SIFAT KOLIGATIF LARUTAN (Part 3), Kenaikan Titik Didih Larutan

Introduction

This tutorial aims to explain the concept of boiling point elevation in solutions, a key aspect of colligative properties in chemistry. Understanding this phenomenon is essential for accurately calculating boiling points of solutions, which has practical applications in various scientific fields.

Step 1: Understand Colligative Properties

• Colligative properties depend on the number of solute particles in a solution, not the type of solute.
• Key colligative properties include:
  • Boiling point elevation
  • Freezing point depression
  • Vapor pressure lowering
  • Osmotic pressure

Step 2: Learn About Boiling Point Elevation

• Boiling point elevation occurs when a non-volatile solute is added to a solvent, resulting in a higher boiling point than that of the pure solvent.
• The formula to calculate the boiling point elevation (( \Delta T_b )) is: [ \Delta T_b = i \cdot K_b \cdot m ] Where:
  • ( \Delta T_b ) = change in boiling point
  • ( i ) = van 't Hoff factor (number of particles the solute breaks into)
  • ( K_b ) = ebullioscopic constant of the solvent
  • ( m ) = molality of the solution

Step 3: Calculate the Boiling Point Elevation

1. Identify the Solvent and Solute:

   • Determine the solvent (e.g., water) and the solute (e.g., salt).

2. Determine the van 't Hoff Factor:

   • For example, sodium chloride (NaCl) dissociates into two ions (Na+ and Cl-), so ( i = 2 ).

3. Find the Ebullioscopic Constant:

   • Each solvent has a specific ( K_b ) value. For water, ( K_b ) is approximately 0.512 °C kg/mol.

4. Calculate the Molality of the Solution:

   • Molality (( m )) is calculated as: [ m = \frac{\text{moles of solute}}{\text{mass of solvent in kg}} ]

5. Apply the Boiling Point Elevation Formula:

   • Substitute values into the formula to find ( \Delta T_b ).
   • Example calculation:
     • If you have 1 mole of NaCl in 1 kg of water: [ \Delta T_b = 2 \cdot 0.512 \cdot 1 = 1.024°C ]
   • The new boiling point of the solution would be: [ 100°C + 1.024°C = 101.024°C ]

Conclusion

Understanding boiling point elevation is crucial for predicting how solutes affect the properties of solvents. By following the steps outlined in this tutorial, you can calculate the boiling point of any solution using its components. To deepen your knowledge, consider reviewing previous materials on colligative properties and their calculations.