Factors Affecting Rate of a Chemical Reaction

The rate of reaction is the pace at which the products of a chemical reaction are created from the reactants. It provides some information about the time frame in which a reaction can be accomplished. For example, the reaction rate of cellulose combustion in fire is extremely high, and the reaction is finished in less than a second.

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 E_a. However, other factors can affect the rate of reaction, such as increasing the fraction of molecules with energies greater than the activation energy E_a. 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

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.