what is the relationship of donnan effect to :?

Question

a. osmotic pressure
b. pH
c. capillary walls

please guys. i need it tomorrow. thanks

Answer 1

Probably too late by now, but if you're still wondering...

The Donnan Effect (which is usually referred to as the Gibbs-Donnan Effect) has to do with charge affecting ion flow through a permeable membrane. Cells make use of this effect to perform a lot of different tasks, most notably the production of ATP, the molecule most of your body uses for energy.

So, for example, if you have a lot of H+ on one side of a membrane, then it will be harder for Na+ to come from the other side, even if there's a concentration of Na+ on the other side to drive it. pH, being a measure of H+ concentration, thus can have a lot to do with this effect (though not always - sometimes it's other ions that are involved).

A different but related effect causes water to be drawn to the side of a membrane with lots of solute. So you can see how this effect might change osmotic pressure: A charge accumulation on one side could reduce the total amount of solute on one side, and thereby the osmotic pressure.

Hope that helps!