The Unusual Structural Strength of Eggs!
There are many easy and fun experiments that can be done with eggs, encompassing a number of different scientific principles. Such principles addressed in this resource include air pressure, acid/base reactions, osmosis, inertia, density, forces, and architectural structures.
In this resource, students will demonstrate several scientific principles by exploring characteristics of an egg's material and shape that make it so versatile.
- Relate the strength of an egg to its structure.
- Use problem-solving skills in building solid structures.
- Describe the effects of an acid-base reaction.
Generally speaking, two of the main factors that contribute to the strength of a structure are its material and shape. This also applies to the material and shape of an egg.
Calcium carbonate, or CaCO3, provides hardness and strength to things such as seashells, rocks, pearls, coral reefs, and eggshells. Since calcium carbonate is a base, it is no longer used for building purposes on its own (in limestone form) because it dissolves in acid rain.
A good quality eggshell will contain, on average, 2.2 grams of calcium in the form of calcium carbonate. Approximately 94% of a dry eggshell is calcium carbonate. The remainder is composed largely of phosphorus and magnesium, with trace amounts of sodium, potassium, zinc, manganese, iron, and copper. Immersing an egg in an acidic solution, such as vinegar, will disintegrate its shell through a common acid-base reaction.
An eggshell is a natural example of an arch. Arches, even those made of eggshells, are strong because they exert horizontal as well as vertical forces to resist the pressure of heavy loads. The crown of an eggshell can support a heavy load because the weight is distributed evenly along the structure of the egg.
Although the egg is strong in compression, it is weak in tension. Chicks are not strong, but by poking with their beaks from inside the egg, they are able to break out of their shells. They break the shell using tension. To make a structure strong with a tension weak material, such as an eggshell, forces must create compression and avoid tension. Fortunately, the arch/dome shape of the eggshell fulfills these requirements.
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Science World at TELUS World of Science | School Workshop | Structures