The Lab Report. The rate of ossmosis and the surface area.

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Ms. C. Evans

Biology Lab Report


To determine the effect of surface area on the rate of osmosis.


The main aim of the experiment was to determine the effect on the rate of osmosis by the changing surface area. The changes were observed in the masses and surface area of the chopped potatoes which were initially of different surface area but same mass. The rate of osmosis increased with increase in surface area. And this increase in the rate of osmosis was directly proportional to the surface area.


Now the rate is given by the change over time. Well the osmosis is the movement of water molecules from high concentration to a low concentration; and of course a semi-permeable membrane is required for keeping the concentration difference. So it's the movement of molecules of water along the "concentration gradient (from high to low concentration)" through the semi-permeable membrane. So the rate of osmosis is "change in concentration(moles) /time(seconds)"

Now the concentration is given by "moles/liter". And the moles are "mass(gram)/molecular mass(grams)". So the moles are directly proportional to the mass of the substance. So the rate of osmosis could even be written as "change in mass(grams)/time(seconds).


Three beaker (200 ml each)


Fries maker.

A knife.

Distilled water (at room temperature).

A Clock.

Weighing machine.

A tong (to take the potatoes out of water)

Brown paper.



All the three beakers were cleaned and dried. Then the equal amount (i.e. 200 ml) of distilled water was poured in each beaker. The water in all the beakers was at room temperature. This was done so that the effect of temperature on the rate of osmosis could be negligible. Then the potatoes were chopped with the French fries maker and 3 pieces of chopped...