The Effect of Sugar Concentration on the Mass of Potatoes

The Effect of Sugar Concentration on the Mass of Potatoes
This investigation is based upon osmosis. Hence, I am carrying out this experiment to investigate how different concentrations of sucrose (the independent variable) and distilled water solution affect the mass of a potato tuber. apparatus ===== 6 boiling tubes knife -????????? test tube stand sucrose (concentarion OF 0.5 M)- amounts (IN ml): 25, 20, 15, 10, and 5. cork and borer distilled water-same amounts AS electric scales sucrose solution potato measuring cylinder background information This experiment is based upon osmosis and therefore a clear understanding of this is to be obtained. Osmosis can be summed up as, ?the movement of water molecules from a region of higher concentration to a region of lower concentration through a semi-permeable membrane.? Osmosis also depends upon water and solute potential. Ψ-this is the Greek letter ?psi? for water potential. Pure, distilled water has a water potential of zero.
Therefore, solutions containing solutes like sucrose decrease the maximum water potential, making this level below zero, hence negative. prediction Based on this prior knowledge, I predict that the higher the concentration of the sugar solution, the more likely the mass of the potato tuber will decrease. This is because osmosis is the movement of water molecules from where they?re in a higher concentration to a region of lower concentration. Thus being, I believe this will mean that because there is higher water potential in the potato tuber than there is outside, the water molecules will diffuse outside of the tuber into the beaker of solution. This will decrease the mass of the potato as the water molecules leave to an area of higher solute potential until all the particles are evenly spread and equilibrium is achieved. This will mean that the potato cells will become flaccid because water is leaving the cells to an area of lower water potential. This process is called plasmolysis and causes the cell to ?shrink?, which is how the mass should decrease. I also predict that the reverse will occur if there is higher water potential outside the potato tuber. As usual, osmosis will take place but this time water will diffuse from the solution, into the potato tuber. This will mean that the mass of the potato will increase from its original size because water molecules are moving from an area of higher concentration to a lower concentration. This will exert pressure potential in the cell. This will increase the volume of the cell. This pressure potential also increases the water potential until the water potential inside the cell is equal to the water potential outside the cell causing a state of equilibrium. Having a strong cell wall, the plant cells can experience more pressure and will achieve a turgid structure. procedure 1. Using the cork-borer cut 6 potato tubers, each as closely equal in weight as possible, using scales. Record measurements. 2. Place 6 test tubes into a boiling tube stand with the different amounts of distilled water and sucrose soulutions, being: -25ml of 0.5M solution of sucrose -20ml of 0.5M solution of sucrose and 5ml of distilled water -15ml of 0.5M solution of sucrose and 10ml of distilled water -10ml of 0.5M solution of sucrose and 15ml of distilled water. -5ml of 0.5M solution of sucrose and 20ml of distilled water. -25ml of distilled water. 3. Place one of the six potato tubers into each of the boiling tubes. 4. Leave for 24 hours. 5. Re-weigh the tubers. A fair test? In order for this experiment to be accurate, a fair test will be carried out and will include the following: 1. I will use the same concentration of sucrose (o.5M) from the same bottle. This will ensure that all the surcrose solutions are exactly the same concentration 2. I will use distilled water, not tap water. This is because distilled water has a water potential of zero whereas tap water does not. 3. I will measure each solution accurately using a measuring cylinder. 4. I will leave all the potoato tubers in solution for the same amount of time, 24 hours. safety Although this experiment is fairly safe, safety still must be considered. To ensure that nothing is carelessly broken, I will be aware that I am dealing wll delicate glass objects and therefore I will try and be more precautious. If however, glass apparatus or any other apparatus is broken, I will show the teacher and clear up the mess so no one will get injured. I will also have to take into account that there is other people in the class doing the same experiment as I and in that sense I will have to be precautious as well. When using the sucrose solution, I will have to be careful not to spill it. if I do, I must clear it up. I will also put my bags and coat away before I start this experiment to ensure no one will slip and so I can work in a clean environment. results After I had carried out the proceure, I came out with a set of results as following: amounts OF distilled water and 0.5M sucrose present weight OF potato tuber AT the beginning OF the experiment (in grams) weight OF potato tuber AT the end OF the experiment (in grams) 25ml of sucrose with 0ml of distilled water 1.31 0.98 20ml of sucrose with 5ml of distilled water 1.30 1.02 15ml of sucrose with 10ml of distilled water 1.32 1.09 10ml of sucrose with 15ml of distilled water 1.31 1.34 5ml of sucrose with 20ml of distilled water 1.31 1.34 0ml of sucrose with 25ml of distilled water 1.29 1.46 conclusion TO MY results My predictions were correct and my results showed the occurance of osmosis. The higher the concentration of water, the larger the potato tuber as an end result. This showed that the water molecules did diffuse from a region of higher concentration to a region of lower concentration. I also noticed that as the mass of the potato tuber had decreased, the tuber itself was more flaccid than the larger potato tuber. this proved the theory of plasmolysis.

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