Investigating Osmosis

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Investigating Osmosis

Introduction:

Over the past term we have been studying osmosis and diffusion. It is

when you put a strong solution into a weaker solution such as sugar.

Osmosis is described as the passage of water from a region of high

water concentration through a semi-permeable membrane to a region of

low water concentration. If the solutions on each side are equally

concentrated then there will be no movement of water across the

membrane. If the solution outside the cell has a low concentration,

the cells become affected because water is flowing into them, if the

solution outside the cell is of high concentration the water flows

out. If two solutions of different concentration are separated by a

semi-permeable membrane which is permeable to the smaller solvent

molecules but not to the larger solute molecules, then the solvent

will tend to diffuse across the membrane from the less concentrated to

the more concentrated solution. This process is called osmosis. Pure

water has a molecular weight of 18 grams/mole, so its concentration is

approximately 55 Molar. Osmosis is why drinking salty water could

damage your body. When you put salt water in your stomach, osmotic

pressure begins drawing water out of your body to try to dilute the

salt in your stomach. This could cause you to dehydrate.

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Definition of osmosis:

Osmosis is the passage of water from a region of high water

concentration through a semi-permeable membrane to a region of low

water concentration.

Aim:

To see how concentration affects osmosis on a potato.

Prediction:

I predict that the higher the concentration of molar solution, the

more the potato chip will weigh.

Plan:

A potato will be cut using a cork borer and knife to equal lengths;

this will keep the surface area equal. Then the starting mass will be

measured. To each test tube a cut piece of potato will be added and

its mass labeled on paper. These will be left for 5 minutes.

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