Investigating the effects of different sugar concentrations on Osmosis.

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Qais Hammad

Investigating the effects of different sugar concentrations on Osmosis

Introduction

Osmosis is the net movement of water molecules through a semi-permeable membrane from a less concentrated solution to a more concentrated solution.  A semi-permeable membrane allows only water molecules and small solute molecules to pass through the pores in its membrane.  Osmosis continues until the water molecules are distributed evenly on both sides of the membrane.  

The aim of the experiment is to investigate the effects of different sugar concentrations on osmosis.  To carry this investigation out, the osmosis in potato chips placed in different sugar concentrations will be measured.  This will be carried out by measuring the masses of the chips before and after the experiment and from them discovering the percentage changes in mass.  In 6 petri dishes, each containing exactly 50ml of their specific concentration of sugar, 3 chips are placed (this is a quicker method of doing repeats).  Once the chips are all in their petri dishes, they are left for 4 hours at room temperature.  After these four hours, the new masses of the chips are measured and from the results the percentage change in mass is discovered.

I predict that the chips will increase in mass for the experiments with low concentrations, as water will osmose from the solutions into the chips, because the concentration will be higher in the chip.  The mass will increase, as will the volume, because when the water osmoses into the cells of the potato chips, the cells become turgid (as there is more water in the them) and the potato chips will increase in both size and mass.  Then, in the experiments with higher concentrations, the chips will decrease in mass, as water will have osmosed from the chips into the solutions, due to the fact that the concentration will be higher in the solutions.  The cells of the potato chips will become flaccid, as they will have lost water through osmosis to the salt solution, and consequently the chips will decrease in size and mass.  I predict that in the experiments of lower concentrations, in which water will osmose from the solutions into the chips and their masses will increase, the increase in mass of the chips will get smaller as the concentrations get higher, as less water will have to osmose into the chip in order for the water molecules to be evenly distributed on either side of the membrane.  I think that the chips will decrease more in size as the concentrations get higher, because more water will have to osmose in order for the water molecules to be evenly distributed on either side of the membrane.

Prior to the investigation, a preliminary experiment was carried out.  This is displayed below.

Preliminary Experiment

Aim:   

To investigate the effects of different sugar concentrations on osmosis.

Method: 

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Four different concentrations of sugar solution were tested: 0M (distilled water), 0.3M, 0.6M, and 0.9M.  Four potato chips were cut to 50mm, at an angle so that they could be measured before and after the experiment without mixing them up.  

Four test tubes were used: one for each of the different solutions used.  A chip was placed in each test tube and left for 30 minutes.  After the 30 minutes, the chips were removed from the test tubes and their new lengths and changes in length were recorded.

Results:

Table ...

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