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Does the concentration of a solution affect osmosis? -- A* - page 4
Keywords: Biology Osmosis Concentration Sucrose solution
By georgie1 on 31/12/2009
Level: GCSE Key Stage 4 (Years 10-11)
Page Number: 4 of 10 pages: 1 2 3 4 5 6 7 8 9 10and the surface area is small enough for osmosis to have a noticeable affect. My preliminary experiment also showed that over the period of 20 minutes, there was very little mass difference so by completing a second set of results in my final investigation that leaves the solutions for 48 hours; I will be able to see how osmosis is also affected by time. I will blot the potato cutting as much as possible to gain the maximum change in mass for more precise results.
By making these adaptations, my method provides little, if any, chance of obtaining inaccurate results if I carry out the investigation properly. I am using technical equipment for precise measurements that measure to two decimal places for reliability.
Final investigation
This is how I plan to set up my experiment.
Method:
1) Cut 7 samples of the same type of potato to 1cm³ on the white tile using the ruler and blade.
2) Blot each potato cutting in the same way so that all excess water is removed.
3) Weigh each potato cutting and record using the scales.
4) Measure 10 ml of 7 different concentrations of sucrose solution into 7 different medium sized test tubes using measuring cylinder. These concentrations must be 0.0M [distilled water], 0.2M [2 parts sucrose, 8 parts water], 0.3M [3 parts sucrose, 7 parts water], 0.4M [4 parts sucrose, 6 parts water], 0.5M [half sucrose, half water], 0.7M [7 parts sucrose, 3 parts water] and 1.0M [all sucrose].
5) Place each potato cutting in separate concentrations using the tweezers and leave to stand for 20 minutes. [Time accurately using stopwatch]. Hold test tubes in test tube rack.
6) Remove each potato cutting from sucrose solutions and weigh using measuring scales.
7) Repeat steps 1 – 6 but leaving experiments to stand for 48 hours instead of 20 minutes.
8) When all initial and final masses have been collected, calculate difference in grams, and then percentage difference [using formula that has previously been given].
9) Compile individual results with class results to calculate a class average.
10) Plot class averages for each period of time onto a graph.
I feel that my method is good because I will accurately be measuring only one variable, and maintaining a consistent and fair test, with controlled factors. I am also going to use equipment, and collect data to a suitable and appropriate complexity, so that I can obtain highly precise results and an educated conclusion.
Collecting the results
20 MINUTE RESULTS
Concentration/M Initial mass/g Final mass/g Mass difference/g Percentage
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