The type of potatoes I will use is going to be kept the same, because different potatoes may absorb at different rates. For this experiment I am going to use the same potato.
The time the potato chip is left in the solution must be kept the same for each chip. This is because more or less solution may be absorbed depending on time. I am going to keep each potato chip in each solution for nine days.
The surface area of the potato chips will be kept the same by having all the chips the same size. This must be kept the same because the amount of surface area exposed to the solution may effect the rate of osmosis. The thickness of the chip will already be the same, so I will cut the length of each chip to 3cm long. wwdb dbw esdbdbs aydb dbba ndb kcdb dbuk.
To make the mass readings more fair, I will take each chip, roll the chip gently on a paper towel, to remove all excess solution, and I must not squeeze the chip. DzIlh12 Visit essaybank fa co fa uk fa for more fa Do not fa redistribute DzIlh12
I am also going to use the same balance to weigh my chips. This is because the measurements may vary slightly between scales.
I predict that the higher the concentration of salt in the solution, the more water will move out of the potato chip. We know that osmosis is the flow of water in a solution through a membrane while the other molecules are unable to pass through the membrane. Experimentation is needed to discover which membranes allow osmosis, as not all membranes act in this way. Some membranes may allow all or none of the molecules of a solution to pass through, only a few may allow a selective flow. The cell membrane of the potato is partially permeable (it lets some substances in but not all substances). This means that water particles can diffuse into the cells, via osmosis. This occurs if the cells are surrounded by a weak solution e.g. Vimto. If the cells are surrounded by a stronger solution, e.g. very salty water, the cells may loose water by osmosis. wwgg ggw esggggs aygg ggba ngg kcgg gguk;
To ensure safety, I will keep my boiling tubes in a large glass beaker so they cannot fall over. The potato chips will be carefully cut on a white tile using a scalpel, so that no one will be cut. wwba baw esbabas ayba baba nba kcba bauk.
My experiment is not testing how permeable the chip´s membrane is, but it is testing the rate of osmosis of the salt solution. I am predicting that the higher the concentration that the chip is exposed to, the more water will move out of the chip; making it flaccid.
I am going to set up the experiment so I have three results per concentration, I will then take an average to make the test fairer. One result may not be accurate because of human error, so to get rid of the errors, I will repeat it. I will also do at least 3 types of concentrations, to have enough results and to see if my prediction is correct. I am probably going to do 4, these being;
- Water
- 3 x 2g salt
- 3 x 3g salt
- 3 x 4g salt
The equipment I am going to use will be:
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- A chipper
- A white tile
- A scalpel
- 10 boiling tubes
- A large beaker
- A measuring cylinder
- A large potato
- Salt
- Water
- Weighing scales
Preliminary Results
My preliminary results were a bit rubbish, as I could not really think of anything to do except find out how many spatulas of salt or sugar went into 25ml of water. However these are my results: wwfa faw esfafas ayfa faba nfa kcfa fauk.
Sugar into 50ml water = 15 spatulas
Salt into 50ml water = 15 spatulas
Although pointless I did decide that sugar took longer to dissolve into the water, so would I use salt instead (to save time). I also decided my concentrations. ( I do not understand the language used when talking about concentrations i.e. molars etc. so I will use ratios instead )
The ratio is water (ml) : salt (g) and the letters are what I labelled the boiling tubes as. wwae aew esaeaes ayae aeba nae kcae aeuk!
A 25 : 0
B 25 : 2
C 25 : 2
D 25 : 2
E 25 : 3
F 25 : 3
G 25 : 3
H 25 : 4
I 25 : 4
J 25 : 4
I am going to measure the weight of the chip (before and after) to the nearest .01g (the nearest the scales will allow)
Obtaining Evidence
Here is my table of results:
Tube Salt Mass Before (g) Mass After (g) Change in Mass (g) Change in Mass %
A 0g 5.25 5.13 -0.12 -2.339181287
B 2g 5.16 4.52 -0.64 -14.15929204
C 2g 5.42 4.62 -0.8 -17.31601732
D 2g 5.61 4.83 -0.78 -16.14906832
E 3g 5.99 5.16 -0.83 -16.08527132
F 3g 5.68 4.74 -0.94 -19.83122363
G 3g 5.71 4.78 -0.93 -19.45606695
H 4g 6.15 5.25 -0.9 -17.14285714
I 4g 6.01 5.74 -0.27 -4.703832753
J 4g 5.72 4.92 -0.8 -16.2601626
Average 2.7g 5.67 4.969 -0.701 -14.34429734
The average for 2g salt is –15.875
The average for 3g salt is –18.458
The average for 4g salt is –12.702 from www.essaybank.co.uk
Analysis
My first graph is just there to show comparisons between the mass before and the mass after. This is quite useful, as it shows that the chips with 2g salt lost around the same mass, whereas with the chips in 3g salt G and F lost more mass than E.
The second graph shows the change in mass of the chips. In theory this graph should be quite useful as I can guess the change in mass of the chip that has 5g salt in the water. However this will probably not be happening with mine, as it is quite wrong. I don´t know if my results are wrong or not, but the graph looks very wrong. From the graph I have noticed that I have one anomalous result per gram of salt. B, E and I are all anomalous, and this changes the bottom line of the graph, but the top two still look dodgy. If J had a .87g change in mass (or a figure around .9g) then the top two lines of the graph would have been quite good. wwag agw esagags ayag agba nag kcag aguk: wwcf cfw escfcfs aycf cfba ncf kccf cfuk.
Evaluation
The experiment was easy to do, but all the results I took had to be accurate. Unfortunately I had to change my plan several times. There are several reasons for this, these being that someone stole my boiling tubes, which I had spent 2 weeks getting exactly the right amount of salt into. There were also other things, like having the chips 5cm long. I changed this to 3cm because I couldn´t find 10 5cm long chips. Also, I changed the amount of solution I would keep the potato chips in, because otherwise the water spilled out of the tube, and I only needed enough to cover the chip (it was 100ml). These changes were easy to make, as they were only minor, however the case of the stolen boiling tubes meant that I had to spend several lunchtimes taking my results again. wwbf bfw esbfbfs aybf bfba nbf kcbf bfuk;
I think I took enough results for the coursework. The range was big enough, but to fill in the gaps in my graph I could have taken different results, i.e. 1g, 1.2g, 1.4g etc. or even smaller. This way I could have found more accurate results. Also to make my experiment better I could have repeated it more, and possibly have worked with someone, as I was working on my own, or even with the whole class. I could have also cut the potatoes into doughnut shapes, because the cells in the middle of the potato might have different properties, making them react differently to osmosis. I could have also used a machine to cut the potato chips. I could also weigh each chip on a digital and more accurate scale, e.g. not to 0.00 but to 0.0000g. btrYahz9u from btrYahz9u essay btrYahz9u bank btrYahz9u co btrYahz9u uk
There was one main anomalous result, this is highlighted in red and is two sizes bigger (tube I), but there is one more, but it is not that far out (tube B). This may have been caused by human error, or one out of my ten results might have been inaccurate, and changed the average. Or perhaps the chip was not cut accurately, or I added the wrong amount of salt. concentration. wwed edw esededs ayed edba ned kced eduk.
I could extend my coursework by testing the same brand of chip using a different substance. By this I mean using a different thing instead of salt, i.e. sugar or coffee or even vimto. Then I could find out whether osmosis occurs differently with different things diluted in the water. I could even use different vegetables.
