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Determine the solute concentration of potato tissue

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Introduction

Preliminary Experiment Aim The aim of this experiment is to determine the solute concentration of potato tissue; i.e. To investigate at which point the sucrose concentration is the same as the solute concentration inside the potato (an equilibrium is reached) Introduction Osmosis is the movement of water molecules from an area of high concentration; (a weak solution), to an area of low concentration; (a strong solution), through a partially permeable membrane. My experiment will prove that the concentration inside the potato is lower than the concentration of the water molecules, outside the potato if using distilled water or very low concentrations of sucrose solution. Preliminary Method Cut two potato cylinders to the correct sizes e.g. 5cm in length, and dry them out using paper towels. It is important to dry out the potato cylinders because the excess water inside would have an effect on the results, and this would therefore create an unfair experiment. Then one must record their masses and lengths. Place them into the two different solutions; 1.0M of sucrose solution and distilled water, and leave them for fifteen minutes. One must leave the potato cylinders in the two different solutions for at least fifteen minutes because this is a minimum time, in which the starch particles will be able to diffuse into the surrounding liquid, if indeed that is the outcome. ...read more.

Middle

potato cylinder would increase in mass but the potato cylinder that was placed in 30 cm cubed of 1.0M of sucrose solution would be the only one to decrease in mass. The sucrose molecules in the sucrose solution are too big to be able to diffuse through the potatoes permeable membrane. In my main experiment I can predict that with a lower concentration of sucrose solution there will be a bigger increase in mass size. Results Mass: Sucrose (moles) Mass Before (grams) Mass After (grams) Mass change (grams) 0.0 2.663 2.801 0.138 0.1 2.914 2.760 -0.154 0.2 2.668 2.740 0.072 0.3 2.681 2.610 -0.071 0.4 2.854 2.753 -0.101 0.5 2.880 2.810 -0.070 0.6 3.035 2.823 -0.212 0.7 2.691 2.563 -0.128 1.0 2.843 2.723 0.138 Length: Sucrose (moles) Length Before (cm) Length After (cm) Length change (cm) 0.0 5.6 5.8 0.2 increase 0.1 5.6 5.7 0.1% increase 0.2 4.3 5.5 1.2% increase 0.3 4.7 4.3 0.4% decrease 0.4 4.4 4.5 0.1% increase 0.5 4.4 4.6 0.2% increase 0.6 4.5 4.7 0.2% increase 0.7 4.6 4.3 0.3% decrease 1.0 4.6 4.5 0.1% decrease Width: Sucrose (moles) Width Before (cm) Width After (cm) Width change (cm) 0.0 0.6 0.6 0 0.1 0.8 0.7 0.1% decrease 0.2 0.7 0.6 0.1% decrease 0.3 0.6 0.7 0.1% increase 0.4 0.8 0.7 0.1% decrease 0.5 0.8 0.6 0.2% decrease 0.6 0.7 0.7 0 0.7 0.8 0.8 0 1.0 0.8 0.7 0.1% decrease Percentage Changes in potato mass: 0.0M 6.29 ...read more.

Conclusion

However I only had one anomaly in my experiment and my conclusions drawn from my experiment were correct, meaning that my actions carried out during the experiment must have been done accurately and carefully. I trust my results because I know that I carried out the experiment by following all of the correct steps, and not just recording my results, but also developing my answers by thinking how and why I ended up with those answers. One method I could review would be when the potato cylinders were dried on the paper towel before they were placed into the solutions, because one cylinder may have been dried for longer which could have created a lower mass, which could have affected my overall results. Also cutting the potato cylinders to the correct lengths, widths and masses and having to measure them with a ruler, was very time consuming and not as precise as I would have liked. Therefore in the future I could use a more scientific way of carrying out this part of the experiment. If I ever carry out this experiment again, I will use a scientific piece of apparatus to record the temperature of the different solutions so that it is fair. Also some parts of the experiment were a bit limiting. For instance, I would have liked to have carried out the experiment a few more times using various types of potatoes, to see if the type of potato makes a difference to the conclusions which can be drawn from the experiment. ...read more.

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