HELP WITH HOMEWORK! What would happen to Blood cells in the following solutions?

What would happen to red blood cells in the following solutions:

  1. Distilled water,
  2. 0.075M NaCl,
  3. 0.4M NaCl,
  4. 0.28M Urea

And what approximately would their light scatter be?


1 Answer
Apr 6, 2018

See below


I think the ion concentration in red blood cells is about 300mM, or about 300 milliosmolarity. Basically means that of all the dissolved ions in a red blood cell, the concentration of them is about 300 mM, or 0.3M

For the sake of this discussion, water flows from where it is a higher concentration to where it is a lower concentration. Or said the other way, water flows from lower osmolarity to higher osmolarity (since water is higher in concentration in a lower osmolarity solution).

  1. Pure water: the red blood cell will swell and probably burst, since water will flow into it.

  2. The osmolarty of this solution is 0.15M (0.075 + 0.075) - for osmotic pressure, it doens't matter the identity of the solute, just that there is a solute (within reason). So water will flow into the red blood cell....and swell it. maybe burst, maybe not.

  3. 0.4M NaCl is a 0.8M osmolarity solution, and so the water is higher concentration in the red blood cell. This means water will flow OUT of the redblood cell, and it will shrivel, shrink.

  4. 0.28M Urea - urea is not ionic, but it is still dissolved solute. It is less concentrated that the red blood cell, so water will flow into the red blood cell, but only slightly. (assuming 0.3M osmolarity red blood cell).

Again, I'm assuming the red blood cell is 0.3 osmolarity. (0.3M osmolarity)