This activity came from Kids Science Experiments.

The idea is to demonstrate the different densities of liquids by dropping different things into a three-layer liquid.

Materials

You will need:

1. One coin (any denomination. I used a penny)

2. One cork

3. Two or three grapes (I didn’t have grapes, so used ground cherries, thinking them about the same density as grapes)

4. Oil (I used peanut oil)

5. Honey

6. Water

4. A tall, clear glass or jar.

Instructions

1. Pour the glass or jar one-third full of honey.

2. Pour the glass or jar one-third full of oil.

3. Pour the glass or jar one-third full of water.

4. Allow the liquids to settle out into layers (2-3 minutes).

5. Drop in the coin.

6. Drop in the cork.

7. Drop in the grapes.

What to Expect

You expect the three liquids to layer nicely, and mine did. The honey was on the bottom, then the water, then the oil on top.

I expected the three objects to float suspended in the three liquids.

What Happened

The coin sank to the bottom of the honey,

The cork floated on top of the oil.

The ground cherries hung, as if in a plastic snow globe, suspended between the water and oil.

I ate the rest of the ground cherries not needed for the experiment.

Follow-Up Experiment.

At this point, I thought, OK, the cherries are floating on the water, like the cork is floating on the oil.

Then, I asked myself why.

If the cherries can just float on water or sink  in oil, then they should be able to do this without any layering.

I went back to the garden to fetch some more ground cherries.

I poured water and oil in new, separate bowls.

I dropped in the cherries.

They both dropped to the bottom of the oil.

One floated and one sank in the water.

Hmmmm.

So, I dropped them all in the original three-layer liquid.

They all floated.

Clearly, the layering of the water and oil is what is suspending the cherries.

The Explanation

Physics professors at Rice University and the University of Houston explain why oil and water seperate, because of their different densities.

You can do a similar experiment to make a grape float by adding salt to the water.

Science project ideas says it is a combination of the density of the liquids and the density of the objects that is causing the effect.

They claim that if I had used a grape, it would have sunk to the bottom of the water, above the honey. A Lego should act like my ground cherries, floating between the water and oil.

You can even use food coloring in the water to enhance the effect.

Suspended grapes. Snow globes in the making.

Have you noticed how easy it is to float in salt water?

Have you ever experimented with floating objects in salt water?

Do you know why oil and water don’t mix?

What would happened if you dropped grapes in the ocean? Cherries? Legos?

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To you and discovering  wonder with your grandchildren.

Carol Covin, “Granny-Guru”

Author, “Who Gets to Name Grandma? The Wisdom of Mothers and Grandmothers”

http://newgrandmas.com

Related articles

• Ground Cherry Jam (kitchenmisfit.wordpress.com)

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View article:
How Do You Suspend a Grape in Liquid? Frugal Friday.