• Create Account

# Osmolarity

2 replies to this topic

### #1 samita

samita

Veteran

• Active Members
• 114 posts
2
Neutral

Posted 18 January 2011 - 09:08 AM

This solution

160 NaCl
2.5 KCl
1 CaCl2
2 MgCl2
10 HEPES
10 Glucose

has an osmolarity of about 320, how to calculate it from the molarity of the ionc composition.

### #2 Inmost sun

Inmost sun

Veteran

• Active Members
• 286 posts
59
Excellent

Posted 10 February 2011 - 12:24 PM

I think itīs more in the range of 350 mOsmol...

samita, on 18 January 2011 - 09:08 AM, said:

This solution

160 NaCl
2.5 KCl
1 CaCl2
2 MgCl2
10 HEPES
10 Glucose

has an osmolarity of about 320, how to calculate it from the molarity of the ionc composition.

### #3 bob1

bob1

Thelymitra pulchella

• Global Moderators
• 4,347 posts
224
Excellent

Posted 10 February 2011 - 05:23 PM

Think about it like this... 1 mole of NaCl goes into solution to form one mole of Na+ and one mole of Cl- = 2 Osmole... HEPES and glucose do not do this so the osmolarity is 1 for each mole dissolved.

Assuming your solution above is in millimoles/litre (you should always write solutions with concentration units)
160 mM NaCl = 320 mOsmole
2.5 mM KCl  = 5 mOsmole...   etc I am sure you get the picture.

BTW Inmost sun is correct...