12th ScienceChemistryHSC Projects

Chemistry Project On Colligative Properties Of Class 12th


Colligative properties, those fundamental concepts in chemistry that govern the behavior of solutions, are a subject of great significance. These properties depend solely on the concentration of solute particles, regardless of the specific nature of the solute. Within this project, we delve into the four primary colligative properties: vapor pressure lowering, boiling point elevation, freezing point depression, and osmotic pressure. Understanding these properties is paramount in the world of chemistry, and their applications span various industries and everyday scenarios.

Theoretical Background

Vapor Pressure Lowering
When we introduce a non-volatile solute to a volatile solvent, we observe a decrease in the vapor pressure of the solvent above the resulting solution. This phenomenon finds its explanation in Raoult’s Law, which posits that the vapor pressure of a solution is directly linked to the mole fraction of the solvent within it.

Boiling Point Elevation
The incorporation of a non-volatile solute into a solvent manifests as an increase in the boiling point of that solvent. This outcome arises from the need for the vapor pressure of the solution to align with external pressure (typically 1 atm) for boiling to ensue. The extent of the boiling point increase is directly proportional to the solute’s concentration and can be computed using the ebullioscopic constant.

Freezing Point Depression
When a non-volatile solute resides in a solvent, it leads to a reduction in the solvent’s freezing point. This effect occurs because the solute disrupts the formation of the solvent’s crystal lattice structure. The magnitude of the freezing point drop is directly tied to the solute concentration and can be computed utilizing the cryoscopic constant.

Osmotic Pressure
Osmotic pressure is the force needed to halt the flow of solvent molecules through a semipermeable membrane when a solute is present on one side of the barrier. This pressure is proportional to the solute concentration and can be calculated using the van’t Hoff factor.

Experimental Demonstration

Materials and Equipment

For Vapor Pressure Lowering Experiment:

  • Solvent: Water (H2O)
  • Solute: Common salt (NaCl)
  • Measuring cylinders
  • Glass containers
  • Thermometer

For Boiling Point Elevation Experiment

  • Solvent: Acetone (C3H6O)
  • Solute: Camphor (C10H16O)
  • Boiling point apparatus
  • Thermometer
  • Beakers

For Freezing Point Depression Experiment

  • Solvent: Naphthalene (C10H8)
  • Solute: Camphor (C10H16O)
  • Freezing point apparatus
  • Thermometer
  • Beakers

For Osmotic Pressure Experiment

  • Solvent: Sugar solution (Sucrose – C12H22O11)
  • Semipermeable membrane (e.g., dialysis tubing)
  • Osmotic pressure apparatus
  • Beakers
  • Measuring cylinders


Vapor Pressure Lowering Experiment

  1. Prepare a known concentration of saltwater solution by dissolving a measured amount of NaCl in water.
  2. Measure the vapor pressure of pure water and the saltwater solution using glass containers and a thermometer.
  3. Compare the results to observe the vapor pressure lowering effect.

Boiling Point Elevation Experiment

  1. Prepare a solution of camphor in acetone with a known concentration.
  2. Set up a boiling point apparatus, heat pure acetone, and record its boiling point.
  3. Heat the camphor-acetone solution and record its boiling point.
  4. Calculate the change in boiling point and relate it to the solute concentration.

Freezing Point Depression Experiment

  1. Create a solution of camphor in naphthalene with a known concentration.
  2. Use a freezing point apparatus to measure the freezing point of pure naphthalene.
  3. Measure the freezing point of the camphor-naphthalene solution.
  4. Calculate the change in freezing point and correlate it with the solute concentration.

Osmotic Pressure Experiment

  1. Prepare sugar solutions of varying concentrations using sucrose and water.
  2. Set up an osmotic pressure apparatus with a semipermeable membrane.
  3. Measure the osmotic pressure for each solution and analyze the data.

Data Collection and Analysis
Record all experimental data and perform calculations to verify the colligative properties. Create graphs and tables to visualize the relationships between concentration and property changes.

Real-world Applications

Antifreeze in Automobiles
Colligative properties, particularly freezing point depression, are utilized in antifreeze solutions for automobiles. By adding antifreeze to the radiator, the freezing point of the coolant is lowered, preventing engine damage in cold temperatures.

Salting Roads in Winter
Salt (sodium chloride) is spread on icy roads during winter to lower the freezing point of water, enabling ice to melt at lower temperatures and improving road safety.

Biological Systems
Colligative properties, especially osmotic pressure, play a crucial role in biological systems. Osmosis, a vital process for cells, is governed by osmotic pressure, allowing cells to maintain proper water balance.


Colligative properties stand as pivotal elements in comprehending the intricate behavior of solutions in the realm of chemistry. Their far-reaching influence spans from safeguarding car engines during the frigid winter months to upholding the integrity of biological cells. The exploration of colligative properties is not solely an academic pursuit; it is a practical necessity in our daily lives.


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Atkins, P., & de Paula, J. (2018). Atkins’ Physical Chemistry (11th ed.). Oxford University Press.
Chang, R. (2010). Chemistry (11th ed.). McGraw-Hill.
Petrucci, R. H., Herring, F. G., & Madura, J. D. (2016). General.

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