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CBSE Class 11 » CBSE Class 11 Study Materials » Chemistry » A Study on Catalysis
CBSE

A Study on Catalysis

In chemistry, catalysis is the change in the rate of a chemical reaction, usually an acceleration.

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In chemistry, what is the definition of a catalyst

Catalysts are described in chemistry as chemicals that modify the rate of a reaction by altering the process’s course. In other words, they alter the reaction’s trajectory. The bulk of the time, a catalyst is used to speed up or raise the reaction rate. Catalysts are used to either break or repair chemical bonds between the atoms of different elements or compounds that are present in their respective molecules, according to a deeper level of examination. Catalysts are molecules that urge molecules to react, making the whole process easier and more efficient.

A Quick History of the Past

Catalysts, in their broadest sense, are anything that speeds up the pace at which a process happens. Chemist Elizabeth Fulhame was the first to examine the concept of catalysis, which she presented in her book in 1794, more than a century later. Her study on oxidation-reduction experiments inspired the material of this book.

Gottlieb Kirchhoff, a Russian chemist of German descent, discovered the first chemical reaction in organic chemistry that required the use of a catalyst in 1811 and published his findings the following year. In 1835, a Swedish chemist named Jöns Jakob Berzelius coined the term “catalysis” to describe reactions that were accelerated by the presence of certain substances. In addition, the substances remained unchanged as a result of the reaction.

Examples of Catalysts of Different Types 

There are many different types of catalysts that can be used in a chemical reaction, depending on the need or requirement of the reaction. Since a catalyst is used to speed up a particular reaction in an equilibrium, therefore the following are some examples:

Catalysts for the Positive

Positive catalysts are catalysts that speed up the rate at which a chemical reaction occurs. It accelerates the rate of reaction by lowering the activation energy barriers, allowing a greater number of reaction molecules to be converted into products, thereby increasing the percentage of product yield. An example of a positive catalyst: If you use the Haber’s process to make ammonia, iron oxide acts as a positive catalyst, increasing the yield of ammonia even though there is less reaction of nitrogen with the nitrogen.

Catalysts with a Negative Effect

Catalysts that slow down a reaction are called negative catalysts. As the activation energy barrier increases, the number of reactant molecules that can be converted to products decreases, and as a result, the reaction rate slows down and eventually stops. To illustrate a negative catalyst, consider the following: When acetanilide is used, the decomposition of hydrogen peroxide to water and oxygen is retarded. Acetanilide acts as a negative catalyst, slowing the rate at which hydrogen peroxide breaks down into water and oxygen. 

Conclusion

In a catalysed process, the catalyst is usually chemically reacted with the reagents, but finally regenerates, so the catalyst level remains constant. Since the catalyst is not consumed, each catalyst molecule can cause the conversion of a large number of reactant molecules. The number of molecules that have changed every minute from a single active catalyst molecule can be up to several million

faq

Frequently asked questions

Get answers to the most common queries related to the CBSE Class 11 Examination Preparation.

What is the mechanism by which a positive catalyst can alter a reaction?

Ans. A positive catalyst’s primary function is to increase the rate of reaction at the outset of the reaction ...Read full

When it comes to the Rosenmund reaction, what is the function of the catalyst poison?

Ans. The Rosenmund reaction, in which acid halides are reduced with hydrogen gas in the presence of palladium, resul...Read full

When it comes to heterogeneous catalysis, what are the important factors to consider?

Ans. Heterogeneous catalysis occurs when the reacting agent and the catalyst are in different states of matter at th...Read full

Which role do promoters play in Haber's decision-making process?

Ans. Promoters and accelerators are substances that increase the activity of a catalyst in a process. Ammonia is for...Read full

What is the significance of autocatalysis in the biological world?

Ans. Auto catalysis, also known as self-catalysis, is a process in which one of the products formed acts as a cataly...Read full

Ans. A positive catalyst’s primary function is to increase the rate of reaction at the outset of the reaction by altering the path of the reaction and thereby decreasing the activation energy basis. This results in a significant number of reactant molecules being converted into products.

Ans. The Rosenmund reaction, in which acid halides are reduced with hydrogen gas in the presence of palladium, results in the formation of aldehyde. If the catalyst is not poisoned, the reaction will not stop at the aldehyde level, which is the result of the reduction of alcohol to aldehyde. In order to reach the aldehyde concentration, Palladium has been poisoned with barium sulphate to cause it to corrode.

Ans. Heterogeneous catalysis occurs when the reacting agent and the catalyst are in different states of matter at the same time. Adsorption of reactant molecules and activation of the Catalyst  simultaneously  are the two most important steps in this process.

Ans. Promoters and accelerators are substances that increase the activity of a catalyst in a process. Ammonia is formed by the reaction of nitrogen with hydrogen in Haber’s process. Nitrogen is a very reactive element with a low yield of ammonia; therefore, in order to increase the percentage yield of ammonia formed,Iron (fe) is used as a Catalyst and  molybdenum is used as a promoter in the reaction.

Ans. Auto catalysis, also known as self-catalysis, is a process in which one of the products formed acts as a catalyst, increasing the rate of the reaction.

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