Give reasons for the following.

• Elevation of boiling point of 1M KCl solution is nearly double than that of 1M sugar solution.

The elevation of the boiling point in a solution is influenced by the number of particles that are present in the solution. This phenomenon is known as boiling point elevation and is a colligative property, which depends on the concentration of solute particles rather than their identity.

Understanding the Differences

When comparing a 1M KCl solution to a 1M sugar solution, the key factor is how these substances dissociate in water:

• KCl (Potassium Chloride): This compound is an ionic salt that dissociates into two ions in solution: K⁺ and Cl^-. Therefore, a 1M KCl solution produces 2 moles of particles per mole of solute.
• Sugar (C₁₂H₂₂O₁₁): Sugar is a molecular compound that does not dissociate in solution. A 1M sugar solution remains as 1 mole of particles.

Impact on Boiling Point Elevation

Since the boiling point elevation is directly proportional to the number of solute particles, the KCl solution, which has 2 moles of particles, will elevate the boiling point nearly twice as much as the sugar solution, which has only 1 mole of particles. This results in a greater boiling point elevation for the KCl solution.

Summary

In summary, the nearly double elevation of the boiling point in a 1M KCl solution compared to a 1M sugar solution is due to the dissociation of KCl into two ions, leading to a higher concentration of solute particles in the KCl solution.