Molality and Molarity

[theMaharajah]

What's the difference between these two? Other than the equations, when do you know when to use Molality and when to use Molarity?

[Darkblade48]

Molarity, as you know, is moles / litre

Molality is mass of solute / mass of solvent

 

You use molality in calculations such as osmotic pressure, boiling point elevation, and freezing point depression.

[Shwarzchild]

Molarity is how concentrated a substance is. It's moles of solute over Liters of solution. A solution is a homogeneous mixture of two or more substances in a single phase, and solute is the dissolving medium in a solution.