## Isotonic 2 questions

For discussing the functions of different structures of all organisms.

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### Isotonic 2 questions

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?
mps287
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Posts: 2
Joined: Mon Dec 07, 2009 8:53 pm

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.

priyajoshi
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Posts: 19
Joined: Mon Oct 19, 2009 7:21 pm

Actually 5% (w/w) Glc is 5 g Glc per 95 g H2O
http://www.biolib.cz/en/main/

Cis or trans? That's what matters.

JackBean
Inland Taipan

Posts: 5333
Joined: Mon Sep 14, 2009 7:12 pm

@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...
priyajoshi
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Posts: 19
Joined: Mon Oct 19, 2009 7:21 pm

x% solution is x g/100 g solution and solution is made of x g of solute and 100-x g solvent
http://www.biolib.cz/en/main/

Cis or trans? That's what matters.

JackBean
Inland Taipan

Posts: 5333
Joined: Mon Sep 14, 2009 7:12 pm

### Re: Isotonic 2 questions

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.
priyajoshi
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Posts: 19
Joined: Mon Oct 19, 2009 7:21 pm