Final answer:
The molality of a solution is calculated as the number of moles of solute divided by the kilograms of solvent, and is denoted by 'm'. To find the molality using freezing point depression, you first find the moles of solute and then divide by the kilograms of solvent. Molality is crucial for determining the molar mass of unknown solutes using physical properties.
Step-by-step explanation:
Understanding Molality
Molality, often denoted by the letter m, is a measure of concentration used in chemistry that relates the moles of solute in a solution to the mass of the solvent in kilograms. To calculate the molality of a solution, you need to divide the number of moles of solute by the mass of the solvent in kilograms. For instance, if the number of moles of ions in a solution is known, and the mass of the solvent is given, you can determine the molality of the ions in the solution. You can also determine the molality by using the freezing point depression value (ΔTƒ), given that the effect on the freezing point is proportional to the molality of the solution.
When the molality is calculated as 1.2 m, this represents a ratio of 1.2 moles of solute to 1 kg of solvent. Furthermore, knowing the molality can help you to calculate the molar mass of an unknown solute by dividing the grams of the solute by the moles. This is vital in identifying the unknown compound, which is relevant when physical properties such as freezing point depression or boiling point elevation are involved.