Lemon juice and tea colour change : Fizzics Education

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Lemon juice and tea colour change

Lemon juice and tea colour change

Follow FizzicsEd 150 Science Experiments:

You will need:

  • A kettle
  • Either a ceramic mug or a heatproof glass (we used a glass to show the colour change clearly)
  • Lemon
  • Teabag
  • Knife
  • Chopping board
  • Adult help!

The lemon juice and tea colour change is subtle but it works!

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A metal kettle, knife, glass, tea bags on a wooden chopping board in sunlight
1 A lemon chopped in half

Ask an adult to cut a lemon in half.

2 Hot water from a kettle being added to a glass with tea bags

Ask an adult to boil a kettle and then add the hot water to tea bags in a mug or heatproof glass. You may want to choose a white mug to see the contrast in the colour change.

3 A glass of hot tea in sunlight

Allow the teabag to sit in the hot water for a minute or so and then take it out. As an option you could setup a camera to take a photo of the water’s colour for reference of the colour change later.

4 Squeezing a lemon half into a glass of tea

Squeeze a few drops of lemon juice into the glass and watch the colour carefully (again, if you use a white mug you will have a good background to see the colour change more easily)

5 Light brown tea in a glass

You should have seen the tea go a lighter shade of brown! If you had a setup a camera prior, take another photo and then use a service like Adobe Photoshop or an app such as pixel picker to compare the hex codes to get a fair result without bias.

6

Try squeezing even more lemon into the tea! In this photo we squeezed several lemons into tea and we found the tea go a much lighter colour.

What is going on?

Black tea contains pigment called thearubigins. These are typically a red/brown colour in water, however if the water is acidic the pigment changes to a much lighter colour. Lemon juice is acidic and by adding some drops of lemon you quickly change the pigments in the tea! These pigments also become much darker in alkaline conditions.

You can also make your own indicator using cabbage juice too! We used this recently as an example of modelling how a pandemic spreads in a classroom.

Variable to test

  • What happens if you use more than 1 teabag?
  • Do limes, grapefruit and other citrus fruits produce the same effect?
  • What if you use apple juice or other juices?
  • Try soft vs hard water
  • Try different teabags from different companies.
  • Try green tea vs black tea

More on variable testing here

Learn more!

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