The advantage of molarity is that it is generally easier to measure the volume of
a solution, using precisely calibrated volumetric fl asks, than to weigh the solvent, as
we saw in Section 4.5. For this reason, molarity is often preferred over molality.
On the other hand, molality is independent of temperature, because the concentration is
expressed in number of moles of solute and mass of solvent. The volume of a solution typically increases with increasing temperature, so that a solution that is 1.0 M at 25°C may become 0.97 M at 45°C because of the increase in volume on warming.