Assuming complete dissociation, what is the molality of an aqueous solution of KBr whose freezing point is -2.95 °C? The molal freezing-point-depression constant of water is given in Table 13.4.

Freezing point depression is a colligative property that describes the lowering of a solvent's freezing point when a solute is added. The extent of this depression is directly proportional to the molality of the solution and the freezing-point-depression constant (Kf) of the solvent. For water, Kf is typically 1.86 °C kg/mol, meaning that for each mole of solute per kilogram of solvent, the freezing point decreases by this amount.

Molality (m) is a measure of concentration defined as the number of moles of solute per kilogram of solvent. It is particularly useful in colligative property calculations because it directly relates to the effect of solute on the properties of the solvent. Unlike molarity, molality is not affected by temperature changes, making it a stable measure for solutions in thermal calculations.

Ionic compounds, such as KBr, dissociate into their constituent ions when dissolved in water. For KBr, it dissociates into K⁺ and Br⁻ ions. This dissociation increases the number of particles in solution, which is crucial for calculating colligative properties like freezing point depression, as the effect is based on the total concentration of solute particles rather than just the number of solute molecules.