Question

According to Le Châtelier's principle, when a large excess of a gaseous reactant is added to a reaction system at equilibrium, the amounts of products ____.

Short answer

According to Le Châtelier's principle, when a large excess of a gaseous reactant is added to a reaction system at equilibrium, the amounts of products increase.

Step-by-step solution

Understand the reaction system at equilibrium

At equilibrium, the rate of the forward reaction equals the rate of the reverse reaction. This means that the concentrations of reactants and products remain constant.

Analyze the effect of adding a large excess of a gaseous reactant

According to Le Châtelier's principle, adding a large excess of a gaseous reactant to the system will cause the system to adjust in order to counteract the change and restore equilibrium. In this case, the system will adjust by shifting the reaction to favor the formation of products - it will shift the position of equilibrium towards the products side.

Determine the changes in the amounts of products as a result of the shift in equilibrium

As a consequence of the shift in equilibrium towards the products side, the concentrations of the products will increase while the concentrations of the reactants will decrease. Thus, the amounts of products will increase. So, the correct answer is: According to Le Châtelier's principle, when a large excess of a gaseous reactant is added to a reaction system at equilibrium, the amounts of products increase.

Key concepts

Equilibrium

Equilibrium in a chemical reaction refers to the state where the rates of the forward and reverse reactions are equal. This balance results in the concentrations of both reactants and products remaining stable over time. At equilibrium, the system is dynamically balanced, meaning that although the reactions continue to occur, there is no net change in the concentrations of reactants and products.
**Dynamic Equilibrium**
- Even though concentrations remain constant, the reactions are ongoing. - Forward and reverse reactions happen at the same rate, maintaining stability.
In such a system, any change in conditions, such as concentration, temperature, or pressure, can disrupt the balance. This is where Le Châtelier's principle comes into play, providing insight into how a system at equilibrium reacts to changes.

Gaseous Reactant

When discussing the concept of a gaseous reactant, it is crucial to understand the unique role gases play in chemical reactions. Gases, unlike liquids or solids, occupy the entire volume of their container. This characteristic allows gaseous reactants to engage and disperse quickly in a reaction, impacting the reaction's equilibrium state.
- **High Responsiveness:** Any change in the concentration of a gaseous reactant can swiftly alter a reaction's dynamics. - **Effect on Equilibrium:** Adding more of a gaseous reactant, for instance, can push the reaction equilibrium, causing a shift.
In the context of Le Châtelier's principle, adding an excess of a gaseous reactant causes the system to respond by attempting to counteract the change. Therefore, if more of a gaseous reactant is added, the equilibrium will shift in favor of the reaction that consumes the excess reactant, often leading to an increased formation of products.

Reaction Shift

A reaction shift is an adjustment that a chemical reaction at equilibrium undergoes in response to a change in conditions such as concentration, temperature, or pressure, as described by Le Châtelier's principle. A key point to remember is that the shift moves the equilibrium towards the direction that helps counterbalance the imposed change.
**Understanding Reaction Shifts**
- **Direction of Shift:** The equilibrium can shift either to the right (favoring products) or to the left (favoring reactants), depending on how the system compensates for the change. - **Influencing Factors:** These include changes in - Concentration: More reactant leads to a shift toward products. - Temperature: Influences reaction course depending on whether reactions are exothermic or endothermic. - Pressure: Affects reactions with gaseous reactants found under varying conditions.
In the case of adding a large excess of a gaseous reactant, the system compensates by shifting the equilibrium towards products, thereby increasing the product's concentration until a new equilibrium is established. This adjustment highlights the dynamic nature of chemical equilibrium and the system's tendency to maintain stability.