How can you remove the hard calcium carbonate layer of the egg without damaging its semi-permeable membrane? Can this egg be inserted into a bottle with a narrow neck without distorting its shape? Explain the process involved.

Question

Philoid · Accepted Answer

1. The given experiment can be successfully done by using laboratory chemicals as well as household items. The process of osmosis is used in this experiment.

2. The hard calcium carbonate membrane can be removed without damaging the SPM by dipping it in a dilute mineral acid or vinegar for a few hours or overnight. On treatment with acetic acid/vinegar, the acids eat away the calcium carbonate and release calcium acetate and carbon dioxide.

3. After the shell has degraded, a soft, translucent egg is seen. It is placed in a hypertonic aqueous solution of sodium chloride, causing water from the egg to escape into sodium chloride and causing the egg to shrivel in size. The egg can easily be inserted in a narrow-necked bottle.

4. After inserting in a bottle, pure water is added to the bottle, which acts hypotonic to the contents inside the egg, causing water to flow through the SPM and returning the egg to the original shape. The shrivelling of the egg due to concentrated sodium chloride and swelling to original shape due to water is due to osmosis.

Use the diagram below to understand the experiment.