We are loving seeing the rainbows in everyones windows so this weeks kit is full of experiments all about COLOUR! In your kit you should have:

• 4 chromatography strips
• 4 litmus test strips
• 1 felt tip pen
• 1 pair of diffraction glasses
• 2 cocktail sticks
• 1 rainbow spinner template
• 1 blank template

Chromatography

• Take one of your chromatography strips from the bag.
• Take your felt tip pen and draw a black circle in the middle of it (make sure to colour it in).
• Get a cup of water, you only need a little water in the bottom of the cup, you don’t want the water level to reach the felt tip pen on your strip. An egg cup would also work!
• Place your chromatography strip in the water – standing upright so that just one end of strip is in the water.
• Watch the water travel up the strip and the colours start to appear from your felt tip! Which colours can you see?
• If you have some felt tip pens at home, you could try some different colours on your spare strips.

Note: If you have a pipette from our chemical reactions kit, you could try gently dripping some water onto the strip instead. Chemical Cress is here to explain why this colourful reaction happens – [embedyt] https://www.youtube.com/watch?v=LMN572EL66k[/embedyt]

Litmus Test Strips

For this next experiment you could use your pipette if you have one, but if you don’t – don’t worry! Your finger will work just as well. Litmus strips tell us if something is an acid or an alkali, or neutral (not an acid or an alkali). Chemical Cress will start by telling us a little bit about acids, alkalis and the pH scale – Your litmus strip may look a little different to Chemical Cress’ – that’s ok! It will still work the same. The only thing that is different is the key isn’t attached the strip. This is your key – [embedyt] https://www.youtube.com/watch?v=qt0PjuHCjAc[/embedyt]

• Choose 4 liquids – these could be found in your kitchen e.g orange juice, vinegar, washing up liquid, milk. You don’t have to choose these liquids, you can choose any that you like (as long as a grown-up says it’s okay!).
• Lay out your litmus strips – one for each liquid.
• Either using your finger or your pipette, put a drop of the liquid in the square in the middle of the strip.
• Which colour did it turn? Match it to one of the colours on the strip, this will tell you if it is an acid or an alkali! 1-5 = Acid 6-7 = Neutral 8-14 = Alkali
• Try each of your liquids – did any surprise you?

Extra expriment: Did you know? Cabbage water also works as a pH indicator! Just chop up some red cabbage, put it in some boiling water until the water changes to blue/purple, then add your chosen liquid and watch it change colour! If you add an acid it will turn red/pink and if you add an alkali it will turn blue/green!

Rainbow Spinners & Diffraction Glasses

• Cut out your colourful rainbow spinner. You may need to ask a grown-up to help you!
• Carefully poke your cocktail stick through the middle of the spinner.
• Hold it in front of you and spin it quickly, what do you notice?
• You should see that the spinner starts to look white!
• Now take your diffraction glasses and put them on. What can you see?
• If you look somewhere bright, like out of the window, you should be able to see lots of rainbows!

Extra acivity – why not try colouring in your blank rainbow spinner (colouring pens or colouring pencils will work)?. Make sure you only use the colours of the rainbow! Chemical Cress is going to tell us all about rainbows now – [embedyt] https://www.youtube.com/watch?v=IDcuasIucOY[/embedyt] If you would like to make some more rainbow spinners, they can be downloaded and printed here – Rainbow spinner (empty) Enjoyed this kit? Visit our shop for more weekly science kits