Colligative properties are special characteristics of solutions that depend only on the number of dissolved particles, not on what those particles actually are. Whether we dissolve sugar, salt, or any other substance, what matters is how many particles we have in the solution.
There are four main colligative properties. First is tonoscopy, where vapor pressure decreases. Second is ebullioscopy, where boiling point increases. Third is cryoscopy, where freezing point decreases. Fourth is osmometry, which involves osmotic pressure. All these effects occur because solute particles interfere with the normal behavior of the solvent.
Let's look at boiling point elevation with a practical example. Pure water boils at one hundred degrees Celsius. When we add salt, the dissolved particles interfere with the water molecules trying to escape as vapor. This means we need more energy, or higher temperature, to make the solution boil. The mathematical relationship shows that the temperature increase depends on the concentration and number of particles formed.
An important factor in colligative properties is ionic dissociation. When ionic compounds dissolve, they break apart into individual ions. For example, sodium chloride dissociates into sodium and chloride ions, creating two particles from one compound. Calcium chloride creates three particles: one calcium ion and two chloride ions. This means ionic solutions have stronger colligative effects than molecular solutions at the same concentration, because they produce more particles.
To summarize colligative properties: they depend only on the number of dissolved particles, not their identity. The four main types affect vapor pressure, boiling and freezing points, and create osmotic pressure. Ionic compounds have stronger effects because they dissociate into multiple particles. These properties have many practical applications in everyday life and industry.