Osmosis

[Primarygun]

Why water flow from high concentrated solution to low?

Isn't the pressure of the mixture of sodium chloride+water exerts a higher pressure to the lower?

Hence, the salt+water would flow to the low one.

But, in fact, the truth contradicts this. Why?

I hope I can find out the answer

[Skye]

Water molecules move both ways as they jiggle about. But there are more water molecules on one side than the other, so more will flow from this side to the other until both sides even out.

[swansont]

The concentration evening out is due to diffusion. (Fick's law) Osmosis will occur with an appropriate semi-permeable barrier in place.

 

Osmosis is a reversible process, but diffusion is not.

[Primarygun]

What about if X(a substance)+water mixture have a higher pressure than pure water on the other side? Is the process reversible?

[Skye]

Yeah, you can pump water through a semi-permeable membrane to purify it. There was a thread on it a while ago.

[Primarygun]

I can't find the post.

Would you simply tell me the answer?

The pressure of mixture is higher than the pressure of water for a general osmosis.

[pulkit]

The process is called reverse osmosis. It is used amongst other things to purify sea water and make it fit for drinking.

[aommaster]

Is this similar to active uptake in plants, only with water?

[Primarygun]

And, which substance mixs with water to generate a higher pressure than pure water itself?