Question

Parachor is a property which is (a) additive-cum-constitutive (b) colligative (c) additive (d) none

Short answer

The correct choice is (a) additive-cum-constitutive.

Step-by-step solution

Understanding the terms in the options

First, understand the meaning of the options: additive-cum-constitutive, colligative, additive, none.- Additive-cum-constitutive: This refers to a property that is both additive (dependent on the sum of the contributing individual components) and constitutive (dependent on the physical and chemical characteristics of the system).- Colligative: Refers to properties which depend on the number of solute particles, irrespective of their nature, in a given amount of solvent.- Additive: Only dependent upon the total sum of the individual components' contribution.- None: The property does not fit any of the above descriptions.

Identify the Property of Parachor

The property of parachor correlates the volume change in a system during the formation of a surface with the change in the surface tension. It is often used to predict the behavior of complex molecules when the behavior of individual components is known. By its definition, it is clear that parachor must be an additive property, but it also depends on the chemical characteristics of the system, showing it to be constitutive as well.

Check for the Correct Option

With the considerations from Step 2, the parachor is both an additive and constitutive property. Hence, from the available options, additive-cum-constitutive is the correct choice.

Key concepts

Additive-Cum-Constitutive Property

Imagine assembling a complex machine; each part contributes to the overall function, but the way they fit and interact is just as important. This is similar to an additive-cum-constitutive property in chemistry. Parachor, for instance, embodies this dual characteristic.

It is additive because it is influenced by the individual molecular contributions to the total volume of the system. But there's more to the story. The constitutive aspect means that the physical and chemical nature of each molecule also plays a role. Think of it as a team sport: individual player statistics (additive) matter, but how they play as a team (constitutive) can change the outcome.

Colligative Properties

What do boiling point elevation, freezing point depression, and osmotic pressure have in common? They are all colligative properties, which depend on the number of particles dissolved in a solvent - not on what those particles are. Consider it like a crowd at a concert: it doesn't matter who the individuals are; the overall size of the crowd affects the atmosphere.

One common misconception might be to lump all solute-dependent properties under colligative. However, parachor is not a colligative property. Unlike colligative properties, parachor does take into account the type of particles, their interactions, and the resulting surface tension, not merely their presence or quantity in a solution.

Surface Tension

Ever seen water bead up on a waxy leaf or wondered how water striders walk on water? The answer lies in surface tension. It's the elastic tendency of liquids which makes them acquire the least surface area possible, a measure of how tightly the molecules at the surface are being 'pulled' together.

Parachor is deeply connected to this concept as it measures the impact of molecular changes on surface tension. With parachor, if you know the surface tension and volume of a molecule, you can predict these values for related complex molecules, a bit like recognizing family resemblances in features passed from parents to children.