HF is a weak electrolyte and HBr is a strong electrolyte. Which of the curves in the figure represents the change in the boiling point of an aqueous solution when 1 mole of HF is added to 1 kg of water, and which represents the change when 1 mol of HBr is added?

Verified step by step guidance

1. Identify that HF is a weak electrolyte and HBr is a strong electrolyte.
2. Recall that strong electrolytes dissociate completely in solution, while weak electrolytes do not.
3. Understand that the boiling point elevation is a colligative property, which depends on the number of particles in solution.
4. Recognize that HBr, being a strong electrolyte, will produce more ions in solution compared to HF, leading to a greater boiling point elevation.
5. Conclude that the curve with the greater change in boiling point corresponds to the addition of HBr, while the lesser change corresponds to HF.

Key Concepts

Electrolytes

Electrolytes are substances that dissociate into ions when dissolved in water, allowing the solution to conduct electricity. They are classified as strong or weak based on their degree of ionization. Strong electrolytes, like HBr, completely dissociate into ions, while weak electrolytes, like HF, only partially dissociate, affecting their colligative properties.

Colligative Properties

Colligative properties are 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. The more particles present in solution, the greater the effect on these properties, which is crucial for understanding the differences between HF and HBr solutions.

Boiling Point Elevation

Boiling point elevation is a colligative property that describes how the boiling point of a solvent increases when a solute is added. The extent of this elevation is directly proportional to the number of solute particles in the solution. In the case of adding 1 mole of HF versus 1 mole of HBr, the strong electrolyte (HBr) will produce more ions in solution, resulting in a greater increase in boiling point compared to the weak electrolyte (HF).