut off
If you want to record your experiment – including your predictions, observations and findings – you can also download a copy of my free ‘Science Experiment Report’ sheet and either print it off or, if you don’t have a printer, use it as a template to create your own. Depending on age, kids can either write and/ or draw their observations.
I’ve recorded a video of the experiment, which you will find further down the page. However, I recommend you try the experiment out yourselves first before watching the video, and then you can compare your results with ours.
Safety Tip: Careful when handling food colouring so that you don’t stain clothes or surfaces. Do not let children put any Alka Seltzer tablets in their mouth!
Lava Lamp Experiment
Step 1: Fill your jar or bottle roughly two thirds full of vegetable oil.
Step 2: Mix about 100ml of tap water with a few squirts of food colouring,
QUESTION: What do you think will happen if we pour the water in to the oil? Record your predictions.
Step 3: Carefully pour the water in to the oil. The water will sink to the bottom of the jar/ bottle and sit below the oil. It may take a few moments to settle.
QUESTION: What do you think will happen if we drop an effervescent tablet in to the water-oil mixture?
Step 4: Break an effervescent tablet in half and drop it in.
Once the tablet hits the water and starts to fizz, coloured blobs will rise up through the oil and then sink down again. You can add more pieces of tablet to keep the experiment going.
Here’s a short video from when we did this experiment at home:
The water sinks to the bottom of the jar/ bottle, below the vegetable oil, because it is more dense than the oil. When you drop in the effervescent tablet, it also sinks to the bottom and starts to dissolve in the water as it is water soluble. As the tablet dissolves, it releases carbon dioxide. The carbon dioxide gas rises to to the top of the water-oil mixture, taking blobs of coloured water with it. Once the carbon dioxide gas reaches the top and is released in to the air, the blobs of coloured water sink back down. The cycle will repeat until the tablet is fully dissolved and all the carbon dioxide has been released.
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