Osmolality vs. Osmolarity

[bunneh]

What is the difference between osmolality and osmolarity?

[tlc2u]

what is the difference between osmolality and osmolarity?

the words can be used interchangeably. however they do mean sligthly different things.

example for the osmolality and osmolarity of the blood.

osmolality is the weight of the plasma without the weight of the solutes.

osmolarity is the volume of the plasma including the volume of the solutes.

the solutes in the blood are the electrolytes.

mosby's dictionary 6th edition says:

osmolality is the osmotic pressure of a solution expressed in osmoles (or amount of moles or molecules or particles in a solution) per kilogram of water. kilogram =weight

osmolarity is the osmotic pressure of a solution expressed in osmoles per liter of the solution. liter= volume

osmolality is similar to tonicity, like hypotonic, isotonic, or hypertonic iv solutions. if the iv fluid has a low amount of salt molecules as in 0.45%ns then it is hypotonic and through osmotic pressure water will flow out of the blood vessels to get the amount of salt molecules per kilogram of water back to homeostasis or bring it back to 0.9%.

if the iv fluid has a higher concentration of salt as in 3%-5% ns then it is hypertonic. when you give a hypertonic iv fluid into the blood vessels and they have too much salt then water will be drawn into the blood vessels through osmosis or osmotic pressure to dilute the salt back to homeostasis or 0.9% sodium.

osmolality is the osmotic pressure of the fluid, where tonicity is the amount of particals in the fluid that determines the osmotic pressure.

[bunneh]

That helped a lot, thank you!