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.

The reactions whose rate increases by subjecting to light are called

All of these

The correct answer is option 4. All of these.

Let us delve into each of these terms:

1. Photo-accelerated reactions:

In photo-accelerated reactions, the rate of the reaction is directly accelerated by exposure to light. However, unlike photo-catalyzed reactions, there may not be a specific catalyst involved. Instead, the molecules involved in the reaction may have electronic states that are excited by light, leading to increased reaction rates.

2. Photo-catalyzed reactions:

In photo-catalyzed reactions, light is used to excite a catalyst, which then participates in the reaction without being consumed. This catalyst helps lower the activation energy barrier for the reaction, making it proceed at a faster rate. The catalyst itself remains unchanged at the end of the reaction and can continue to facilitate multiple reaction cycles.

3. Photosensitized reactions:

Photosensitized reactions involve the presence of a photosensitizer, which is a molecule capable of absorbing light energy and transferring it to other molecules. The photosensitizer is typically not consumed in the reaction but plays a crucial role in initiating or accelerating the reaction by transferring energy to reactant molecules. This leads to an increased rate of reaction compared to reactions that do not involve photosensitizers.

All of these terms describe reactions where light plays a significant role in increasing the rate of the reaction. Whether it's by directly accelerating the reaction, through the action of a catalyst excited by light, or via a photosensitizer transferring energy to reactants, light can facilitate chemical reactions in various ways.