Why does it take more salt to float a hard-boiled egg than it did to float a raw egg?

Question

I boiled 2- three cup containers of water. It took 5 tablespoons of salt to float my raw egg, but it took 9 tablespoons of salt to float my hard-boiled egg. Suspicious...

Please tell me why!

Thanks a million in advance and God Bless,
Sameeh

Answer 1

I believe it is due to the air bubble. There is an air bubble at the end of the egg, and when you cook the egg proteins, they denature, which causes them to expand and thus take up more space. This space has to come from somewhere, and the air bubble gets squeezed to a smaller size to accommodate the expanding protein mass. The smaller air bubble means the egg's average density goes up, even though it's weight essentially remained the same. Fish squeeze and relax their swim bladders for the same purpose, so that they can float up or down easily in their watery environment.

Answer 2

This is the physical reason, though it doesn't explain exactly why (the chemistry):

For some reason they have different densities. If they are the same size, then the hard-boiled egg must have more matter inside it. Perhaps they started out with different densities before the boiling, like they were from different types of hens. Perhaps they started out with different amounts of the yolk and white. If they had the same amount in them, then perhaps the raw egg is slightly larger than the other one, so it is less dense. Perhaps hard-boiled eggs absorb water when they solidify.

A good experiment might be to try it with the same egg - to float it when it is raw, then hard-boil it and try to float it then.