Detailed Animation on Osmosis
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4 سال پیش
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Osmosis is the diffusion of
Osmosis is the diffusion of water molecules down their concentration gradient, across a semi-permeable membrane.
This membrane is semi-permeable because water molecules can pass through it, but solute molecules cannot move as they are too large.
The beaker below shows a semi-permeable membrane separating a solution with a low solute concentration on the left from a solution with a higher solute concentration on the right.
There is an overall passive movement of water molecules from the solution with a low solute concentration to the solution with a high solute concentration.
This is because the water molecules move to even out any difference in concentration, just like in ordinary diffusion.
This net movement of water molecules will cause the water level to rise on the right and fall on the left.
Hydrostatic pressure is the pressure exerted by a fluid due to the force of gravity acting upon it.
As the column of water on the right gets higher, the hydrostatic pressure it exerts increases.
The hydrostatic pressure acts to push the water molecules back across the membrane, opposing the movement of water by osmosis.
At some point, this pressure is high enough to stop the net movement of water through the membrane by osmosis.
This pressure is known as the osmotic pressure.
The osmotic pressure is determined by the concentration of non-diffusible solutes in the solutions.
If there is a small difference in solute concentration between the two solutions, there is a low osmotic pressure. In this case, a small amount of water crosses the membrane by osmosis, raising the level of the solution on the right slightly.
As a result, the hydrostatic pressure increases slightly, which is enough to prevent any further net movement of water.
However, if there is a large concentration difference between the two solutions, there is a much higher osmotic pressure.
A large amount of water can cross the membrane, raising the level of the solution on the right considerably, before the hydrostatic pressure will be enough to prevent further net movement of water.
This membrane is semi-permeable because water molecules can pass through it, but solute molecules cannot move as they are too large.
The beaker below shows a semi-permeable membrane separating a solution with a low solute concentration on the left from a solution with a higher solute concentration on the right.
There is an overall passive movement of water molecules from the solution with a low solute concentration to the solution with a high solute concentration.
This is because the water molecules move to even out any difference in concentration, just like in ordinary diffusion.
This net movement of water molecules will cause the water level to rise on the right and fall on the left.
Hydrostatic pressure is the pressure exerted by a fluid due to the force of gravity acting upon it.
As the column of water on the right gets higher, the hydrostatic pressure it exerts increases.
The hydrostatic pressure acts to push the water molecules back across the membrane, opposing the movement of water by osmosis.
At some point, this pressure is high enough to stop the net movement of water through the membrane by osmosis.
This pressure is known as the osmotic pressure.
The osmotic pressure is determined by the concentration of non-diffusible solutes in the solutions.
If there is a small difference in solute concentration between the two solutions, there is a low osmotic pressure. In this case, a small amount of water crosses the membrane by osmosis, raising the level of the solution on the right slightly.
As a result, the hydrostatic pressure increases slightly, which is enough to prevent any further net movement of water.
However, if there is a large concentration difference between the two solutions, there is a much higher osmotic pressure.
A large amount of water can cross the membrane, raising the level of the solution on the right considerably, before the hydrostatic pressure will be enough to prevent further net movement of water.
4 سال پیش
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