Naked Science Forum
General Science => General Science => Topic started by: baby2michaelt on 04/03/2004 14:07:47
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me and my fiance are doing a science fair project on floating eggs and we were wondering what causes salt to make eggs float. And is there a site that explains this reaction
baby2michaelt[}:)]
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I think that if you put salt in water its density changes. So if you have a very salty solution, it has a higher density than water.
If the solution is high density, the upthrust required to equal the volume of water displaced is less and so the egg floats higher.
I.e. eggs "float" or sink less, when the solution is denser, and the solution effectively "sinks" to the bottom of the beaker, preferentially.
How dissolving the salt changes the density is another question though!
Pipster [:I]
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i guess tht that is the reason that it takes ten teaspoons of water to make an egg float
thanx[:D]
baby2michaelt[}:)]
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Hello Everyone!
The water changes density because salt molecules are hevier than Water molecules. Observe:
Relative Mass H20 (Water) = 18
Relative Mass NaCl (Common Salt) = 58.5
If salt was less Dense than water would the density of the solution decrease? Don't Know.
I Love Caesium!!!
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I heard that rotten eggs float even in non-salt water. Is it true?
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I heard that rotten eggs float even in non-salt water. Is it true?
I believe this is true. The reason is that decomposition processes inside the egg convert the higher-density proteinaceous and fatty material into gases; the overall effect is to reduce the density of the egg so it floats, a bit like a submarine emptying its tanks of water to make it surface.
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As @chris says its the gasses that do it and they tend to form an air sac at the large end between the shell and membrane. So a fresh egg will sink and lie horizontally on the bottom and as the eg ages the large end will gradually lift until the egg is floating large end up. Sometimes the air sac will move so a small % of eggs will float horizontally or small end up.
Eggs that are lifting off the bottom are usually ok to eat if well cooked eg hardboiled, infact, because of the separation of membrane and shell older hardboiled eggs are easier to peel.
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I heard that rotten eggs float even in non-salt water. Is it true?
I believe this is true. The reason is that decomposition processes inside the egg convert the higher-density proteinaceous and fatty material into gases; the overall effect is to reduce the density of the egg so it floats, a bit like a submarine emptying its tanks of water to make it surface.
Thanks for your confirmation. I just remember a egg-peanut (baked egg-covered peanuts) commercial in my country. It told about a peanut who wanted to cross a river but couldn't swim. An egg then offered his help to the peanut, giving him a piggy-back ride while he is floating. I couldn't help but saying "Aren't eggs that float rotten eggs?".