Fizzy fun with carbon dioxide

I was inspired by Lisa at 5 Orange Potatoes to try this fizzy experiment with the girls today.


  • cooking oil
  • water
  • glass jar or clear plastic bottle
  • food coloring
  • effervescent antacid tablets (aka Alka-Seltzer)

Caution:  Adult supervision needed with young children as this experiment uses OTC medicine


Step 1:  First you fill your jar or bottle about 1/2 full with cooking oil

Step 2:  Add enough water so that you still have about an inch or two of space.

What happens to the oil and water?

They separate into 2 layers because they don’t mix together. [They are immiscible (un-mixable) liquids].  The oil is hydophobic – which comes from the Greek language hydros “water” and phobos “fear” and means “water fearing”.

Why does the water sink to the bottom?

Because it’s more dense than the oil.

Why does the oil float?

Because it’s less dense than the water.

Step 3:  Add 4-6 drops of food coloring in one drop at a time. You might try adding two separate colors to observe color mixing.



What happens to the food coloring in the oil layer?

It forms a perfect spherical shape because the oil and water in the food coloring do not mix and instead creates a perfectly shaped colored water droplet.

What happens to the food coloring in the water layer?

The food coloring itself is water based and so it is hydrophilic or “water loving”.  It forms lovely, lacy patterns as it mxes into the water. The food coloring will spread out and become less concentrated in the larger volume of water.


Step 4: Next, add the effervescent tablet. You can add it whole, or break it into smaller pieces for a more dramatic effect.


Step 5:  Stand by and observe the magic happen:



Why did this happen?

Dropping the effervescent antacid into water created a chemical reaction and carbon dioxide was released. The water/food coloring bubbles were forced back up into the oil layer, creating the wonderful lava lamp effect.


This entry was posted in Chemistry, Density, Fun with color. Bookmark the permalink.

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