Question

A chemical reaction is in equilibrium. Addition of a catalyst would not result in (1) the rates of forward and backward reactions are equally altered (2) a new reaction pathway to reaction (3) attainment of equilibrium quickly (4) increase in the amount of heat evolved in the reaction

Short answer

(4) increase in the amount of heat evolved in the reaction

Step-by-step solution

Identify the role of a catalyst

A catalyst speeds up both the forward and backward reactions in a chemical equilibrium without being consumed in the process.

Determine how a catalyst affects reaction rates

A catalyst equally increases the rates of both the forward and backward reactions, leading to faster attainment of equilibrium.

Analyze the reaction pathway

A catalyst provides an alternative reaction pathway with a lower activation energy, facilitating the reaction to proceed faster.

Evaluate the heat evolution aspect

A catalyst does not affect the thermodynamics of the reaction, meaning it does not change the amounts of reactants or products, nor the amount of heat evolved.

Select the correct answer

Based on the analysis, the addition of a catalyst would not increase the amount of heat evolved in the reaction.

Key concepts

reaction kinetics

Reaction kinetics is the study of the rates at which chemical reactions occur. The rate of a chemical reaction depends on factors such as temperature, concentration, and the presence of a catalyst. A catalyst is a substance that speeds up a chemical reaction without being consumed. In catalyzed reactions, both the forward and backward reactions are accelerated, leading to faster equilibrium. The rates of both directions of the reaction increase equally, maintaining the ratio of the concentrations of reactants and products at equilibrium.

chemical equilibrium

Chemical equilibrium occurs when the rates of the forward and backward reactions are equal, resulting in no net change in the concentrations of reactants and products. In this state, the reaction continues to proceed in both directions, but the concentrations remain constant. The addition of a catalyst helps the system reach equilibrium more quickly but does not change the position of the equilibrium. Catalysts hasten the process by providing an alternative pathway with a lower activation energy, allowing the reaction to proceed at a faster rate.

activation energy

Activation energy is the minimum energy required for a chemical reaction to occur. It represents the energy barrier that must be overcome for reactants to be converted into products. Catalysts work by lowering the activation energy, thereby increasing the rate at which the reaction proceeds. By providing an alternative pathway with lower activation energy, a catalyst allows more particles to have sufficient energy to react, thus speeding up the reaction. This applies to both the forward and backward reactions in a system at equilibrium. Remember, lowering activation energy does not affect the overall energy change (enthalpy) of the reaction.

thermodynamics

Thermodynamics deals with the heat and energy changes associated with chemical processes. When a reaction is in equilibrium, the thermodynamic properties such as enthalpy and entropy remain unchanged by the addition of a catalyst. A catalyst does not alter the amounts of reactants and products, nor does it affect the heat evolved or absorbed during the reaction. It influences only the rate at which equilibrium is achieved by lowering the activation energy. Thus, while catalysts are crucial for speeding up reactions, they do not alter the fundamental thermodynamic properties of the chemical system.