Re: What would cause a 10% or 25% concentration of sucrose to diffuse into egg?

I'm not sure I know what you mean when you say, "we disintegrate the egg shell". I'm going to assume that you mean that you did something to dissolve the hard material of the shell, and what you were left with was an egg with just a soft membrane around it.

The idea of this experiment was probably to demonstrate osmosis, which is the diffusion of water from areas of high concentration to areas of low concentration. Assume for the movement that the soft membrane of the egg allows water molecules to pass through, but not other molecules such as sucrose or protein. Now assume that there is nothing but pure water inside the egg. In this case, the concentration of water inside the egg (100%) is greater that outside the egg, where there is a solution of sucrose. By osmosis, water should tend to leave the egg, and the weight should decrease.

There are a few reasons why the situation in your experiment is more complicated than what I've just described. First of all, the stuff inside the egg isn't pure water. There may not be any sucrose in the egg, but there are certainly lots of other things, such as protein, dissolved in the water that's inside the egg. This stuff will all contribute to the 'osmotic strength' of the solution inside the egg. So it is possible that the osmotic strength of the solution inside the egg is greater than the outside the egg, causing water to tend to diffuse in.

Another possibility is that the assumption that sucrose cannot pass through the membrane is incorrect. Proteins are MUCH bigger molecules than sugars, such as sucrose. So it is conceivable that the membrane will allow water and sucrose to pass through, but not protein. In this situation, sucrose would tend to diffuse from and an area of high concentration (outside the egg) to an area of low concentration (inside the egg), resulting in an increase in mass.

There are actually a number of other possible explanations, which you can dream up if you think about it a little. The only way to determine which hypothesis is correct is to carry out some further experiments. Good luck!

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