Is the question formulated correctly for calculating the freezing point and boiling point of each solution, assuming complete dissociation of the solute? For the following: a. 10.5 g FeCl3 in 1.50 * 10^2 g water b. 3.5% KCl by mass (in water) c. 0.150 m MgF2.

Verified step by step guidance

1. insert step 1> Determine the molality (m) of each solution. For FeCl3, calculate the number of moles of FeCl3 using its molar mass, then divide by the mass of water in kilograms. For KCl, use the given mass percentage to find the mass of KCl in 100 g of solution, then calculate molality. For MgF2, the molality is already given as 0.150 m.
2. insert step 2> Calculate the van't Hoff factor (i) for each solute, which represents the number of particles the solute dissociates into. For FeCl3, i = 4 (Fe^3+ and 3 Cl^-). For KCl, i = 2 (K^+ and Cl^-). For MgF2, i = 3 (Mg^2+ and 2 F^-).
3. insert step 3> Use the freezing point depression formula: \( \Delta T_f = i \cdot K_f \cdot m \), where \( K_f \) is the cryoscopic constant for water. Calculate \( \Delta T_f \) for each solution.
4. insert step 4> Use the boiling point elevation formula: \( \Delta T_b = i \cdot K_b \cdot m \), where \( K_b \) is the ebullioscopic constant for water. Calculate \( \Delta T_b \) for each solution.
5. insert step 5> Determine the new freezing and boiling points by subtracting \( \Delta T_f \) from the normal freezing point of water (0°C) and adding \( \Delta T_b \) to the normal boiling point of water (100°C).

Key Concepts

Colligative Properties

Colligative properties are physical properties of solutions that depend on the number of solute particles in a given amount of solvent, rather than the identity of the solute. These properties include boiling point elevation and freezing point depression, which are crucial for calculating the changes in phase transitions of solutions when solutes are added.

Dissociation of Ionic Compounds

Ionic compounds, such as FeCl3 and KCl, dissociate into their constituent ions when dissolved in water. This dissociation increases the number of solute particles in the solution, which directly affects the colligative properties. For example, FeCl3 dissociates into four ions (one Fe³⁺ and three Cl⁻), while KCl dissociates into two ions (one K⁺ and one Cl⁻).

Molality and Mass Percent Concentration

Molality is a measure of the concentration of a solute in a solution, defined as the number of moles of solute per kilogram of solvent. In contrast, mass percent concentration expresses the mass of solute as a percentage of the total mass of the solution. Understanding these concepts is essential for accurately calculating the freezing and boiling points of the solutions mentioned in the question.