FACTORS AFFECTING RATE OF REACTION:

The rate of a chemical reaction, which measures how quickly reactants are consumed or products are formed, is influenced by several factors. Understanding these factors helps in controlling and optimizing reaction rates. Here are the key factors affecting the rate of a reaction:

1. Nature of Reactants:The chemical nature of the reactants involved in a reaction plays a significant role. Some reactions occur more readily than others due to the inherent reactivity of the substances involved. For example, reactions between highly reactive elements or compounds tend to proceed at faster rates compared to reactions involving less reactive species.
2. Concentration:The concentration of reactants affects the rate of a reaction. Generally, an increase in reactant concentration leads to an increase in the reaction rate. This is because a higher concentration provides more reactant particles, leading to a higher collision frequency and an increased likelihood of successful collisions.
3. Temperature:The rate of reaction increases with the increase in temperature. In most cases, the rate of reaction becomes nearly double for 10⁰ rise in temperature. In some cases, reactions do not take place at room temperature but take place at higher temperatures.
4. Pressure (for gases): In the case of gaseous reactants, pressure can influence the reaction rate, particularly for reactions involving gases. Increasing the pressure of gaseous reactants can enhance the reaction rate by increasing the collision frequency between gas molecules.
5. Surface Area: In reactions involving solid reactants, the surface area of the solid can significantly impact the reaction rate. A larger surface area provides a more exposed area for reactant particles to interact, leading to more collisions and a faster reaction rate. Therefore, finely divided or powdered forms of solids tend to react faster compared to bulky or solid pieces.
6. Catalysts:Catalysts are substances that accelerate a reaction by providing an alternative reaction pathway with lower activation energy. They increase the rate of reaction without being consumed in the process. Catalysts can significantly enhance reaction rates and are widely used in various industrial and biological processes.
7. Presence of Inhibitors: Inhibitors are substances that decrease the rate of a reaction. They work by interfering with the reaction mechanism, reducing the effectiveness of collisions, or inhibiting the formation of active intermediates. Inhibitors are often used to control reaction rates or to prevent unwanted reactions.

Understanding and manipulating these factors allow scientists and engineers to control and optimize reaction rates for various applications, ranging from industrial processes to pharmaceutical synthesis and energy production.

Identify the false statement in the below

Rate of reaction increases with increase in time

The correct answer is option 4. Rate of reaction increases with increase in time.

Let us delve deeper into each factor affecting the rate of reaction and clarify why the statement regarding time is false:

Factors Affecting Rate of Reaction

Temperature:

Increasing the temperature generally increases the rate of reaction. This is because higher temperatures provide reactant molecules with more kinetic energy. According to the collision theory, this results in more frequent collisions between reactant molecules and a greater proportion of collisions having sufficient energy to overcome the activation energy barrier. Therefore, reactions proceed faster at higher temperatures.

Concentration of Reactants:

The rate of reaction increases with an increase in the concentration of reactants. This is because higher concentrations lead to more reactant molecules being present in a given volume, increasing the frequency of collisions between reactant molecules. More collisions mean a higher likelihood of effective collisions that result in the formation of products.

Presence of Catalysts:

Catalysts increase the rate of reaction by providing an alternative reaction pathway with a lower activation energy. This lowers the energy barrier that reactant molecules must overcome to form products. Catalysts themselves are not consumed in the reaction and can be reused, making them effective in accelerating reactions without being permanently altered.

Time:

The rate of reaction does not increase with time; rather, it typically decreases over time. Initially, when reactants are plentiful, the rate of reaction is highest. As the reaction progresses, reactants are consumed, and their concentrations decrease. Consequently, the frequency of collisions between reactant molecules decreases, leading to a decrease in the rate of reaction. Eventually, the reaction may reach equilibrium, where the rate of the forward reaction equals the rate of the reverse reaction, or the reaction may be completed when all reactants are converted into products.

Clarification of the False Statement

The statement "Rate of reaction increases with increase in time" is false because it misinterprets the nature of reaction kinetics. Time itself does not increase the rate of reaction. Instead, the rate of reaction typically decreases over time due to the consumption of reactants. This is a natural consequence of reactants being converted into products until equilibrium or completion is reached.

Summary

Understanding the factors affecting the rate of reaction—temperature, concentration of reactants, presence of catalysts, and the role of time—is crucial in chemistry. While the first three factors generally increase the rate of reaction, time does not; rather, it reflects the progression of the reaction towards its endpoint as reactants are consumed and products are formed.

Therefore, the false statement among the options provided is indeed: Rate of reaction increases with increase in time.