What exactly causes osmotic pressure?


by sameeralord
Tags: osmotic, pressure
sameeralord
sameeralord is offline
#1
Jan29-14, 05:36 AM
P: 635
Hello everyone,

If there is a semi permeable membrane that allows only water to pass through. Also this membrane separates the sides into A and B.

There are big molecules like colloids in side A along with water. Side B has only water . What mechanism causes side A to have more osmotic pressure, and thus allow water to flow from side B to A.

1) Is it because the particles are so big , that they physically reduce the interactions of water molecules in side A with the semi permeable membrane.

2) Is it because the colloid create a chemical interaction with water molecules and prevent them from moving away.

I just want to know if this osmotic pressure created by a pure physical block (like big guy covering small guy) or an actual chemical interaction (Eg big guy holding the small guy)

3) Is osmotic and oncotic pressure mean same thing.

Thanks a lot
Phys.Org News Partner Chemistry news on Phys.org
Space-tested fluid flow concept advances infectious disease diagnoses
New, more versatile version of Geckskin: Gecko-like adhesives now useful for real world surfaces
Researcher develops novel wastewater treatment fabric
Adithyan
Adithyan is offline
#2
Jan30-14, 07:23 AM
P: 52
Quote Quote by sameeralord View Post
Hello everyone,

If there is a semi permeable membrane that allows only water to pass through. Also this membrane separates the sides into A and B.

There are big molecules like colloids in side A along with water. Side B has only water . What mechanism causes side A to have more osmotic pressure, and thus allow water to flow from side B to A.
First of all, osmotic pressure is not the pressure applied by the liquid on one side on the semipermeable membrane. Rather, it is the pressure required to stop the process of osmosis applied against the side having more dilute conditions.

So there is nothing like one of the sides is having higher osmotic pressure or something.

Now for clearer understanding of osmotic pressure, visit this link: http://h2g2.com/edited_entry/A686766


Register to reply

Related Discussions
Osmotic Pressure Biology, Chemistry & Other Homework 1
osmotic pressure General Physics 6
Osmosis, osmotic pressure, vapour pressure... Classical Physics 5
Vapour pressure of solution from osmotic pressure Biology, Chemistry & Other Homework 0
Osmotic Pressure = Osmotic Power Chemistry 1