OSMOSIS DIAGRAM:
HYPOTHESIS.
I predict that as the water concentration increases the length and weight of the potato chip will decrease. I believe this because the higher the concentration of the glucose solution the lower the concentration of the water. When the potato chip is put into the solution, it will, by osmosis lose some of it’s water and the water will defuse into the solution of glucose, causing the potato chip to lose water which means that it’s weight and length will decrease.
However, if a potato chip is placed into a solution of 0 molar concentration it should gain weight and length. This is because the solution has more water potential than the potato chip and so water moves from an area of high concentration (the solution) to an area of low concentration (the potato).
METHOD.
For organisation we set up all out apparatus first. We set up 7 petri dishes labelling them individually to avoid confusion whilst taking readings. We filled the petri dfishes with the right concentrations of solution beginning at 0m and working up all the way to 1m. In order to try and make this a fair test we added the potato chips (which were already cut to size all at about 33mm and weighing around 1 gram) as quickly as we could so that one potato chip didn’t have any longer than the others. We left each one for around 30 minutes. After 30 minutes we emptied the petri dishes leaving only the potato chip inside. Before measuring and weighing each chip we put them onto a paper towel to remove any excess water that were on them otherwise the results would not be as accurate as they could be. We then measure the chips in mm as this is a more accurate measurement and weighed them in grams.
FAIR TEST.
This experiment will have to be kept as fair as possible otherwise the results would not be accurate enough. There are many thing that must stay the same. The room temperature, the size of the potato chip as it goes into the solutions, the time the potato is left in for and also the way of measurement or weighing at the end. The only thing that will change during the experiment is the concentration of the sugar or water solution.
ANALYSIS OF GRAPHS.
Average change in length.
This graph shows me that the higher the concentration the more length the potato will loose. As concentration increases, the length decreases. In this graph I had many negative results. This shows that the length is strongly affected by osmosis.
Average change in weigh
The results for average change in weight is quite confusing. For example the result I obtained for 0,1 molar concentration does not follow the pattern of the others. It is not possible that the weight could have gone up more for 0.1 molar compared to 0 molar. This could be due to having excess water on the potato chip or having misread the scales.
CONCLUSION.
To conclude this investigation on osmosis I can say that the movement of water through a selectively permeable membrane is affected by the concentration of glucose solution, or by any other solution. The higher the concentration of glucose solution, the more the potato chip will loose it’ s length and weight.
Because water molecules have kinetic energy, they are constantly moving around in gaseous or liquid formation, moving randomly from one place to another. The greater the concentration of water molecules in a system or solution the greater the total kinetic energy and the higher it’s potential. This means that as the concentration of glucose increases in a solution, the concentration of water decreases lessening the waters potential and lessening it’s ability to move between solutions by osmosis. Relating this to the potato chip basically, as the concentration of glucose in each solution increases the water in that solution is less able to move to the potato, causing water from the potato to move to the solution, decreasing the length and weight.
EVALUATION
When it came to accuracy during this investigation it wasn’t that easy. Having to keep things such as weight and length the same sounds quite simple but when you put this in to practice it doesn’t work out quite the same. Even if you cut all potato chips to the same length it was very unlikely that they would all weigh the same.
Another thing that I thought was not done very well was when we pulled the potatoes out of the petri dishes we had to dab them with a paper towel in order to remove some of the excess water but by doing this we could not be sure that we wernt removing any water that was not excess. Some of the results were anomalous and therefore something must have gone wrong somewhere. If I were to do this investigation again I would perform the experiment more times before hand so that when it came to the real one I would have more experience in knowing what do do and what not to do in order to keep the results as fair as possible.