Animated Solution for Chemistry - Surface Chemistry: A colloidal system consisting of a gas dispersed in a solid is called a/an

The study of surface chemistry introduces us to the fascinating world of colloidal systems—mixtures that bridge the gap between true solutions and coarse suspensions. In this problem, we are asked to identify the specific term for a colloid where a gas is dispersed within a solid. Let's break down the terminology and the classification to arrive at the correct answer.

Before we classify the specific system, we must understand the two fundamental components that make up any colloid: 1. Dispersed Phase (DP): This is the substance that is distributed or scattered in the form of microscopic particles. It is analogous to the solute in a true solution. 2. Dispersion Medium (DM): This is the continuous medium in which the dispersed phase is scattered. It acts much like the solvent in a true solution.

In our given question, the problem explicitly states that a gas is dispersed in a solid. Therefore, we can clearly identify our components: Dispersed Phase: Gas Dispersion Medium: Solid

Imagine a rigid block of material that, upon closer inspection, is riddled with tiny, trapped pockets of air. A classic real-world example of this is a pumice stone, which is formed from rapidly cooling volcanic lava that traps gas bubbles within its solid matrix.

To find the official name for this specific combination, we rely on the standard IUPAC classification of colloidal systems. This classification is based entirely on the physical states (solid, liquid, or gas) of the dispersed phase and the dispersion medium.

Let's look at the relevant section of the classification table:

As we can see from the table, when a gas is trapped within a solid dispersion medium, the resulting colloidal system is officially termed a solid sol.

Matching our analysis with the given options, we find that a gas dispersed in a solid corresponds perfectly to option (a), solid sol.

It is highly beneficial to memorize the other common colloidal types as well. For instance, if the question had asked about a liquid dispersed in a solid (like jelly or cheese), the answer would be a gel. If it asked about a solid or liquid dispersed in a gas (like smoke or fog), it would be an aerosol. And if it asked about a gas dispersed in a liquid (like whipped cream), it would be a foam.

Mastering this classification table is a guaranteed way to secure quick and easy marks in your chemistry exams!