My aim is to find out the effect that different solutions (water, sugar solution, salt solution) have on the process of osmosis on a potato chip. To measure this change I will use a scale that measures in (g).

I will firstly begin by collecting my equipment, which is listed below:

3 test tubes

3 measuring cylinders

Scalpel

Cutting board

1 King Edward potato

Potato extractor

Test tube rack

Pure water

Salt solution (1M)

Sugar solution (1M)

Balance

Once all my equipment has been gathered, I will get the potato and using the potato extractor I will extract 3 pieces of potato, which I will then cut into small chips, which will be approximately the same size, using a scalpel. Then I will weigh each piece on the scale and take down the reading onto a table, which I will have designed. Then I will measure the solutions in the measuring cylinders, which will then have 5ml of each solution. After I will pour these solutions into the test tubes, which I will then follow by putting the potato chips in. I will take my first set of results after 3 hours and the second reading after 6 hours. I will take these readings by removing the potato chips from the test tubes and drying them gently with a soft piece of tissue and then weigh them on the scale and write my results onto my table. The potato chips will then be replaced into the test tubes and the same process will be repeated after 6 hours. After collecting these results I will work out the change in weight and see whether it was an increase or a decrease, and with that I can workout the percentage change in weight.

Below shows the tables in which I have recorded my results.

Weight Before

st Results

Change In weight

% change

King Edward In Water

.65g

.79g

+ 0.14g

9%

King Edward In Salt

.63g

.29g

- 0.34g

21%

King Edward In Sugar

.69g

.2g

- 0.49g

30%

In the table above I show the results for my first reading, which was taken after 3 hours of the potato chips being exposed to the solutions. Also it shows the change in weight from when the potatoes were first weighed to when the reading was taken. And from that I was able to calculate the percentage change, which is necessary, as all the chips did not weigh the same to begin with.

Weight Before

2nd Results

Change In weight

% change

King Edward In Water

.65g

.84g

+ 0.19g

2%

King Edward In Salt

.63g

.23g

- 0.4g

25%

King Edward In Sugar

.69g

.19g

- 0.5g

30%

In the table above I show the results for my second reading, which was taken after 6 hours of the potato chips being exposed to the solutions. Also it shows the change in weight from when the potatoes were first weighed to when the reading was taken. And from that I was able to calculate the percentage change, which is necessary, as all the chips did not weigh the same to begin with.

From my results and graphs I can see that my prediction was correct. The potato chips in water absorbed more water making it turgid, and the potato chips in salt and sugar solutions became flaccid, meaning they lost weight. I have plotted my results onto a bar chart because it is visibly easier to interpret the results. The charts show that after 3 hours of the potatoes having been in the solutions, that the one in water had increased in weigh this because there was less water in the potato than in the surrounding test tube so the water in the test tube was transferred through the semi permeable membrane and into the potato chip. The potatoes in salt and sugar solutions decreased in weigh because there was more water (moisture) in the potatoes than in the solutions so the water transferred from the area of higher amount of water which was the potato to the solution which was of a less amount, and that made the potato decrease in weight. After 6 hours I could see that the potato chip in sugar solution was nearly the same as the results recorded after 3 hours, this is because the potato had already been extracted of its moisture (water) and no more could be extracted as there was none left, this tells us that when a potato chip is put in sugar solution it takes 3 hours or less for osmosis to occur. The potato chips in salt solution carried on decreasing in weight, showing that there was more water to be extracted from the potato. The potato chip in water continued to increase in weight and it would have done so until there was no more space in the potato to allow more water to enter through the semi permeable membrane.

I think that the experiment went well over all, there were no complications when doing the experiment and all went according to plan. I think that I did not collect enough results and I should have collected more, then I could have a larger view of the process of osmosis. Although with the results I gathered it was enough to make informative charts. Some of the precautions I took when conducting my experiment was to ensure that the variables, which I was not changing, were always the same. Whilst cutting the potato, extreme care and precision had to be taken with the scalpel, as it is very sharp and could easily cause a serious wound. When recording the results I had to make sure that I wrote the same reading as the one given by the scale. I had to ensure that every time I handled the potatoes my hands were clean and dry. This was to stop any kind of contamination and to make sure that I did not pass on any extra water onto the potato. If I were to repeat the experiment I would change my independent variable, as it was quite difficult changing the solutions. If I were to improve the experiment I would make more solutions available for testing and I would give myself more time to collect more results.

Lawrence Ireton

Year 11