I'm curious about this question.
- If I put red blood cell in a solution of NaCl, and water moves in RBC and hemolyses.
Does water move because of molarity difference or osmolarity between the RBC and surrounding solution? I thought molarity causes the movement of water because water potential is affected by the conc. of dissolved particles of solute.
-Does diffusion rate of non-electrolyte (eg. glucose) depend on size of solute particle or solubility in lipids? I thought it was solubility in lipids. Because glucose is a big solute. If it's big, then it can't go through the membrane. Also, if the partition coefficient was low, then its diffusion rate is fast.
Thank you

You appear to be asking primarily about liquids and properties of molecular movement. Here is a website that discusses Fluid Concepts.

From Masterton and Slowinski Chemical principals
pi (osmotic pressure)=MRT. If your salt solution has a lower concentration of salt than your RBC...the water solvent will strive to pass through the membrane to establish equilibrium and cause hemolysis. When the vapor pressure of your solution equals that of the RBC you have an isotonic soltution.
You can also have more salt...and shrink the
RBCs.
The vapor pressure is the driving force.

for the rate question.. yes.. Both size and solubility have effects. A small fat soluble molecule can pass easily where as a large polar molecule will also not be soluble in the lipid and physically dificult to pass through the membrane.

Note that cells have special structures that open a passage way to allow specific molecules in our out vs an inert semipermible membrane.
Active pumps vs passive process

hope this helps