Factors Affecting Rate of a Chemical Reaction-Nature of the Reactant, Concentration of the Reactants, Temperature of the Reactants, Presence of a Catalyst, Pressure factor

What is Reaction Rate?

The rate of reaction, often known as the reaction rate, refers to the pace at which reactants are converted into products. When we talk about chemical processes, we know that the rate at which they occur varies greatly. 

Some chemical reactions are virtually instantaneous, while others take time to achieve their final equilibrium. The rate of a reaction, according to the general definition, is the rate at which a reaction occurs. 

Wood combustion, for example, has a high reaction rate because the process is fast, whereas iron rusting has a low reaction rate since the process is sluggish.

Factors Affecting the Rate of Reaction

Chemical reactions occur only when reactant molecules clash with one another. The Collision hypothesis of Chemical Kinetics describes this. According to the collision, for a reaction to occur, the reactants must collide with sufficient energy that is greater than the activation energy Ea. However, other factors can affect the rate of reaction, such as increasing the fraction of molecules with energies greater than the activation energy Ea. The rate of a reaction is influenced by four elements. They are as follows:

Nature of the Reactant

Chemical reactions occur almost instantly in an aqueous solution. Because the chemical bonds of reactant molecules are broken down. The ions’ attractive forces are disrupted, and the ions are hydrated by the water molecules. Furthermore, most ions have equal attractive forces in all directions. In most circumstances, no covalent connections must be disrupted in these situations. Reactions between molecules that require covalent bonds to be broken, on the other hand, tend to be very sluggish. As a result, the pace of reaction is influenced by the structural properties of the reactant molecules, such as bond polarity, geometry, overall size, and orientation.

Concentration of the Reactants

We know that the rate of most reactions increases as the concentration of the reactants increases. Increasing a reactant’s concentration means increasing the number of reactant molecules in the same volume. For many (but not all) reactions, there is a direct link between concentration and rate of reaction. As a result, when the concentration doubles, the rate of reaction doubles as well. This is explained by the collision hypothesis, which states that doubling the number of reactant molecules results in twice as many collisions occurring at the same time.

Temperature of the Reactants

In almost all circumstances, the rate of a reaction increases as the temperature rises. The pace of reaction doubles per 10° increase in temperature! This is a really strong effect. For example, a temperature increase from 20° to 80° (six 10° increments) will result in a reaction rate that is 26 = 64 times faster. That is a significant rate change. The Collision theory can also explain this: the average kinetic energy of all molecules is a direct function of temperature. Because the molecules collide with more energy, their activation energy lowers.

Presence of a Catalyst

A catalyst is a chemical that speeds up a reaction without really participating in it. Catalysts work by giving an alternative chemical pathway. It is the one that uses the least amount of energy to transform the reactants into products. Some catalysts accelerate more than one sort of reaction, but others, such as enzymes in our cells, are specific to a particular reaction or even a single type of reactant molecule. As a result, a catalyst accelerates the process.

Pressure factor

The concentration of gases increases as pressure increases, increasing the rate of reaction. The reaction rate accelerates in the direction of fewer gaseous molecules and slows in the opposite direction. As a result, it is clear that pressure and concentration are related and that they both influence the rate of response.

Sample Questions (FAQs)

Question 1: How does concentration affect the rate of reaction?

Answer: 

Collision theory states that increasing the number of reactant molecules increases the number of collisions that occur for a reaction to occur. Similarly, raising the concentration, or the amount of reactant molecules in the solution, will increase the number of collisions that occur in the solution. As a result, the rate of the reaction will accelerate.

Question 2: What is the difference between the chemical kinetics of the reaction and the chemical balancing of the equation?

Answer:

The chemical kinetics of the reaction provides information on the mechanism and pace of the reaction, whereas a balanced chemical equation provides information about the stoichiometry of the reaction.

Question 3: Why does the reaction rate increase with increasing temperature?

Answer:

As the temperature of the reaction rises, the average kinetic energy of the ions and molecules rises as collisions between the ions and molecules become more frequent.

Question 4: What is the difference between chemical thermodynamics and chemical kinetics?

Answer: 

Chemical kinetics, often known as reaction kinetics, is concerned with the investigation of reaction rates. Chemical thermodynamics is the study of the interaction of heat and work with chemical processes or physical state changes within the limitations of thermodynamic rules.

Question 5: How do Catalysts speed up reactions?

Answer: 

The catalyst speeds up the reaction by allowing a novel reaction pathway to occur at a lower activation energy. It does not consume in the process and also does not alter in chemical properties.

Er. Neeraj K.Anand is a freelance mentor and writer who specializes in Engineering & Science subjects. Neeraj Anand received a B.Tech degree in Electronics and Communication Engineering from N.I.T Warangal & M.Tech Post Graduation from IETE, New Delhi. He has over 30 years of teaching experience and serves as the Head of Department of ANAND CLASSES. He concentrated all his energy and experiences in academics and subsequently grew up as one of the best mentors in the country for students aspiring for success in competitive examinations. In parallel, he started a Technical Publication "ANAND TECHNICAL PUBLISHERS" in 2002 and Educational Newspaper "NATIONAL EDUCATION NEWS" in 2014 at Jalandhar. Now he is a Director of leading publication "ANAND TECHNICAL PUBLISHERS", "ANAND CLASSES" and "NATIONAL EDUCATION NEWS". He has published more than hundred books in the field of Physics, Mathematics, Computers and Information Technology. Besides this he has written many books to help students prepare for IIT-JEE and AIPMT entrance exams. He is an executive member of the IEEE (Institute of Electrical & Electronics Engineers. USA) and honorary member of many Indian scientific societies such as Institution of Electronics & Telecommunication Engineers, Aeronautical Society of India, Bioinformatics Institute of India, Institution of Engineers. He has got award from American Biographical Institute Board of International Research in the year 2005.