The Solute Concentration of a Potato

The Solute Concentration of a Potato

To find out what the solute concentration of a potato is,

this shall be done by finding out the effect of Osmosis on a potato.

Prediction: That if there is more water outside the potato than

inside, the potato will increase in size. If however there is less

water outside the potato than within, then I shall expect the potato

to shrink in size. I think this because of the laws of Osmosis.

Osmosis is the diffusion of water through a partially permeable

membrane from a high concentration gradient, to a low concentration

gradient.

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When there is a situation, such as above, the big particles on the

right cannot fit through the partially permeable membrane. However the

smaller water particles can fit through, and so they spread out to

even the pressure, and spread the concentration equally. As shown in

the diagram below:

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If we say that the right hand side in picture 1 is the potato, and the

left hand side is the beaker of sucrose-water solution, then if there

is more water in the left hand side (as there should be until we are

using 0.6m solution) then the potato should increase. If there is more

water on the right hand side (as there should be from 0.6m solution

onwards) then the potato should shrink, as water leaves the potato and

enters the beaker.

Scott Bissett 10B

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Apparatus: Corer, Knife, Tile, Potato, Measuring cylinder (10ml), 8

test tubes, Distilled water, Sucrose, Ruler [IMAGE]

1.

Method:

Core the potato 8 times.

2. Cut each core into lengths of 3cm

3. Make sure there is no potato skin on the cores

4. Fill a test tube with 10cm³ of distilled water (0m)

5. Fill another test tube with 9cm³ of distilled water, and 1cm³ of

sucrose (0.1m)

6. Fill another test tube with 8cm³ of distilled water, and 2cm³ of

sucrose (0.2m)

7.