What is molarity?
Molarity (M) is the most common unit of concentration in chemistry. It measures the number of moles of solute per liter of solution:
M = n / V
Where M = molarity (mol/L), n = moles of solute, V = volume of solution (L).
Molarity vs. molality
Molarity uses volume of solution (mol/L). Molality uses mass of solvent (mol/kg). Molality is temperature-independent because mass doesn't change with temperature, while volume (and therefore molarity) does.