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Osmosis and Diffusion

Ämne: Biologi, Engelska
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Hypothesis experiment 2: I predict that when we have left the shell-less eggs for 24 houres in distilled water and concentrated sodium chloride the egg in the water will stay the same but the egg in the sodium chloride will dissolve.Hypothesis experiment 4: I predict that the strip in the suguar solution will be dryed out but the strip in the water will stay the same.

Hypothesis diffusion experiment: I predict that the water will become purple, equally purple over the whole Petri dish.

Hypothesis Osmosis experiment: I predict that the cups with suguar in the will become dry and that the cup with nothing in will stay wet. I also predict that the suguar in the cups will go away and water will take it’s place.

Results experiment 2: The egg in the water sunk but the egg in the NaCl floated on the surface.

Results experiment 4: The strip in the water became bigger and got a greater mass. However the strip in the NaCl became smaller and got a lighter mass.

Results diffusion experiment: The crystal dissolved in the petri dish and the water in it became colored purple by the crystal atoms.

From these experiments we can conclude several things. However we can cocnlude different things from the diffusion and the osmosis experiments.


In the potatoe with suguar there was a high concentration in the boal, the water in the potatoe wanted to even out so it went out to the boal. There is a semi-permeable membrane, so the water can enter the to the suguar, but the suguar molecules are too large to enter the potatoe. So the water evens out the consentration

Osmosis is a one way diffusion. This we can see from the potatoe experiment. Osmosis can also cause pressure. If an object gets filles up to much then it can explode.


Diffusion is energy or matter from a higher concentration to a lower concentration, resulting in an even distribution. If a lump of sugar is placed in the bottom of a cup of water, the sugar will dissolve and slowly diffuse through the water, but if the water is not stirred it may be weeks before the solution approaches homogeneity.
All types of diffusion follow the same laws. The rate of diffusion is proportional to a specific property of the substance, which in the case of heat or electricity is called conductivity; in the case of matter, this property is called diffusivity or the diffusion coefficient.
As distinct from stirring, which is a process of mixing masses of material, diffusion is a molecular process, depending solely on the random motions of individual molecules. The rate of diffusion of matter is therefore directly proportional to the average velocity of the molecules
If one molecule is four times as heavy as another, it will, in the case of gases, move half as fast and its rate of diffusion will be half as great. Advantage can be taken of this difference to separate substances of different molecular weights, and in particular to separate different isotopes of the same substance. If a gas containing two isotopes is forced through a fine porous barrier, the lighter isotopes, which have a higher average speed, will pass through the barrier faster than the heavier ones. The gas is diffused through a series of such barriers for large-scale separation. This technique, known as the gaseous-diffusion process, is widely used in the separation of the fissionable uranium isotope U-235 from the non-fissionable U-238


Diffusion processes are of great biological importance. For example, digestion is essentially a process of chemically changing food so that it will be able to pass, by diffusion, through the intestinal wall into the bloodstream. Shock, a condition that frequently follows surgery or injury, is a state in which the blood fluids have diffused excessively through the blood-vessel walls into the body tissues. Treatment of shock consists of injecting chemicals, usually in the form of blood, plasma, or plasma expanders, into the remaining blood fluid to compensate for the loss by diffusion and to alter pressure in the blood vessels, thus obviating further loss (see Blood Transfusion; Circulatory System).

When we drink a glass of suguar water we get the same amount of suguar in every sip we take. This is because the suguar has defused in the water.

When we put perfume on we want to smell good. If we put perfume on our neck then people can smell the smell all over. This is because of diffusion. The molecules move from high concentration (body) to low concentration (air). When we then smell the smell we actually get perfume molecules in our nose.

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