Egg-Citing Science (Chemistry/Acids and Bases)
Here's a quick quiz: What do chemistry and cooking have in common? For one thing, they both can get pretty messy! They also require a lot of measurement, but the most important similarity is that they both involve changes in matter. In this investigation we dive deep into the world of kitchen chemistry and explore how matter changes — using nothing but an ordinary egg and some common chemicals found around the house.
Here's what you'll need to play along:
- 3 large (16 oz.) plastic cups
- 3 standard uncooked chicken eggs in their shells
- some water
- a bottle of vinegar
- a bottle of clear ammonia used for cleaning
- 3 large pieces (12" x 12") of plastic wrap
- 3 large rubber bands
- a marking pen or crayon
When most people hear the word chemistry, the first things that usually come to mind are bubbling beakers, mysterious powders, and, of course, explosions! The truth is, the science of chemistry simply looks at how matter changes. Some of the most important changes happen when we use substances called solvents. Solvents are things that cause solid stuff to dissolve, and one of the most important solvents is good old-fashioned water. Other solvents include materials called acids and bases. In this challenge, we take a look at how each of these different types of solvents works on the element calcium. Calcium can be found in many things, including seashells, chalk, your bones, even eggshells! The solvents you're going to test are water, vinegar (an acid), and ammonia (a base).
Begin by placing an egg in the bottom of each cup. Mark the first cup "W" and fill it with water so that the egg is completely covered. Mark the second cup "V" and fill it with enough vinegar to cover the egg. Mark the third cup "A" and fill it with about ½ inch of ammonia. Fill the rest of the cup with water so that the egg is covered. Be careful not to breathe in the ammonia fumes because they can irritate your nose! Place a piece of plastic wrap over the top of each cup and secure it with a rubber band.
Here's the challenge question:
How will water, an acid, and a base affect the structure of an eggshell?
What you do:
First, predict what you think will happen to the three eggs after you let them each sit in a different solvent for five days. Make sure you explain why you think this might happen! Base your ideas on your own experiences.
After you have made your predictions, allow each cup to sit undisturbed for five days, then carefully uncover them. Use the back (eraser end) of a pencil to gently push each eggshell to see if any changes have occurred. When you finish the experiment, carefully pour out the liquid from each cup into a sink and rinse with about gallon of water. Place the eggs in a plastic bag and throw them and the cups in the garbage.
Does this experiment explain why acid rain has an impact on certain buildings and statues? What else might it explain?
Notes to Teachers
Curriculum Focus: Science/Chemistry/Acids and Bases
Learning Outcomes:
- Make predictions based on prior knowledge and experience.
- Observe the effect of various solvents on calcium in eggshells.
- Discuss acid rain and its environmental effects.
Related Web Sites
Try this site for more chemistry-related information and activities:
Chem 4 Kids!
WonderScience is a hands-on elementary school science activity magazine published each month from October to May by the American Chemical Society and the American Institute of Physics. General Science Sites
Science and Technology for Children Curriculum The Natural History Museum (London)
Edison National Historic Site Endangered Species Program