The Effect of Osmosis on Potato Tissue When Placed In Different Concentrations of Sugar Solutions - Essay Example

of the ; The Effect of Osmosis on Potato Tissue When Placed In Different Concentrations of Sugar Solutions.Definition of Osmosis. Osmosis is the spontaneous passage or diffusion of water or other solvents through a semi -permeable membrane (i.e. a membrane that blocks the passage of dissolved substances or solutes).The solvent molecules pass from a region of their higher concentration to a region of their lower concentration through the semi permeable membrane. (Encyclopaedia Britannica :2005 Deluxe Edition .CD-ROM).Pilot Experiment.

Place 4 potato slices -each a quarter of an inch in thickness - in 4 water bowls in which 1,2,3 and 4 spoons of sugar have been dissolved respectively. After leaving the bowls undisturbed for a day we notice that the potato slices in the bowls are shrunken and that the potato slice in the beaker containing water with 4 teaspoons of sugar dissolved in it has shrunk the most. This is in contrast to the potato slice in the first beaker in which only 1 teaspoon of sugar was dissolved and which has shrunk the least.

This pilot experiment will now be conducted in a much more accurate fashion and the investigation will deal with sugar in moles per litre of solution and the weight difference of the potato slices will be determined in order to correlate the sugar solution molarity with the change in weight of the potato slice. Main Experiment.Aim- The purpose of this experiment is to determine the effect of osmosis on potato tissue when placed in different concentrations of sugar solutions- 0M, 0.1M, 0.2M, 0.3M.Hypothesis- Place potato tissues of the same dimensions and weight and taken from the same potato in sugar solutions of different molarities (a measure of concentration i.e. the number of moles of sugar present in 1 liter of solution), all at the same temperature and pressure, then osmosis takes place and there will be a difference in the weights of potato slices in the different samples.

Materials needed to conduct the experiment- a sharp knife, a weighing balance, 4 beakers, 4 potato slices, sugar solutions of different concentrations of sugar-0.1M, 0.2M, 0.3M and water with no sugar dissolved in it.Factors taken into account- All the samples were kept at the same room temperature (around 68F/20C) and pressure. The type of solute is the same, so is the type of tissue, weight of the tissue, surface area of the tissue and the rate of evaporation of the solute. Only the concentration of solutions in which the potato slices are immersed is different.

Procedure- Make four similar slices of potato such that each potato slice is around 5gms and is of the same dimensions with the knife. Take the different solutions in different beakers and label the beakers according to the molarity of the solutions taken in them. Put a potato slice in each of the beakers. Leave the beakers undisturbed for at least a day. Then observe the samples and weigh each of the potato slices using the weighing balance.Observations - The following table summarizes the results obtained.

Label on beaker0M(No sugar)0.1M0.2M0.3MAppearance of potato slice The potato appears turgid, swollen and firmThe potato appears shrunken, soft and flabbyThe potato appears more shrunken, soft and flabbyThe potato appears most shrunken, soft and flabbyWeight of potato slices (approximately)5.1gms4.92gms4.76gms4.61gmsChange in Weight of potato tissue+0.1gms-0.08gms-0.24gms-0.39gmsThese observations are depicted by the graph shown below with the concentrations of solutions in which the slices were placed on the x-axis and change in weight of potato tissue on the y-axis.

Conclusions- We observe that this graph is a straight line, and the mass of the potato slice is inversely proportional to the concentration of the sugar solution. This shows that there is a gain or loss in the weight of solution corresponding to the change of water concentration of the cell sap in the potato cells and solution and that Osmosis has taken place in all the samples. In the 0M sample the concentration of water was more in the solution than the cell sap of the potato cells in the tissue, as pure water has the highest water concentration whereas the cell sap contains some sugars and salts.

Hence water entered the potato tissue from the solution through the semi permeable membrane and led to turgidity of the slice and increase in its weight. In the 0.1M sample the concentration of water in the solution was less than that in cell sap of potato tissue, so water moved out into the solution and the slice lost weight by 0.08gms. In the 0.2M sample the difference in concentration of water in solution and cell sap of potato slice was greater than the 0.1M sample. So more water traveled across the semi permeable membrane from cell sap to the solution and made the slice lose weight by 0.24gms. In the case of the 0.

3M solution this weight loss was greatest of all the samples and was observed to be 0.39gms. So we can conclude that the amount of water traveling across the semi-permeable membrane through osmosis in potato tissue is proportional to the difference in concentration of water in the solution and the cell-sap.Safety precautions-This experiment is generally safe but care should be taken while slicing the potato with the knife and adult supervision is necessary while cutting the potato.Works Cited1.) Osmosis. "Encyclopaedia Britannica 2005 Deluxe Edition .CD-ROM."