Chemical potential vs hydro-static pressure during osmosis


by Urmi Roy
Tags: chemical, hydrostatic, osmosis, potential, pressure
Urmi Roy
Urmi Roy is offline
#1
Oct20-13, 08:06 PM
P: 692
So when osmosis between two solutions (separated by a semipermeable membrane),takes place, the solvent travels from the side where its chemical potential is higher to the side where its chemical potential is lower.
However, this results in a difference of levels of fluids across the membrane.

Doesn't this contradict the laws of hydro-statics? Is chemical potential enough of a driving force to overcome hydro-static forces?

Thanks a lot!
Phys.Org News Partner Engineering news on Phys.org
Lifting the brakes on fuel efficiency
PsiKick's batteryless sensors poised for coming 'Internet of things'
Researcher launches successful tech start-up to help the blind
Useful nucleus
Useful nucleus is offline
#2
Oct20-13, 11:07 PM
Useful nucleus's Avatar
P: 240
Can you describe the setup of the system you are interested in? Typically one is interested in systems where the exchange takes place only through the membranes.
Urmi Roy
Urmi Roy is offline
#3
Oct20-13, 11:12 PM
P: 692
Yeah, I'm just considering a system in which a structure that looks like a u-tube manometer, but with a semipermeable membrane at the bottom of the 'U' shape, which separates 2 solutions and supposed the one on the left is more concentrated. The exchange does take place only via the membrane.

DrDu
DrDu is offline
#4
Oct21-13, 03:39 AM
Sci Advisor
P: 3,371

Chemical potential vs hydro-static pressure during osmosis


Yes, the forces are quite large. The chemical potential of the solvent depends on both the concentration of the solute and the pressure. In equilibrium, the chemical potential of the solvent has to be equal on both sides, hence for different concentrations of the solute, pressure has to be different, too.
Urmi Roy
Urmi Roy is offline
#5
Oct21-13, 11:34 AM
P: 692
Quote Quote by DrDu View Post
Yes, the forces are quite large. The chemical potential of the solvent depends on both the concentration of the solute and the pressure. In equilibrium, the chemical potential of the solvent has to be equal on both sides, hence for different concentrations of the solute, pressure has to be different, too.
The hydro-static forces are basically due to the weight of fluid column, so when chemical equilibrium is established, is it like the gravitational potential energy is just balanced by the chemical potential energy?


Register to reply

Related Discussions
chemical potential vs pressure and temperature; difficulty with Fermi gases Classical Physics 21
Time for Hydro System to Reach Static Equilibrium Mechanical Engineering 0
Osmosis, osmotic pressure, vapour pressure... Classical Physics 5
Minimum Pressure applied by reverse osmosis? Biology, Chemistry & Other Homework 1
Question about osmosis and osmotic pressure Biology, Chemistry & Other Homework 3