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Determine the concentration of sucrose in potatoes using the principle of osmosis.

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Introduction

Thursday 21st September 2006. Determine the concentration of sucrose in potatoes using the principle of osmosis. By Rose Bickerstaff. Aim. The aim of this experiment is to find the concentration of sucrose in the potato. Prediction/hypothesis. Osmosis is defined as the diffusion of water molecules from a high concentration to a low concentration through a semi-permeable membrane. From my preliminary trials, I believe that my graph will have roughly the same trend as the one from my preliminary results; they will just be more accurate. I think that when I do my actual experiment and I use different concentrations of the solution; I think that the results will still follow the trend of the graph. The molecules will continue to diffuse until the area in which the molecules are found reaches a state of equilibrium, meaning that the molecules are randomly distributed throughout an object, with no area having a higher or lower concentration than any other. When there is a high concentration of water, it is also called 'high water potential.' ...read more.

Middle

Sucrose Water 30 0 20 10 15 15 10 20 0 30 I am going to change the concentration of the sucrose solution between 0 and 1 molar and will measure the change in weight after osmosis has occurred, because I have done a preliminary experiment, by looking at these results I can now determine roughly what my results will be for the actual experiment. From my preliminary results, I have determined that I will use the same time length as before (20 minutes) and from this I have decided that I will use the following concentrations of the sucrose solution: By using osmosis of different molecular values of sucrose solution, I will be able to measure the difference in weight before and after osmosis, and thus workout how much water has moved from the high concentration to the low concentration through the semi-permeable membrane (the potato). To make the solutions, I will have to add different amounts of distilled water to make the solution stronger/weaker, and I will measure it by using a measuring cylinder for the different amounts of water and sucrose. ...read more.

Conclusion

From my graph you can see that the two lines have the same trend. This reinforces the fact that there are no anomalies. It also indicates that my hypothesis was correct; I expect that the lower the concentration of the sugar solution in the test tube the larger the mass of the potato will be. As the shape of my graph is irregular I cannot work out a formula. Evaluation. It was easy to control the variables for this experiment. Also the equipment was very accurate and was therefore very easy to make the measurements. My results were very reliable and the repeat readings were extremely close together. All of my results fit the pattern, which is extremely good as it shows me that all of my results were accurate. If I were to repeat the experiment, I would carry out more tests to ensure that my tests were completely fair. I think that my results were really reliable and accurate, as I measured everything with great care and I also repeated each experiment more than once so that a fair test was ensured. ...read more.

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