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The 'chip shop' problem

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The 'chip shop' problem Mr and Mrs Brown, who run and own their own chip shop, are very concerned as they are getting complaints. The complaints are towards their employee lee, who sometimes prepares the chips soft and limp. Mrs Brown does not want to sack him as she says sometimes his chips are perfectly satisfactory. The question I am faced with is why are the chips sometimes unsatisfactory? Apparatus * White tile * Forceps * Small test tubes x 12 and lids * 1 or more large potatoes (from the same batch) * A 500 ml beakel of distilled water * Sticky labels * A 500 ml beaker l mole of salt solution * Teat pipette ( 3 cm3 ) * (Paper towels on the side ready) * Measuring cylinder ( 25 cm3 ) * Cork borer * Stopwatch * Top pan balance Variables Independent- The salt concentration Other variables that could of efreccted the rate of osmosis were- the size of the chip we used which was kept at 4 cm, depending on how big the chip was they could contain a HIGHER or lower concentration. Also the temperature, which was at room temperature. The variety of the potatoes. The amount of chips per tube. The size of each test tube. These are all the variables that I decided to keep constant. Dependent- Length of the potatoes Mass of the potatoes The angle of dangle Out of these three I will be measuring the length and mass. Diagram of test tubes once ready Volume of Distilled water (cm3)- 20 16 12 Volume of 1m salt solution (cm3)- 0 4 8 Volume of Distilled water (cm3 )- 8 4 0 Volume ...read more.


the change in mass is a positive number. This then tells us that the potato increases in mass by 33.5 %. But then once there is 20 % salt solution present the potato cylinder no longer increases in mass by a large amount but only by 2 %. As soon as the concentration of salt solution is 40 % the cylinder begins to decrease in mass by 9 % and that is why it is shown as a negative number. The cylinder decreases in mass at a steady rate until the salt solution is at 80 % where the rate begins to slow down. Then at 100 % concentration of salt solution instead of cylinder continuing to decrease in mass further, the percentage change is actually smaller than at 80 %. With the change being 21% rather than 24%. We can see from the graph that the point of change for the cylinder is when the concentration of salt solution is 24 %. This is where the cylinders mass is no longer increasing but begins to decrease in mass. There is a very big change made at the concentration going from 0 % to 20 %. The mass changes from increasing by 33.5% to only 2 %, this is something that I will need to take into consideration. As I did not think this would happen and did not state it in my prediction. concentration of change in mass Salt solution (%) % 0 33.2 20 2.7 40 9.45 60 19.6 80 23.5 100 20.9 A graph to show the percentage change in length Against the concentration of Salt solution What the graph tells us The trend in this graph is a lot like the graph showing mass. ...read more.


I found their change in length to only be 3mm when they should have been approximately 6mm. however these anomalies were all accounted for and were not used for further calculations. (Refer to the results table where they are all clearly highlighted) In the Future In future I can help to prevent these anomalies by instead of doing two experiments do three or four which will then give me a bigger range of results to compare with. As a further point I could also measure the 'angle of dangle', which may help come to a final conclusion. By using the angle of dangle it would have been a more accurate way to say how soft or limp the chip was. It would have allowed me to see how limp the chimp was by accurately seeing the angle at which it bent, another option that may not be as accurate would be to as I did in my preliminary tested the hardness of the chip simply using my fingers The experiment did give enough evidence to support my conclusion, because the two main factors were found, length and mass. I must take into consideration the reliability of my results and my final conclusion, so a lot research needs to be done in order to prove this. Apart from using biology textbooks which help me to compare my theory. I have compared my conclusion with other students in my class. I found that we all have the same trend and pattern in our graphs, which led to an accurate conclusion. When comparing with other students I had to take into consideration that they may have some anomaly results, so not to take their results as an perfect example. So to overcome this I used six students' results. ...read more.

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