How Do You Make an Egg Float in Salt Water?


Quick Answer

Four tablespoons of salt thoroughly mixed into a drinking glass full of water is enough to float an egg. Adding the salt gradually while the egg is already in the water allows the sunken egg to float to the top slowly.

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Full Answer

Eggs sink in regular water because the density of the egg is greater than the density of the water. This means that there is more matter in a raw egg than there is in the same volume of water. Adding salt to water adds more matter to the water thus increasing the density and eventually allowing the egg to float. This is the same principle that allows objects to float on naturally salty bodies of water, such as the Dead Sea.

A well-known test for bad eggs uses the principle of density. A good egg that is fit to eat sinks to the bottom of a container of water, while an egg that is slightly old but still fit for hard boiling or baking may bob a bit in the water. A spoiled or rancid egg floats to the top. This is because as the egg ages, bacteria enter through pores in the shell. Respiration of those bacteria cause gas build up inside the egg, decreasing its density and making it more buoyant in water.

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