Plants draw water from the earth by osmosis. And food gets into our cells by osmosis. What is osmosis and what does it have to do with cooking?
Things Required:
3 large raw potato cubes of the same size
3 glasses of water
A ruler
Salt
Directions:
Put each cube into a glass of water. To glass number 1, add a large handful of salt. To glass number 2, add a pinch or two of salt. Leave glass number 3 plain.
After an hour, measure the potato cubes.
This Is What Happens:
Number 1 will be smaller than it was; number 2 will stay same size; number 3 will be a little bigger.
Science Behind It:
The more salt you add to the water, the stronger the mixture (the solution) becomes. The stronger the solution, the lower its concentration of water.
Osmosis is the flow of a liquid through a membrane (a thin wall). The liquid will always flow into a stronger solution-one where the concentration of liquid is lower.
In number 1, the potato cube shrinks as the water in it moves from the weaker potato juice into the (stronger) heavily salted water. In number 2, where the concentrations are equal, there is no movement. In number 3, the potato juice is the stronger solution, so the water moves into its tissues and makes the cubes swell.
