Question

the relative lowering of vapour pressure is delta p by P not here delta P is​

Answer 1

Answer:

In chemistry, colligative properties are those properties of solutions that depend on the ratio of the number of solute particles to the number of solvent molecules in a solution, and not on the nature of the chemical species present.[1] The number ratio can be related to the various units for concentration of solutions, for example, molarity, molality, normality (chemistry), etc. The assumption that solution properties are independent of nature of solute particles is only exact for ideal solutions, and is approximate for dilute real solutions. In other words, colligative properties are a set of solution properties that can be reasonably approximated by assuming that the solution is ideal.

Only properties which result from the dissolution of nonvolatile solute in a volatile liquid solvent are considered.[2] They are essentially solvent properties which are changed by the presence of the solute. The solute particles displace some solvent molecules in the liquid phase and therefore reduce the concentration of solvent, so that the colligative properties are independent of the nature of the solute. The word colligative is derived from the Latin colligatus meaning bound together.[3] This indicates that all colligative properties have a common feature, namely that they are related only to the number of solute molecules relative to the number of solvent molecules and not to the nature of the solute.[4]

Colligative properties include:

Relative lowering of vapour pressure

Elevation of boiling point

Depression of freezing point

Osmotic pressure

For a given solute-solvent mass ratio, all colligative properties are inversely proportional to solute molar mass.

Measurement of colligative properties for a dilute solution of a non-ionized solute such as urea or glucose in water or another solvent can lead to determinations of relative molar masses, both for small molecules and for polymers which cannot be studied by other means. Alternatively, measurements for ionized solutes can lead to an estimation of the percentage of dissociation taking place.

Colligative properties are mostly studied for dilute solutions, whose behavior may be approximated as that of an ideal solution. In fact, all of the properties listed above are only colligative in the dilute limit: at higher concentrations, the freezing point depression, boiling point elevation, vapour pressure elevation or depression, and osmotic pressure are all dependent on the chemical nature of the solvent and the solute.