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The aim of this experiment is to find out what affect solutions of different concentrations have on potatoes.

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Investigating the affect of different concentrations of solutions on potatoes Aim The aim of this experiment is to find out what affect solutions of different concentrations have on potatoes. Background Osmosis is a special type of diffusion that involves water moving across a partially permeable membrane. The water will continue to move into an area with a lower water concentration until equilibrium is reached. I have carried out a preliminary experiment by putting 12.5 cm� of water in Visking tubing (a partially permeable membrane) and leaving it in a test tube filled with a strong sugar solution for 40 minutes. I weighed the Visking tubing with the water in on a top pan balance before and after placing it in the test tube. I carried out the same experiment again but filled the Visking tubing with the strong sugar solution and the test tube with water. The results are shown in the table below: Contents of Visking tubing Before (g) After (g) Water 11.1 9.7 Strong sugar solution 13.5 14.6 Prediction I predict that the stronger the solution is that the potatoes are placed in then the less the potatoes will weigh at the end of the experiment. ...read more.


* The freshness of the potato (as fresh as possible)- potatoes as similar as possible will be used in the experiments. * The top pan balance- the same top pan balance will be used to weigh every potato piece before and after the experiment. * The temperature- all the tests will be carried out on the same day. * The amount of the solution in the test tube- there will be 5cm� of salt solution in each test tube. Safety To ensure the experiments are safe a will handle the test tubes carefully and clean up any glass quickly in the case of any breakages. Results 1st Experiment Concentration (Molar) Mass at start (g) Mass at end (g) Change in mass (g) % change in mass 0 0.71 0.70 -0.01 -1.41 0.2 0.75 0.73 -0.02 -2.67 0.4 0.77 0.71 -0.06 -7.79 0.6 0.75 0.68 -0.07 -9.33 0.8 0.80 0.72 -0.08 -10.00 1.0 0.74 0.71 -0.03 -4.05 2nd Experiment Concentration (Molar) Mass at start (g) Mass at end (g) ...read more.


However, the temperature may have changed while the experiments were being carried out and the freshness of the potatoes could have varied. The reliability of the results for most of the concentrations is good with the biggest difference between the two sets of results being 5.02%. However, this excludes the 1.0 Molar concentration that has a difference of 7.79% and this means that its reliability is questionable. Also the result is not situated near the line of best fit on the line graph so this suggests that it is an anomalous result. This is mainly due to the result from the first experiment and this result could have been affected by the potato not being properly dries before it was weighed at the start of the experiment. The experiment could be developed by investigating a larger range of concentrations of the change in mass of the potato or investigating a greater number of concentrations within the same range i.e. 0.1M, 0.2M, 0.3M...1.0M. The experiment could also be extended by investigating the effect of temperature, the amount of the solution or the surface area of the potatoes on the percentage change in mass. Andrew Bottomley Biology Osmosis Coursework ...read more.

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