Is molality or molarity dependent on temperature? Explain your answer. Why is molality, and not molarity, used in the equations describing freezing-point depression and boilingpoint elevation?

Molality (represented by 'm') is defined as the number of moles of solute per kilogram of solvent. On the other hand, molarity (represented by 'M') is defined as the number of moles of solute per liter of the solution. In other words, Molality (m) = moles of solute / mass of solvent (in kg) Molarity (M) = moles of solute / volume of the solution (in L) Now we will analyze which of these is dependent on temperature.

Molality depends only on the mass of the solvent, which typically does not change significantly with temperature. Molarity, however, depends on the volume of the solution, which can change with temperature due to the expansion or contraction of the solvent. Therefore, molarity is the one that depends on temperature, while molality is independent of temperature.

Freezing-point depression and boiling-point elevation are colligative properties, which means they depend only on the quantity of solute particles in the solution and not on the type or nature of the solute particles. The equations for freezing-point depression and boiling-point elevation are given by: ΔTf = Kf * m * i ΔTb = Kb * m * i Here, ΔTf is the freezing-point depression, Kf is the freezing-point depression constant, ΔTb is the boiling-point elevation, Kb is the boiling-point elevation constant, m is the molality of the solution, and i is the van't Hoff factor (number of particles formed by each solute molecule). Molality is used in these equations because it is independent of temperature and accurately reflects the relationship between the solute quantity and the changes in the freezing and boiling points. If molarity were used, the values would change with temperature, leading to incorrect results and possible inaccuracies when predicting the behavior of the solution. In summary, molality is independent of temperature, while molarity depends on temperature. Molality is used in equations describing freezing-point depression and boiling-point elevation because it provides a more accurate and consistent relationship between the solute quantity and the changes in freezing and boiling points.