Question

The process which is catalysed by one of the product is called: (a) acid-base catalysis (b) autocatalysis (c) negative catalysis (d) homogeneous catalysis

Short answer

The process which is catalysed by one of the product is called autocatalysis (b).

Step-by-step solution

Understanding the Definitions

To find the correct answer, we need to understand the definitions of each type of catalysis. Acid-base catalysis involves a transfer of protons, autocatalysis happens when one of the products of the reaction serves as a catalyst for the same reaction, negative catalysis refers to a decrease in reaction rate due to the presence of an additional substance, and homogeneous catalysis occurs when the catalyst is in the same phase as the reactants.

Identifying the Correct Type of Catalysis

Since the exercise asks about the process where one of the products acts as a catalyst for the same reaction, the correct term for this type of catalysis is autocatalysis.

Key concepts

Catalysis

Catalysis is a fundamental concept in chemistry that involves the acceleration of a chemical reaction by a substance called a catalyst. A catalyst is unique because it is not consumed in the reaction; rather, it speeds up the rate at which the reactants convert into products without undergoing any permanent changes itself. Essentially, it lowers the activation energy required for a reaction, thus allowing the reaction to occur more readily at a given temperature.

The importance of catalysis cannot be overstated; it's vital in various industries, from the manufacture of chemicals and pharmaceuticals to the development of new materials and the protection of the environment through catalytic converters in vehicles. Catalysis is broadly categorized by the nature of the catalyst and the reaction conditions, leading to different types such as acid-base catalysis, autocatalysis, negative catalysis, and homogeneous catalysis, each with unique characteristics and applications.

Acid-Base Catalysis

Acid-base catalysis occurs when an acid or a base speeds up a chemical reaction. This form of catalysis revolves around the transfer of protons (H⁺) between the catalyst and the reactant. An acid catalyst donates protons to the reactant, while a base catalyst accepts protons from the reactant. This proton transfer can significantly stabilize transition states and intermediates during the reaction, hence accelerating the overall process.

Acid-base catalysis is widely observed in biochemical reactions within our bodies – for instance, in the digestion of food where enzymes act as biocatalysts through acid-base mechanisms. Understanding this type of catalysis is crucial for designing pharmaceuticals and synthetic processes that are both efficient and sustainable.

Negative Catalysis

Negative catalysis, also known as inhibition, stands in contrast to the typical role of a catalyst. In negative catalysis, the presence of a substance actually slows down the reaction rate. This occurs when the inhibitor binds to a reactant, blocking active sites or forming a complex that is less reactive than the original reactant.

Negative catalysis plays a significant role in controlling the speed of chemical reactions where a slower rate is beneficial. This is particularly important in preventing runaway reactions in industrial processes or controlling the release rate of drugs in pharmaceuticals. Moreover, understanding negative catalysis is essential for the deactivation of harmful substances in pollution control strategies.

Homogeneous Catalysis

Homogeneous catalysis refers to scenarios where the catalyst and the reactants are in the same phase, typically both in the liquid or gas phase. This characteristic ensures that the interacting molecules can mix uniformly, thus facilitating efficient contact between the catalyst and the reactants. A common example of homogeneous catalysis is the use of acid in the transesterification process for producing biodiesel, where all components are in the liquid phase.

The advantage of homogeneous catalysis lies in its ability to be finely tuned for optimal reactivity and selectivity, leading to higher yields and fewer side products. However, the challenge often lies in separating the catalyst from the final product, which has driven research into recyclable homogeneous catalysts that can be effortlessly recovered and reused.