Investigation of Osmosis
Aim: - To investigate the effect of varying the concentration of sugar
solutions on the effect of osmosis between the solution and a potato
chip cells.
Apparatus: -
Potatoes
Watch
Sugar solutions (DI, 0.2, 0.4, 0.6, 0.8, 1Molar)
Distilled water
Mass balance
Knife
Measuring cylinder
6 petri dishes
Ruler
Prediction: - I think that the lower the concentration of the sugar
solution in the petri dish the larger the increase of the mass of the
potato will be. This is because the water molecules pass from a high
concentration to a low concentration of water molecules through a
semi-permeable membrane. The chips in higher water concentrations will
have a larger mass than in higher sugar concentrations.
My graph may look like this:
[IMAGE]
I think this is going to happen because of the following scientific
knowledge:
Scientific Knowledge: -
Osmosis is the movement of water molecules to a lower concentration of
molecules through a semi-permeable membrane. The water will move in
different ways in different solutions. This will make a chip increase
and decrease in size. After osmosis takes place the chip will become
plasmolised
In a high concentration of water the amount of sugar is low. This
could be called a weak or dilute solution.
In a low concentration of water the amount of sugar is high. This
could be called a strong or concentrated solution.
When two solutions are divided by a semi-permeable membrane the water
will move from the area of high concentration to the area of low
concentration, until both sides are equal (have reached equilibrium).
[IMAGE]
This can be seen in living cells. The cell membrane in cells is
semi-permeable and the vacuole contains a sugar solution. So when a
cell is placed in distilled water it will move across the
semi-permeable membrane into the cell by osmosis, making the cell