Question

The effect of pressure on adsorption is high if: (a) temperature is low (b) temperature is high (c) temperature is very high (d) larger charcoal piece is taken

Short answer

The effect of pressure on adsorption is high when the temperature is low.

Step-by-step solution

Understand the effect of temperature on adsorption

Adsorption is generally an exothermic process, meaning it releases heat. According to Le Chatelier's principle, if a process is exothermic, increasing temperature will decrease the extent of the reaction. Conversely, lowering temperature favors the exothermic process. Therefore, adsorption increases with a decrease in temperature.

Compare the options based on the knowledge of adsorption

Reviewing the options, we need to identify which scenario increases adsorption. A lower temperature makes adsorption more favorable, while higher temperatures make it less favorable. The size of the charcoal piece is not directly related to temperature effects, though larger surface areas do generally increase adsorption. For this question, we are specifically looking at the effect due to temperature.

Choose the correct option

Since adsorption is higher where the temperature is low and given that options (b) and (c) indicate high or very high temperature and option (d) is unrelated to temperature, the correct answer must be (a) temperature is low.

Key concepts

Le Chatelier's Principle

To comprehend the delicate balance of chemical reactions, Le Chatelier's principle is a fundamental guide. It tells us that if a dynamic equilibrium within a closed system is disturbed by changes in conditions, such as pressure, temperature, or concentration of components, the system will adjust itself to counteract the disturbance and restore a new equilibrium.

Imagine a seesaw where two children are perfectly balanced. If one child suddenly jumps off, the other child would go crashing down. But if that child on the ground quickly adds some weight, like a backpack, to their side, the seesaw might come back to a more balanced state. That's essentially what Le Chatelier's principle suggests about reactions — they naturally 'push back' to find balance again.

Exothermic Process

An exothermic process is akin to a warm embrace, releasing energy to its surroundings, most commonly in the form of heat. It's like a log burning in a fireplace, where the energy stored in the wood is given off as heat and light, warming the room.

In the context of adsorption, when a substance adheres to the surface of a solid, the solid captures the substance's energy. This energy release often enhances the bonding between the adsorbed molecules and the surface they cling to. The warmth we feel is the physical manifestation of the process, serving as a testimony to the energy transferred during the adsorption.

Effect of Temperature on Adsorption

Temperature acts like a puppeteer to the process of adsorption. In most cases, higher temperatures give energy to the molecules, causing them to move more vigorously, which can dislodge them from the surfaces they are adsorbed onto. This is why cooling down a system often increases adsorption — the hustle and bustle of the molecules lessen, and they tend to stick to surfaces more readily.

Remember our warm fireplace? If it's too hot, people move away from it to cool down. Similarly, increase the temperature, and adsorbed molecules are more likely to 'move away' from the surface. In colder conditions, these molecules are less energetic and more likely to 'stay seated' on their adsorbed perches. Thus, the chillier the system, the stronger the embrace between the molecule and the surface.