The pupils in Cedars 1 were very excited to be part of Ravenswell Science Fair and could not wait to get involved.
Our task was to:
- Investigate how materials may be changed by mixing
- Make a Lava Lamp
As part of our experiment we needed to look at chemical energy to try and understand what was going to happen to the materials when we mixed them together.
We had to do a bit of research but we found out that chemical energy is energy that is released during chemical reactions. Batteries, food, and fuels such as coal, oil and petrol are all stores of chemical energy, which can be released under certain conditions e.g. connecting batteries into a circuit, chewing food, burning fuels etc.
We looked at the equipment we needed to design a lava lamp and did some mini experiments with the materials to observe what would happen to them when we mixed them together.
- Vegetable oil
- Measuring jug
- Clear plastic container or bottle
- Food colouring
- A fizzy tablet (Alks-Seltzer)
We made some guesses or predictions about what we thought might happen when we added the following materials together:
- Oil and water
- Food colouring and water
- Food coloring and oil
- Fizzy tablet and water
- Fizzy tablet and oil
- Each pupil predicted their answers and then checked them against the results of the tests.
- We made our predictions and recorded them on the board for everyone to see!
The results were interesting! We observed that:
- Oil and water DO NOT MIX!
- Adding food colouring colours the water.
- Food coloring stays in ‘blobs’ in the oil because food colouring does not dissolve in oil.
- The fizzy tablet dissolves in the water and makes a fizzing sound.
- The fizzy tablet did not dissolve in the oil.
Now it was time to put the lava lamp together.
The steps involved in this were as follows:
1.Use a measuring jug to measure 250ml of water and fill the bottle/container with water.
2.Use the funnel to pour in the vegetable oil into the bottle until it is almost full. Wait for the oil and water to separate.
3.Add some drops of food colouring (about 10) to the bottle. We chose red.
4.Break a fizzy tablet in half and drop it into the bottle.
Watch to see the bubbling begin!
So how does it work?
As we already saw, oil and water do not mix. Oil is lighter than water so it sits on top of water when it is added. The food colouring does not dissolve in oil; it is heavier than oil. It falls through the oil down to the water and mixes with the water.
Alka-Seltzer tablets contain two chemicals (citric acid and bread soda) which form a chemical reaction when they meet water. This produces a gas called carbon dioxide gas.
When you drop the Alka-Seltzer tablet into the oil and water, it falls down through the oil to the bottom, where it reacts with the water to produce carbon dioxide gas. These bubbles of gas rise through the oil to the top of the bottle because they are light. They take some coloured water with them. The bubbles of gas burst when they reach the top, the gas escapes, and the drops of coloured water sink back down through the oil.
We really enjoyed this experiment and we hope you enjoyed our blog post. We look forward to seeing you at the science fair!