What factors affect osmosis in potato cylinders?

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What factors affect osmosis in potato cylinders?

My aim is to investigate the different factors that effect osmosis in potato cylinders.

Osmosis is the diffusion of water molecules from an area where they are in concentration to an area of a lower concentration through a partially permeable membrane and osmosis will not usually occur when something is fully permeable.

The diagram below is an example of when osmosis takes place:

The possible variables that could effect this investigation are:

  • Temperature- In warm solutions the particles have a higher amount of kinetic energy and therefore move more quickly. This could increase the rate that water molecules diffuse through the partially permeable membrane so the temperature must remain the same.

  • Strength of sugar solution- the more concentrated a solution is the stronger it is which means less water molecules which effects how osmosis occurs.

  • Surface area of potato cylinder- more surface area means that a higher amount of water can be absorbed and more osmosis can take place, the surface area for each potato cylinder must also be the same.

  • Amount of sugar solution- changing the volume of sugar solution could mean that some potato cells would not be in contact with the solution and therefore would decrease the amount of osmosis.

  • Time- if one cylinder was left to perform osmosis for 24 hours and another for only

 2 hours, this would be an unfair test so all cylinders must be measured for the same length of time to succeed in making it a fairer test.

I have chosen to investigate how the strength of the sugar solution affects osmosis in potato cylinders. For this investigation the input variable will be the strength of sugar solution, the dependant variable will be the weight change because water molecules will either be lost or gained through osmosis.  The temperature, surface of potato cylinder, amount of sugar solution and time will be the controlled variables of this experiment to make it a fairer test.

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Before starting the investigation, I carried out preliminary work on the strength of sugar solution and the effect it had on visking tubing. Visking tubing is a partially permeable membrane and it does not let sugar molecules diffuse through it.

The diagram above shows that in boiling tube A the water from the 0.0M solution in the boiling tube diffused into the visking tubing containing sugar solution. This is because there is a higher concentration of water in the boiling tube and a lower concentration of water in the visking tubing. The visking tubing then expanded because it ...

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**** A generally good account of the investigation with a sound understanding of osmosis evident. However, there is too much imprecise use of scientific language.