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Osmosis demonstration
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Osmosis demonstration

In biology, the osmosis effect can be demonstrated in a number of ways. In schools, there is a standard apparatus for demonstrating osmosis with visking tubing. However, osmosis can also be demonstrated using household ingredients, as described below.

Table of contents
1 Demonstrating with eggs
2 Demonstrating osmosis with Potato slices
3 See also

Demonstrating with eggs

An egg contains a semipermeable membrane underneath the shell, which can be used to demonstrate osmosis. The eggshell is mostly made of calcium carbonate which will dissolve in acid. Vinegar or hydrochloric acid are suitable. Stronger acids will dissolve the shell faster, but are more corrosive. Vinegar takes several days.

Method

You will find that the egg in water will have swollen considerably. If you carefully pierce the membrane with a needle a jet of water will shoot into the air. The egg in an isotonic solution will be approximately the same size, while the egg in 1M solution will have shrunk.

Demonstrating osmosis with Potato slices

There are a number of variations on this demonstration. Potato slices can be used, as also can raw potato 'chips' (English) or 'French fries' (American). Consistancy of sample can be ensured by using a commercial potato chipper, or by using a cork borer of selected diameter. Other vegetables or fruit may, of course, be used. The changing dependent variable may be weight or length.

Materials

Note: Ensure that the cork borer or chipper will cut chips or cylinders which fit into a standard test tube

Method

See also