Chemical Energy and Capacity

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We had great fun creating lava lamps in 2nd class.

Now we know that chemical energy is energy released during a chemical reaction.

We found out that oil and water do not mix. Water is heavier than oil.

For our lava lamps we used effervescent tables (these are tablets that dissolve in water) called Alka Seltzer. These tablets have two chemicals in them called citric acid and bread soda.

If you follow our experiment you can make your own cool lava lamp.

Here is our experiment

Title: To design and make a lava lamp and learn about chemical energy.

Equipment: Effervescent tablets, food colouring, oil, water, plastic bottle

Prediction: I predicted that the oil and water would not mix and that the food colouring and oil would mix.


  1. Find out the capacity of the bottle by filling the bottle with water and empty water into measuring jug.
  2. Calculate a quarter of the capacity of the bottle and put this amount of water in the bottle.
  3. Now calculate two quarters of the capacity of bottle and add this amount of oil to the water
  4. Now add about 8 or 10 drops of food colouring to the bottle.
  5. Break the effervescent tablet (alka seltzer) into pieces and drop them into the bottle.
  6. Leave the bottle for an hour or so, observing it from time to time.
  7. Now add another bit of alka seltzer tablet and observe what happens.

We will update you with our results and conclusion next week!


We used our maths skills today to find out how much water and oil was needed in each bottle.

If you have a litre bottle = 1000ml you will need to fill it with a quarter of a litre of water which is 250ml and two quarters of a litre of oil which is 500ml.

If you have a 500ml bottle you will need to fill it with a quarter of 500ml of water which is 125ml and two quarters of 500ml of oil which is 250ml.

Check out our capacity post here.