List the following aqueous solutions in order of increasing boiling point: 0.120 m glucose, 0.050 m LiBr, 0.050 m Zn(NO₃)₂.

Verified step by step guidance

1. Identify the colligative property involved: Boiling point elevation is a colligative property, which depends on the number of solute particles in a solution.
2. Determine the van 't Hoff factor (i) for each solute: Glucose (C_6H_{12}O_6) is a non-electrolyte, so i = 1. LiBr is an electrolyte that dissociates into Li^+ and Br^-, so i = 2. Zn(NO_3)_2 dissociates into Zn^{2+} and 2 NO_3^-, so i = 3.
3. Calculate the effective molality for each solution: Multiply the molality (m) by the van 't Hoff factor (i) for each solution. For glucose, it's 0.120 m * 1. For LiBr, it's 0.050 m * 2. For Zn(NO_3)_2, it's 0.050 m * 3.
4. Compare the effective molalities: The solution with the highest effective molality will have the highest boiling point, and the one with the lowest effective molality will have the lowest boiling point.
5. List the solutions in order of increasing boiling point based on their effective molalities.

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, freezing point depression, vapor pressure lowering, and osmotic pressure. In this context, the boiling point elevation is crucial for determining the order of the solutions based on their molal concentrations.

Boiling Point Elevation

Boiling point elevation occurs when a non-volatile solute is added to a solvent, resulting in an increase in the boiling point of the solution compared to the pure solvent. The extent of this elevation is directly proportional to the molality of the solute and the van 't Hoff factor (i), which accounts for the number of particles the solute dissociates into. Thus, solutions with higher concentrations of solute particles will have higher boiling points.

Van 't Hoff Factor (i)

The van 't Hoff factor (i) represents the number of particles into which a solute dissociates in solution. For example, glucose does not dissociate (i=1), while LiBr dissociates into two ions (Li+ and Br-, i=2), and Zn(NO3)2 dissociates into three ions (Zn2+ and two NO3-, i=3). This factor is essential for calculating the effective concentration of solute particles, which influences the boiling point elevation of the solution.