– What is osmolality?

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I got a requisition for serum and urine osmolality. I’ve done some searching, but I still don’t understand what those mean. Help?

In: Biology

5 Answers

Anonymous 0 Comments

Osmolality, as you might guess, is related to the concept of *osmolarity* and, by extension, osmosis and molarity.

Molarity and osmolarity are similar, but *os*molarity brings in the concept of osmotic pressure by accounting for things that dissociate in solution. Salt, for example, dissolves into Na^+ and Cl^- ions, and so when you consider a solution of salt, its *osmolarity* is higher than its *molarity.*

With me so far? Good. Here’s how osmola***r***ity and osmola***l***ity differ: Osmolarity is defined per unit *volume of solution,* while osmolality is defined per unit ***mass of solvent.***

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