Liquid density rainbow

THE SCIENCE LAB

Make & Do Activity Kit

Liquid density rainbow Explore the different properties of liquids. We look at viscosity, density and miscibility of everyday liquids in this colourful, simple and fun experiment.

Time: Approximately 45 minutes + Difficulty: Hints: Step 4 involves two miscible liquids and will

require patience so the layers don’t mix. Don’t worry if they do! It really is very hard to keep them apart.

the golden syrup into 1. Pour the bottom of the jar filling 1/6th of the jar. Use the same amount for each of the following liquids. the glass slightly 2. Tip and slowly pour in the dishwashing liquid. Tipping the jar slightly will help to stop liquids mixing together.

What you will need: • water 
 • vegetable oil • rubbing alcohol (or gin, Tequila or vodka) • a tall clear glass jar and lid

• green food colouring • blue food colouring • golden syrup (or honey, treacle, maple syrup, dark corn syrup) • dishwashing liquid

Note - The exact amount of each liquid will depend on the size of your jar. Each ingredient will fill 1/6th of the jar.

2 drops of blue food 3. Add colouring to water. Add very slowly to the jar, trying not to mix the liquids.

2 drops of green food 4. Add colouring to the alcohol. Pour into the jar by dribbling down the side of the jar very slowly. This is the most difficult step.

Note - This experiment involves the use of alcohol and will require adult supervision in collecting the ingredients.

the vegetable oil to 5. Add your jar. Stand your jar on a table and allow to settle.

all the layers. 6. Notice Observe that some layers have mixed more than others and some very clearly will not mix. Why do you think that is? 500 Harris st. Ultimo

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THE SCIENCE LAB

Make & Do Activity Kit

Liquid density rainbow

Page 2

What’s going on?

What else can i do?

Different properies

Experiment 1 - Miscibility

Why do the liquids in your jar stay separated in their layers? Why do some liquids stay mixed and others return to their different layers after being shaken?

Pour equal parts oil and water into a jar. Close the lid tightly and shake. To make the results more clear, mix a little food colouring with the water before pouring into the jar.

Each liquid has different properties. Each liquid has a different density and viscosity. Some are immiscible liquids and some are miscible.

Are these liquids miscible or immiscible? How long does it take to separate again? Does this change if the liquids are shaken for a longer time? Which liquid is more dense?

Density A liquids position in the glass jar indicates its density compared to the others. The more dense the liquid, the closer to the bottom it will be. You float in the sea more easily than in fresh water. This is because of the difference in density between the salt water in the sea and the water in your body. You’re body is closer to the density of fresh water and so it is harder to float. Viscosity Viscosity is the measure of a liquid’s resistance to changing its shape. It is the ‘thickness’ of a liquid. Tomato sauce has a high viscosity and so will pour more slowly out of a bottle than water, which has a lower viscosity.

Experiment 2 - A refraction experiment Do the experiment on the first page again. This time do not shake the jar. Take a stick and insert it into the jar so that the stick touches the bottom. Observe the stick from the side. What do you see? Each liquid bends the light coming through the glass in a different way. All liquids have a property called the refractive index. This is the measure of how much light will be bent when it passes through a material. The refractive index will increases with density.

Miscibility Miscibility is the measure of how well two substances mix. Water and alcohol are miscible. They mix together and stay mixed. Water and oil are immiscible and so do not mix. It doesn’t take long after you stop mixing these two liquids for the oil to float back to the top. You may notice this with salad dressing.

500 Harris St Ultimo PO Box K346 Haymarket NSW 1238 Australia

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This work is licensed under the Creative Commons Attribution-NonCommercialShareAlike 2.5 License.