Effect of Concentration on Osmosis

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Effect of Concentration on Osmosis

Aim

To find out how the concentration of sucrose solution affects the mass

of the potato chip left in the solution for one day.

Prediction

I predict that when the sucrose concentration is low the potato chip

will gain mass. This is because there will be a higher sucrose

concentration in the potato chip so water will go into the potato from

the solution. I predict that when there is a high concentration of

sucrose the potato will lose mass. This is because there is a higher

concentration of sucrose solution in the solution compared to that in

the potato chip so water from the potato will go into the solution to

even it out.

Osmosis is "the movement of a solvent through a selectively permeable

membrane (as of a living cell) into a solution of higher solute

concentration that tends to equalize the concentrations of solute on

the two sides of the membrane"

Osmosis is the movement of water from high water concentration to

lower water concentration through a selectively permeable membrane.

Selectively permeable membranesare very thin layers of material (cell

membranes are selectively-permeable), which allow some molecules to

pass through them but prevent other molecules from passing through.

Cell membranes will allow small molecules like Oxygen, water, Carbon

Dioxide, Ammonia, Glucose, amino-acids, etc. to pass through. Cell

membranes will not allow larger molecules like Sucrose, Starch,

protein, etc. to pass through.

In my experiment I will have a test tube with a potato chip in. The

outside wall of the potato chip is selectively permeable so it lets

water pass through it but not bigger molecules such as sucrose. In the

test tubes I will put different concentrations of sucrose solution.

When the concentration of the solution is lower than that in the

potato, water will pass through the selectively permeable wall into the

potato.

Potato cells

Sucrose solution

The mass of the potato chip increases

Sucrose molecule

Water molecule

When the sucrose solution is stronger outside if the potato chip water

will move out from the potato chip into the solution.

When the concentration is the same on both sides of the selectively

permeable wall nothing passes through it and the mass will stay the

same.

Plan

Apparatus

Five test tubes

Labels

Ruler

Scales

Tissue...

... middle of paper ...

...hips in each test tube. This would make it more accurate as when I

had two in a test tube if one of them was a long way out it made the

graph not follow the line well when I plotted the averages.

There was one anomalous result at 0.5 mol. I think this was because we

patted them dry when we got them out of the test tubes as we did not

want to weigh there water on the outside of the potato but I think

that we may not have dried them all equally so this anomalous result

may have been due to it having water left on the outside of it.

Also the potato itself was not from the same part of the potato and

was not exactly the same size, although I did try to cut them to 36mm

each.

I could also try the same experiment but with different volumes of

cell tissues and see if the percentage change differed with a bigger

and smaller surface area.

I could now investigate the smaller range near to 0.25 to see the

sucrose concentration equivalent to the potato.

Finally, I could extend the experiment to a more exact level by

looking at the potato cylinders under a microscope, then I would be

able to see the cells in greater detail and draw some more

observational results.

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