#ScienceLessonAtHome of the day!
Rainbow Cocktail
A demonstration of density dissolving and diffusion.
You will need:
✅6 glasses
✅Sugar
✅4 different food colourings
✅ Food flavourings - Optional (eg. Vanilla extract, peppermint, lemon essence, coffee essence, rum flavour).
✅Warm water
✅A syringe or turkey baster (if you don't have one, a dessert spoon )
✅Stirrer
1. Line up four of your glasses. Add 60ml of warm water (1/4 cup) to each. You need it as warm as possible without the risk of burns.
2. Add 1 tablespoons of sugar to the first glass, 2 tbsps of sugar to the second glass, 3 tbsps in the third and 4 tbsps in the fourth glass.
3. Stir really, really well. All the sugar must have completely dissolved in each glass or this wont work. If there is some sugar that wont dissolve, try warming it up a little in the microwave.
4. Now add a few drops of a different food colouring to each of the four glasses.
5. Add a few drops of a different flavouring to each of the four glasses (optional). And give each glass a last stirr to make sure they are well mixed.
6. Now take your two empty glasses. Using the syringe or baster, put a layer of the mixture with the most sugar in it at the bottom of the two empty glasses. Now, very carefully, use the syringe to add a layer of the mixture with three tablespoons of sugar on top of this.
Next the water with two tablespoons of sugar and finally the one with the least sugar in it.
7. If you don't have a syringe, use a dessert spoon. Hold the spoon at an angle, so that the tip is just touching the surface of the liquid in the glass, the back of the spoon uppermost. Dribble the water onto the back of the spoon. Like you would when floating cream on coffee.
8. If you have been steady handed, you should end up with two lovely layered rainbow cocktails.
Make it clear to your child that we never normally eat or drink science experiments. This time it's okay because we have only used edible things. They can now try a little of one.
FOR THE LOVE OF MURPHY DO NOT LET THEM DRINK ALL OF IT!
It contains a lot of sugar and will send them nutty. They can use a straw to try a sip of each layer, then maybe a sip to try it altogether. This step is much more fun if you added flavours.
9. Place the second glass out of the way somewhere. It will look pretty on the window ledge. Keep checking it a few times a day.
10. Eventually, the colour layers will mix. The warmer the place you put it in, the faster this will happen. This is because of diffusion.
(If you have any of your liquids left, make a third cocktail. Put one of the cocktails somewhere warm and one somewhere cool. See which one gets mixed up fastest.)
The Science at Work
Dissolving - When sugar dissolves in water, the sugar particles separate and "hide" between the water particles.
Density - The more sugar we add, the heavier our 60ml of water becomes. A tablespoon of sugar weighs about 12g. So the first batch of water weighs 72g the second 84g etc. They all have the same volume. The heavier ones are DENSER.
Less dense liquids will float on denser liquids.
Diffusion - Particles in liquids and gasses are always moving around randomly. The warmer the liquid / gas is, the faster they move. This causes your cocktail layers to eventually mix up, and is why this will happen faster in a warm place.
Secondary Students
Draw pictures to show the particles in a solid, liquid, gas and solution. Resources here ⬇️
bbc.co.uk/bitesize/guide…
bbc.co.uk/bitesize/guide…
Find out about "Brownian Motion".
Safety:
Be careful to avoid burns by keeping the water no more than hand hot whilst the child I'd handling it.
Food colouring may stain.
DO NOT LET THEM DRINK THE WHOLE THING. It contains a LOT of sugar.
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