Do five fun egg-speriments this Easter while making meaningful science discoveries. Learn about heat transfer and insulation as you use eggs to keep ice cream from melting in a hot oven. Do a simple pH experiment that produces green eggs. Learn about density as you float an egg between a layer of salty and fresh water. Study air pressure with the classic egg-in-a-bottle project, and grow crystals in the egg "geode" project.
Is it possible to put ice cream in a hot oven without it melting? Oh, yes! Make this delicious dessert to try it out. There are many variations of this dessert—choose the type of cake, ice cream, fillings, and toppings that you like best. You can make one large dessert, or individual ones as we did.
*Safety note: Sometimes the egg whites in the meringue won't be fully cooked. If you're concerned about salmonella, use pasteurized dehydrated egg whites or meringue powder you can buy at the store. You can also use liquid pasteurized egg whites from a carton, although the meringue won't fluff up as much as with fresh eggs.
We know eggs change their form when heated. In this recipe, we see that egg whites also change their form when beaten vigorously! The two changes are caused by the same thing: globular proteins unfolding and forming new bonds with each other. When you beat the eggs, you're adding air bubbles to the mixture of proteins and water in the egg whites. Some of the amino acids in the proteins are attracted to water and some are repelled by it. The proteins begin to unfold so that the water-loving amino acids can move towards the water, and the others can move toward the air pockets. The unfurled proteins bond with each other, creating a network of protein that traps the air bubbles inside, making a nice fluffy, frothy meringue.
Now, the ultimate question—why didn't the ice cream melt completely when you put it into that very hot oven? The answer is that the meringue acted as an insulator, slowing down the transfer of heat. It works kind of like styrofoam (but tastier); the air trapped in small pockets in these materials makes them both good insulators.
Green Eggs and Ham
When you were little, you probably read the Dr. Seuss book Green Eggs & Ham. Do this easy pH trick to make green eggs just like in the book.
What You Need:
What You Do:
Red cabbage contains pigments called anthocyanins, which change colors when they come in contact with acids (low pH) or bases (high pH), making them a natural pH indicator. When the cabbage juice comes in contact with an acid (like vinegar) it will turn red, but when it is mixed with a base it will turn bluish-green. What does this project tell us about egg whites, then? Egg whites are basic (also called alkaline) and so they turn the red cabbage juice green.
Make a regular egg float in a 250 ml beaker! Use a funnel to pour a layer of salt water underneath a layer of water. Do this by placing place the tip of the funnel at the base of the baker filled halfway with fresh water. Make sure its pointy side is up against the side of the beaker. Carefully add an egg and watch it float. Raw eggs float in salt water, but sink in fresh water.
Egg in a Bottle
Learn about the relation of temperature and pressure as you watch an egg get sucked into a bottle. This project requires adult supervision.
What You Do:
First, the science behind a hard-boiled egg: Egg whites are made of water and proteins. Proteins are made of long chains of amino acids, but in an egg the chains are clumped tightly together in individual spheres. (These are called "globular proteins.") When the egg is heated, the proteins and water molecules begin to move faster. As they move and collide with each other, the individual protein chains start to "unravel," eventually bonding loosely with other protein chains, forming a network of protein with water trapped inside. The consistency has changed from runny egg white to a soft solid!
So how does this squishy-but-solid egg get mysteriously pushed inside the bottle? The answer is all about air pressure. When you first set the egg on the bottle, the air pressure inside the bottle matched the air pressure outside, so nothing happened. When you dropped the burning paper into the bottle, it caused the air inside to heat up and expand rapidly. That expanding air pushed the egg aside and escaped from the bottle; that's why you saw the egg vibrating. When the fire consumed all the oxygen inside the bottle, the flame went out and the remaining air in the bottle cooled down. Cool air takes up less space, exerting less pressure inside the bottle. (The egg acted as a seal to prevent outside air from getting in to fill the extra space.) The result was an unbalanced force—the force of the air pushing on the egg from outside the bottle was greater than the force of the air pushing up on it from inside the bottle. Voila - the egg was pushed into the bottle!
How do you get the egg out again? You need to increase the pressure inside the bottle. Turn the bottle upside down and tilt it until the small end of the egg is sitting in the mouth. Now put your mouth close to the bottle and blow, forcing more air into the bottle and raising the pressure inside. When you take your mouth away, the egg should pop out - just be careful it doesn't hit you in the face!
Egg Crystal Geodes
Make sparkly crystal "geodes" inside real eggshells. First you'll need to make a supersaturated solution. For our geodes, we used magnesium sulfate and aluminum potassium sulfate. Can you think of other solids you can use to grow crystals? For this project, plan ahead and reserve the eggshells the next time you use eggs in a recipe.
What You Do:
A crystal is a hard, solid substance made of molecules that bond together in specific patterns to form a shape with straight edges and flat surfaces. If you made more than one type of egg crystal geode, you saw that not all crystals have the same shape or size. The site where a crystal begins to grow, called its nucleation site, determines its size: fewer nucleation sites mean larger crystals, and many nucleation sites produce smaller crystals. A few molecules of magnesium sulfate or aluminum potassium sulfate (or whatever solid you used) found each other in the solution and joined together in a crystal formation. More molecules joined until enough gathered to form a visible crystalline solid. Chemists refer to this as a crystal 'falling out of'? the solution. If you left these crystals in the solution, they'd continue to grow.