Saturday, September 29, 2012

Expanding Egg/Shrinking Egg Experiment

First we soaked our raw egg in the vinegar for 72 hours.  We noted the chemical reaction of the acid with the calcium carbonate of the shell.  The bubbles we discussed were from the carbon dioxide being produced through the chemical reaction. 

Our egg expanded and became much larger then it started.  We talked about the semi-permeability of a cell.  Our egg became rubber-like outside and we discussed how it felt as we handled it.  Sarah squeezed and even bounced it in the sink several times before it finally popped!   We talked about the protective nature of cell walls and how God designed them to protect the cells.  We talked about how the membrane of this egg acted as a cell wall would and provided some protection to the egg from bursting as we tossed it around for a while.  

After it burst it had a fairly intact membrane that was very rubber like in it's feel and gave a great visual for the protective layer of a cell membrane.  
Next we took an egg we had soaked for 72 hours in vinegar as above but then we had placed that egg in corn syrup for 72 hours.  The egg shriveled and "shrunk" instead of expanding and growing big/rubbery.  We discussed semi-permeability of cells and how this egg's membrane could not pass the larger sugar molecules through it's membrane but the water could easily move out of the egg membrane - causing it to "shrink".  

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