Does the concentration of a solution affect osmosis? -- A* - page 1
Keywords: Biology Osmosis Concentration Sucrose solution
By georgie1 on 31/12/2009
Level: GCSE Key Stage 4 (Years 10-11)
Page Number: 1 of 10 pages: 1 2 3 4 5 6 7 8 9 10
Does the concentration of a solution affect the osmosis across the membrane of a potato cutting?
Investigation to find out how the osmosis of a potato cutting is affected when left to stand in different concentrations of sucrose solution, for different periods of time (20 mins and 48 hrs)
The aim of my investigation is to discover what factors affect the osmosis of a potato cutting when left to stand in sucrose solution. Therefore, I will need to record the change in mass of the potato cutting by recording the mass before and after the experiment. To work out the percentage difference, I will need to use the following formula:
Percentage Difference % = Difference in mass g x 100
Original mass g
Osmosis is the diffusion of water molecules from a lower concentration of solution, to a higher concentration of solution, through a partially permeable membrane. In this case, when the potato cutting is placed in a sucrose solution, the water molecules will pass through the partially permeable membrane of the potato, to the other side of the potato cutting, depending on which side is more concentrated with water.
The input (independent) variable of this experiment is the concentration of the sucrose solution, because this is the factor that needs to be changed in order to see how it varies the rate of osmosis. I have chosen to use concentrations of 0.0M, 0.2M, 0.3M, 0.4M, 0.5M, 0.7M and 1.0M, so that I have a wide range of results. I will easily be able to depict a definite and more precise conclusion when comparing my results. The output (dependent) variable that I will be measuring in this experiment is the percentage difference in mass of the potato cuttings. If mass is gained, water will have been transferred into the potato cutting by osmosis, and vice versa. The factors of this experiment that I am going to control are:
• Temperature of the solutions. If the temperature of the laboratory is too high, too low, or inconsistent, then the rate of osmosis will be affected slightly. If the temperature is lower than it should be, then the mobility of the water molecules will decrease, which will cause the rate of osmosis to decrease. In the same way, if the temperature is too hot, then the mobility of water molecules will increase and cause the rate of osmosis to increase. However, if the temperature becomes far too hot, then
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