Molality

[camerons19]

Molality, which is defined as mol/kg solution, would be the same as molarity in water, correct? Since 1L water weighs 1 kg?

[admin]

Here is the easy answer: for the MCAT, YES.

You don't have to read more if you don't want to!

To be precise, molality is the number of moles of solute per kilogram of solvent. Because the density of water at 25 oC (which is standard temp for liquids) is about 1 kg per liter, molality is approximately equal to molarity for dilute aqueous solutions at this temperature. This is a useful approximation, but remember that it is only an approximation and doesn't apply when the solution is at a different temperature, isn't dilute, or uses a solvent other than water.