Question

The dissociation of \(\mathrm{ClF}_{3}\) occurs as follows: \(2 \mathrm{ClF}_{\mathrm{g}} \rightleftharpoons \mathrm{Cl}_{\mathrm{g}}+\underset{\mathrm{g}}{3 \mathrm{~F}_{2}} \Delta \mathrm{H}=+\mathrm{ve}\) It is favoured by: (1) Addition of more fluorine (2) Increase of temperature (3) Increase of volume of the container (4) Adding of inertgas at constant pressure (a) I, II (b) II, III (c) I, II, III (d) II, III, IV

Short answer

The dissociation is favored by options (b) II, III and (d) II, III, IV.

Step-by-step solution

Understand the Reaction

The reaction given is the dissociation of \(2 \mathrm{ClF}_3\) into \(\mathrm{Cl}_2\) and \(3 \mathrm{F}_2\), with a positive \(\Delta \mathrm{H}\) indicating an endothermic reaction.

Determine Effect of Temperature Change

Since the reaction is endothermic \((\Delta \mathrm{H} = +)\), increasing the temperature will favor the forward direction by Le Chatelier's principle.

Consider the Effect of Volume Change

The reaction results in an increase in the number of gas molecules (from 2 moles of \(\mathrm{ClF}_3\) to 4 moles, \(\mathrm{Cl}_2 + 3 \mathrm{F}_2\)). Increasing the volume will cause the equilibrium to shift to the right, favoring dissociation.

Evaluate the Addition of Inert Gas at Constant Pressure

Adding an inert gas at constant pressure increases the volume of the container. This volume increase, as determined in Step 3, will favor the forward reaction.

Assess the Effect of Adding More Fluorine

Adding more \(\mathrm{F}_2\) would shift the equilibrium to the left to reduce the change, hence it does not favor dissociation.

Identify Favorable Conditions

From the analysis, increasing temperature, increasing volume, and adding inert gas at constant pressure will favor the dissociation reaction.

Key concepts

Le Chatelier's Principle

Le Chatelier's Principle is a fundamental concept in chemistry used to predict the behavior of a system at equilibrium under external changes. When a system at equilibrium is subjected to a change, such as a change in concentration, temperature, or pressure, the system will adjust itself to counteract the effect of the applied change, trying to restore a new equilibrium condition. Think of it as the system's way of keeping things balanced. For example, if a reaction at equilibrium involves gases, an increase in pressure will cause the equilibrium to shift towards the side with fewer gas molecules. Similarly, if we add more of a reactant or product, the system will shift in a direction that uses up the added components to re-establish equilibrium. Understanding this principle is key in predicting the behavior of chemical reactions when their equilibrium conditions are altered.

Endothermic Reaction

An endothermic reaction is a type of chemical process that absorbs energy from its surroundings, usually in the form of heat. This is indicated by a positive change in enthalpy (9H > 0). During an endothermic reaction, heat is taken in to break chemical bonds of the reactants, resulting in products that are higher in energy compared to the reactants. These reactions are often sensitive to temperature changes. For instance, if we increase the temperature of an endothermic reaction at equilibrium, it will absorb more heat and hence, the reaction will proceed in the forward direction to optimize energy absorption. A real-world example of endothermic reactions includes photosynthesis, where plants absorb sunlight to convert carbon dioxide and water into glucose and oxygen. Understanding this concept is crucial, especially for reactions at equilibrium like the dissociation of 2ClF_32. This awareness helps in manipulating conditions to favor certain reactions, whether in a laboratory or industrial setting.

Effect of Temperature on Equilibrium

Temperature is a vital factor in affecting chemical equilibrium. According to Le Chatelier's Principle, if you change the temperature of a system at equilibrium, the system will shift the position of equilibrium to counteract that change. For endothermic reactions, such as the dissociation of ClF₃, increasing temperature will drive the reaction towards the products, as it needs to absorb the additional heat. If you decrease the temperature, the reaction will shift towards the reactants as it releases heat. In contrast, exothermic reactions release heat, so increasing the temperature shifts the equilibrium towards the reactants, whereas decreasing the temperature will favor products. Understanding how temperature affects equilibrium allows chemists to control reaction directions, optimize yields, and improve industrial chemical processes, guiding essential decisions in practical applications and making processes more efficient.

Effect of Volume on Equilibrium

Volume changes can significantly influence reactions involving gases. If the volume of a gas reaction mixture at equilibrium is increased, the system will tend to shift towards the side with more moles of gas. This is because an increase in volume decreases pressure, and the system will attempt to adjust the pressure by favoring the side with more gas particles. In the reaction 2 ClF₃ 11 Cl0,+ 3 F₂, increasing the volume allows the system to shift to the right. This means the reaction will favor the side with more moles of gas (4 moles on the product side compared to the 2 moles on the reactant side). Conversely, if the volume is decreased, the reaction will shift towards the side with fewer moles of gas to try and increase the pressure. The effect of volume is especially crucial in processes where control of gas reactions is necessary, aiding in achieving desired reactions, understanding natural gas occurrences, or planning industrial applications.