Isotonic 2 questions

[mps287]

What percent solution is necessary to give an isotonic intravenous infusion of CaCl2?


I know isotonic is equal concentration inside and outside the cell.

If the osmolarity of a red blood cell is 0.3 Osm what percent glucose solution would be isotonic to this cell?

[priyajoshi]

5% glucose = 5grams/100mls = 50grams/liter
Molar mass of glucose = 180.16 grams/mole
Therefore 50grams/liter = 0.278 M or 278 milli osmolar with respect to tonicity, since it does not dissociate.

Answer should be near 5%.
Start with 0.3 Osm in your problem = 0.3 M and work backwards.

[JackBean]

Actually 5% (w/w) Glc is 5 g Glc per 95 g H2O

[priyajoshi]

@Jackbean
Can I ask for a quick explanation of why 5% glucose is 5g per 95 g H20?

I was thinking that hydration would come into play, but the MW of glucose monohydrate is 198.17 g/mole...

[JackBean]

x% solution is x g/100 g solution and solution is made of x g of solute and 100-x g solvent

[priyajoshi]

wow. feelin' kinda dumb about that one....Not only cuz I missed it the first time, but that I had to ask why when it was pointed out.