How does molarity change with temperature?

The molarity of a solution, which is a measure of the concentration of a solute in a solvent, can indeed change with temperature. The change in molarity with temperature is primarily due to the fact that the volume of a solution can change with temperature, affecting the number of moles of solute in a given volume.

The relationship between molarity (M), volume (V), and the number of moles (n) of a solute in a solution is given by the formula:

Molarity (M) = n / V

When the temperature increases, most substances, including liquids and solids, tend to expand and occupy a larger volume. This expansion can cause the volume of the solution to increase, even if the number of moles of solute remains constant. As a result, the molarity of the solution would decrease.

Conversely, if the temperature decreases, substances generally contract and occupy a smaller volume. This contraction can cause the volume of the solution to decrease, leading to an increase in molarity.

It's important to note that the change in molarity with temperature can be more significant for solutions with larger temperature changes and for substances with larger thermal expansion coefficients. Additionally, some solutes might undergo changes in solubility with temperature, which can also affect their concentration in a solution.

To account for the effects of temperature on molarity, particularly in cases where temperature changes are substantial, it's important to consider the temperature dependency of both the solute's solubility and the solvent's volume change. In analytical chemistry, corrections might be applied to accurately represent the concentration of a solution at a specific temperature.