The difference between the water concentration in the potato and the 0.9 molar solution of salt is large; the water in the potato should be transferred from the potato, through the permeable membrane, to the solution surrounding the potato. As a result, I am sure that the weight of the potato will increase. As the potato tissues are surrounded by a stronger solution, it will probably become smaller, and shrink. But because of such high molars of salt, the water can diffuse all the way, throughout the two substances, equalizing the concentration gradient of the two substances.
My theory in this experiment is: due to the difference in the water concentrations of the two substances, I believe that the weight of the potato will decrease when it is tested with salt solution and increase when tested with distilled walter. By researching information about osmosis, and doing a preliminary experiment, I believe the graph would look something like this:
Fair Test:
Fair testing should play a big part in this experiment. If this experiment isn’t a fair test, it will give the wrong results, which could lead me to the wrong conclusions.
First of all, and most importantly, I will have to get the measurements and the weights of the solutions and the potatoes as exact. I will try and get the measurements of the potatoes as accurate as possible for every single potato, evenly cutting the potato pieces, and making a record of the length to the nearest millimetre. I will also be using a very sensitive balance so that I can get the best readings possible.
When using the balance, I will make sure that the balance is reading zero before I put the 5 potatoes on it. After the experiment, I will measure the 5 potatoes and take a reading to the nearest 2 decimal places.
I will also be reading the measurements of the measuring cylinder by reading the bottom of the meniscus.
Carrying out the experiment in a constant temperature is important. To avoid temperature change, which might affect the results, I will take the temperature of the solution into account. I will keep the experiment at room temperature at all times.
Getting and experimenting with the exact measurements of molars and water is vital. If the volume of one solution in a test tube is higher or lower than another, it will affect the results.
I will also make sure that the potato is fully covered by the 5 different kinds of solutions. This is because, if the potato isn’t covered up by the solutions, the effect of osmosis might not occur to its fullest.
Safety:
Safety is an important aspect in every experiment, even if the experiment seems harmless. That is why I take this into consideration, no matter what.
I will be using a very sharp knife, which could injure someone if it’s not handled properly. And I will also be careful that the solutions don’t get into our bodies internally.
Method:
There will not be any control for this experiment, as the weight would vary depending on the potato pieces. Therefore, it might affect the results, which I am going to take into account after the experiment.
First I will have to get the pieces of potatoes ready. The potatoes have already been cut into roughly the same size chips. I will use a scalpel and ruler to make sure they are all the same size and length. I will have 5 sets because I will have to test the potatoes in 5 different types of solutions; 0.2, 0.4, 0.6, 0.8 molar solutions of salt, and distilled water.
I will weigh each set and have them ready for us to put into the test tube.
Then I will put the 5 sets of 5 potatoes in the 5 different test tube . After a period of time, I will take all of the potatoes out of the test tube, so that the actual osmosis action stops, and I will put the potatoes onto paper towels to soak up any excess solution. I will then weigh and measure the potatoes taking in the average reading of the 5 pieces.
I will repeat the experiment so that I can make sure that all our results are similar, and so that I will be able to take the average of the 5 experiments. This makes sure that I get accurate results. Repeating the experiments is important, because I will be able to receive valid results, and look for any strange results.
Table of results:
Conclusion:
From my results I have found that they support my original hypothesis. The potato chip increased in mass with dilute solution, and decreased in mass in a more concentrated solution. The results were uniform and there are no readings which seem to be wrong or strange. The weights of the chips before the experiment ranged from 5.12g to 5.78g, this shows me that the potato pieces were cut precisely, and I believe they were accurate enough. There were, I believe, no anomalous results after the experiment as the weights were very similar in their own category. This tells me that my experiment was successful.
The graphs and the results show that:
Osmosis actually took place in the experiment.
As the molars increased, the percentage of the weight difference decreased.
Evaluation:
I followed the plan correctly and I believe I gained accurate and sufficient enough results to conclude the experiment, and to prove my hypothesis.
My final results were very reliable, due to the precautions I took to make this a fair test.
To make this experiment better, I believe that timing of the experiment could have been more accurate. I could have done one test at a time, so that I could reduce the time difference. Repeating the experiment would have given a more accurate average, but I believe that it is not necessary as the results were accurate.
Using more types of molar sucrose solutions would have helped me obtain better and a wider range of results, and more accurate results. Also, experimenting with one set for a longer period of time, for each set, would give me better results, because the osmosis action would reach its maximum, and therefore tell us how much water could be transferred for each solution.
Overall I think this experiment turned out to be very successful, and I’m very pleased with my results.
