Jessica Blindt

The Magic Eggs

Science Concept: Density

Every liquid has its own density. An object will therefore behave differently in each liquid.

Materials:

3 eggs

3 - 400 mL beakers

225 mL water

225 mL of 3 M hydrochloric acid (You may substitute vinegar for the hydrochloric acid)

60 g of sodium chloride dissolved in 225 mL water (salt water)

Long pair of tongs or a spoon

Pre-demo Prep:

Fill the beakers with each of the 3 fluids. Draw faces on the eggs to personalize them. Have the eggs ready to be placed into the liquids.

Directions:

Tell the first egg to float. Using the tongs or spoon, put the egg in the salt water. It will float. (If it doesn't, add a little more salt) Next, tell the second egg to swim. Put this egg in the hydrochloric acid. It will swim to the top while creating bubbles and rolling around. Last, tell the 3rd egg to dive. When put in the water, it will sink to the bottom.

Introduction:

I have the only 3 magical eggs in the universe. Why are they magical? Because they have ears! They can hear what I tell them to do and then they do it! Anything I want them to do, they will. Watch these special eggs...

Explanation:

When an object is placed in a liquid, it will either sink, float or react with the liquid. Density is the cause of all 3 options. Density is the mass of an object divided by its volume. The wieght of the object, in this case the egg, is constant. If an object is heavier than the liquid it is in, it will sink to the bottom and we say this object is denser than the liquid. This was shown by the egg in the water.

In the second case salt is added to the water. The extra salt dissolved in the water causes it to become more dense. If density of the liquid is greater than the object, it will float to the top, and we say this object is less dense than the liquid. This was shown by the egg in the salt water.

The egg in the hydrochloric acid is lighter, because the gas bubbles provide a floatation device, than the acid so it stayed at the top. The bubbles occurred because the calcium carbonate on the egg shell reacted with the acid. Carbon dioxide bubbles are produced, causing the egg to rotate and spin. The carbon dioxide bubbles on top of the eggs break. In the meantime more bubbles are attached to the bottom of the egg. These bubbles now cause the egg to spin and repeat the process.

The bubbles attached to the egg also made it less dense.

Safety Precautions: Be careful when handling the hydrochloric acid. It can burn your skin if you spill some on your hand.

Waste Disposal: Dump all liquids into the sink when finished. Discard eggs, especially the hydrochloric acid one.

Reference: Unknown.