How to make dancing grapes?

Dancing grapes, sweet shine grapes
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Dancing grapes experiment

Introduction

In this dancing grapes experiment we observe dancing grapes since they are taken to the surface by carbon dioxide which is dissolved in carbonated water. It is a very easy experiment you can do at home or even in the restaurant with your kids. Just as you, we have another opportunity to introduce physics and chemistry. Moreover, at the end we can eat all grapes! Yummy! 🙂

In our dancing grapes science project we used:

  1. Carbonated water
  2. Grapes (not dancing yet 😉 )
  3. Glass

Dancing grapes science project execution

Because we would like to eat the grapes at the end of our experiment, please wash them before. After washing them make sure to dry them from the water.

Step 1 – Prepare the grapes

Take sweet shine grapes and pick the most beautiful ones

Step 2 – Pour the water

In the step 2 we take carbonated water and fill the glass with it. The best results happen when water is little bit cooler than the grapes. Are you interested why? You will find the answer at the end of this post.

Step 3 – Drop our shiny grapes

Once we are ready, start dropping the grapes into the glass.

Step 4 – Watch the dancing grapes

We can notice that briefly after touching the bottom of the glass, grapes start to move towards the surface. Then moving back and again up.

Explanation for pros

Why the dancing grapes magic happens?

Do you remember what is the density of water? Just as a reminder it is around 1000 kg/m3. Now the hard part: What is density of carbon dioxide? 1.98 kg/m3 (at standard temperature and pressure)

Initially, the average density of grapes is greater than the density of water and therefore the grapes sink. After some time of being in the water, the grape increases in volume due to the gas that surrounded it, and therefore its average density decreases. When it becomes less than the density of water, the grape goes to the surface. Afterwards the carbon dioxide escapes and the situation repeats.

Why the gas bubbles surround the dancing grapes?

As we might know, gas can be released due to the pressure change or temperature change. An increase in temperature can also contribute in the increased generation of carbon dioxide. On insertion of grapes into the carbonated water the temperature around the grapes increases slightly and due to the absorptive property of the grapes’ skin, the generated bubbles stick on to the surface of the grape.

Interesting facts

Carbon dioxide is a component of the Earth atmosphere in minimal amount – about 0.04%, however it is the main component of the atmosphere of Mars and Venus. The atmosphere of Mars contains of 96% carbon dioxide. Near the poles of Mars there are carbon dioxide polar caps which regularly sublime and resublime. Moreover, carbon dioxide is also the main component of Venus atmosphere consisting 96.5%. Therefore, it causes very strong greenhouse effect giving a planet temperature of surface of 480 Celsius degrees.

Summary

Did you notice similar effect of gas bubbles surrounding your skin when entering swimming pool? If you liked this article, you might be interested also in my other post treating about relation between pressure and temperature – Please check my post How thirsty candle is rising water?

Please leave the comment below. We are curious what are your suggestions and results.

1 thought on “How to make dancing grapes?

  1. Wonderful trick, explained in a simple way. I like the fact that i can listen it as podcast, i can watch the video and read it…big thanks!!! 🙂

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