Learn more about gases by creating a soft drink fountain using lollies. What a sweet way to find out more about chemistry!
You will need
- 2 L bottle of soft drink
- piece of paper or a tube for the lollies
- pack of lollies (such as Mentos or Kool Mints)
- outdoor area.
What to do
Do this activity in an outdoor area.
- Open the bottle of soft drink and place the bottle on the ground so it will not tip over.
- Roll up the paper into a cylinder that's just wide enough for the lollies to slide through.
- Put your finger over the bottom of the roll and ask your friend to put the lollies into the paper tube.
- Hold the tube of lollies just above the bottle and remove your finger so all the lollies drop straight in. You need to drop all the lollies into the bottle at the same time.
- As soon as you have done that, move away from the bottle as quickly as possible.
- Diet soft drink works just as well and is less sticky to clean up as it contains no sugar.
- Orange soft drink doesn’t always work. Neither does Solo as it is light on fizz.
- Experiment with different types of lollies - Kool Mints were used in this activity. Try Mentos or other sugar coated lollies.
- Experiment with the soft drink at room temperature or from the fridge.
Soft drink is bubbly because carbon dioxide gas has been forced into the bottle under pressure.
Until you open the bottle, the gas mostly stays dissolved in the liquid and cannot expand to form bubbles, which the gas will do when not under pressure.
If you shake the bottle and then open it, the gas escapes with a whoosh, taking some of the soft drink along with it. Adding anything to a soft drink enables more bubbles to form and escape.
Try stirring soft drink with a spoon - it gets less fizzy.
The lollies provide lots of surface area very quickly, which means the bubbles of gas form very rapidly in huge numbers.
You need non-smooth surfaces to enable the gas to form.
Both sand and sugar have the same effect when dropped in soft drink.
When you look at a glass of soft drink, there are normally just a few streams of bubbles coming off specific points on the glass where the surface is uneven.
Sometimes you see a stream of bubbles coming from the middle and if you look carefully you can often see a piece of dust with bubbles coming off its end.
The place where the bubbles start to form is called the centre of nucleation.
As the lolly dissolves, it forms hundreds of nucleation points which are tiny pits on the surface of the lolly where more carbon dioxide bubbles can form.
When all this gas is released, it thrusts the entire contents of the bottle skyward, in an incredible soft drink blast.
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