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Home » Key Stage 2 Science » Tea bag diffusion!

Tea bag diffusion!

Modified: Feb 23, 2023 · Published: Jan 2, 2012 by Emma Vanstone · This post may contain affiliate links · 9 Comments

I love a good cup of tea. In fact, I cannot actually function without one first thing in the morning. If you’re like me, then this investigation is definitely needed in your house so that you can ensure your kids are equipped with the best tea-making skills and have the best scientific knowledge to back up what makes a good cup of tea! This investigation looks at diffusion through the partially permeable membrane of a tea bag.

So firstly, we want to know what type of teabag makes the best drink?

Is it a square, a pyramid or a circle bag?

The activity involves using hot water, so adult supervision is essential.

Teabag diffusion

You’ll need

A stopwatch/timer

A piece of white paper

A pen

3 clear glass mugs (you are going to add hot water, so not thin ones that could crack)

Circle, triangle and pyramid tea bags

Thermometer or kettle

tea bags, a phone, glass mug and paper

Method

1. On the piece of white paper, draw a cross with a marker pen

2. Place one mug over the cross

3. Add the circle teabag

4. Boil water from the kettle and measure out 150ml (if you have a thermometer, you can improve reliability by keeping the temperature constant)

5. Pour over the teabag and start the stopwatch

6. Time how long it takes for the cross to disappear

a cup of tea in a clear glass mug and a phone for a diffusion science activity

7. Repeat with the pyramid and square teabag.

8. To make the investigation results more accurate, repeat with each teabag three times.

Record your results in a table

Investigating teabags Multiple Mummy

How does the tea diffuse into the water?

So which teabag was quicker?

You should find that the pyramid teabag was the quickest.

Why do you think this is?

As the water is added to the teabag, it causes the tea leaves to move and triggers diffusion of the leaves. Diffusion is defined as the movement of a substance from an area of higher concentration to an area of lower concentration. There are lots of tea molecules in the bag and none outside. The leaves themselves can’t pass through the bag, but their smaller particles containing colour and flavour can (the teabag itself acts as the partially permeable membrane). The addition of heat (from the hot water) to the tea bag causes its molecules to move much faster than at room temperature. This energy is more readily released in a shorter period of time than a tea bag filled with room temperature or cold water. The teabag shape affects the surface area and the pyramid due to its 3D shape providing more surface area for diffusion to take place and more area in the middle for the tea molecules to move around in spreading the colour and flavour.

Ok, so now they know which is the best teabag to use and how to let it brew…so I suggest you ask for a nice cuppa now!

Last Updated on February 23, 2023 by Emma Vanstone

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Safety Notice

Science Sparks ( Wild Sparks Enterprises Ltd ) are not liable for the actions of activity of any person who uses the information in this resource or in any of the suggested further resources. Science Sparks assume no liability with regard to injuries or damage to property that may occur as a result of using the information and carrying out the practical activities contained in this resource or in any of the suggested further resources.

These activities are designed to be carried out by children working with a parent, guardian or other appropriate adult. The adult involved is fully responsible for ensuring that the activities are carried out safely.

Reader Interactions

Comments

  1. Brooke @let kids create

    January 06, 2012 at 8:20 pm

    What a fun experiment. You always find ways to make the most ordinary things interesting. Thanks for sharing on Monday Madness.

    Reply
    • ScienceSparks

      January 06, 2012 at 9:43 pm

      Thanks. x

      Reply
  2. Art For Little Hands (@art4littlehands)

    January 08, 2012 at 5:37 pm

    Interesting especially since all my tea bags are rectangular. I don’t drink it a lot, but and getting to like it more and more. I haven’t tried many brands yet so I will have to start exploring it more. Fun exploration with the kids and I think they probably learned a lot about figuring things out on their own from it.

    Reply
  3. maddy

    October 23, 2013 at 2:29 am

    awesome job

    Reply
  4. Shudu

    February 17, 2014 at 8:32 pm

    Jah hey thnx.i have learned smthng http://

    Reply
  5. Jane

    February 23, 2014 at 12:40 am

    Where did the square teabags come from? I have enjoyed tea in that shape but can’t recall what brand. Thanks!

    Reply
  6. Ailbhe and Danielle

    April 29, 2014 at 7:13 pm

    thanks! thats really helpful we’re doing a science project on how the shape of the tea bag affects the taste so that was really helpful!!

    Reply
  7. Tazzy

    September 17, 2017 at 11:32 pm

    Interesting and helpful. Thanks a lot. Although the cross takes a long time to remove for some reason. Wasnt sure in what marker to use though.

    Reply
  8. dixie wrecked

    September 29, 2019 at 5:28 pm

    WOW i love talking about tea irs so fun wowowowow i learnt science from tea omg wowowowowow omg tea is so interesting

    Reply

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