Why A Stale Egg Floats In Water


After my last post on Easter Eggs in Google Chrome I am back with yet another post on eggs! Looks like I am getting obsessed with eggs !! But this time the post is about real eggs.

You must be aware of a simple process of checking whether that egg you bought to have a delicious omelet is stale or fresh. For those who don’t know, well you just need to put it in a glass of water. Stale egg floats in water while the fresh one sinks. So far so good.

But have you ever thought why this happens? Ok let me give you a hint. One thing that should immediately come to your mind is density. Since stale egg floats while fresh one sinks, that means it must be lighter than the fresh egg.

Now that we know what track to follow, let’s go into more detail and see what makes stale egg lighter than fresh one. As with any other fruit or vegetable, eggs also undergo decomposition with time. (In simple words, egg rots just like any fruit or vegetable rots with time). During the decomposition process water vapor and some foul-smelling gases are released (now you know how the phrase “smells like a rotten egg” came), which comes out of the porous egg shell. Thus the size of the yolk and egg-white reduces, its place being taken by air, thus making it lighter. This makes stale egg float in water.

I found an interesting link showing how old an egg is depending on how it’s floating.

So next time when you get eggs from market, try this test out. By the way, you can also make a fresh egg float in water. Did you say ‘How’ ?? I’ll leave that for you to answer. You can leave your answer as comments below. No prize for getting the correct answer though smile_tongue.


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2 Responses to “Why A Stale Egg Floats In Water”

  1. Vlocker
    April 11, 2011 at 10:22 am #

    Just add common salt to make a fresh egg float! The salt will increase the density of water.

  2. einstein
    August 20, 2011 at 8:20 am #

    Just add common salt to make a fresh egg float! The salt will increase the density of water:)

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