Introduction
It is essential to evaluate what occurs during a reaction on the molecular level to understand the kinetics of chemical reactions and the factors affecting them. Based on the collision theory of reactivity, reactions happen when reactant molecules collide effectively (Felder et al., 2020). However, for this collision to occur, the reactant molecules must be aligned in space correctly to allow bond breaking, formation, and rearrangement of atoms to form product molecules. The rate of reaction can vary significantly over an extensive range of time scales, with some reactions reacting spontaneously or explosively at fast rates while others occur sluggishly. According to collision theory, a majority of factors are known to affect the rate of reaction (‘‘Factors that affect the rate of reactions – Introductory chemistry – 1st Canadian edition,’’ n.d.). Therefore, slowing down undesirable reactions or accelerating chemical processes to increase productivity can be achieved by controlling the reaction rate through a change in certain conditions of reactions.
Factors Affecting Reaction Rates
Although a balanced chemical equation for a reaction describes quantitatively the association between the amount of reactants available and products that can be formed, it does not provide any information on how fast the reaction will occur. To understand this, it is essential to study the chemical kinetics of reaction that depends on numerous factors (‘‘M13Q1: Introduction to kinetics; Concept of reaction rate – Chem 103/104 resource book,’’ n.d.). According to collision theory, the rate of a chemical reaction can be affected by four major factors. These factors include reactant concentration, the physical state of the reactants and surface area, temperature, and the presence of a catalyst.
Reactant Concentration
Two substances cannot react with one another unless their constituent particles come into contact. Without contact, the reaction rate of substances is zero. The more reactant particles collide per unit of time, the more the reaction occurs. Accordingly, increasing the reactant concentration increases the reaction rate because it leads to more collisions.
Physical State of the Reactants and Surface Area
The reaction of heterogenous mixtures or reactants in different phases, like solid and liquid reactants, occurs only at the interface amid the two phases. Dividing materials into many pieces increases surface area and rate of reaction. Therefore, increasing the rate of reaction of heterogenous mixtures can be done by stirring or pounding the material into many smaller pieces, which increases the contact surface area.
Temperature
When the temperature of a system increases, it raises the average kinetic energy of its constituent particles. The rise in kinetic energy makes the particles move faster and collide more often per unit of time, thereby increasing the reaction rate. An increase in temperature results in a more significant proportion of molecules with the minimum energy required for an effective collision. Therefore, nearly for all chemical reactions, the rate increases with increasing temperature and decreases with decreasing temperature.
Presence of a Catalyst
A catalyst refers to a substance that speeds up the rate of reaction. Catalyst participates in chemical reactions without being consumed and offers an alternative reaction pathway to get products. Catalysts are critical to many biochemical reactions; therefore, including catalysts will affect the reaction rate. The type of catalyst involved in a chemical reaction depends on the type of reaction and reactants involved.
Conclusion
In conclusion, collision theory envisages the rates of chemical reactions based on the assumption that in order for the reaction to happen it is a must for the reacting molecules or atoms to collide with each other. However, it is depicted that chemical reaction is influenced by four major factors including reactant concentration, the physical state of the reactants and surface area, temperature, and the presence of a catalyst. Changing certain conditions can also accelerate or slow down the rate of chemical reactions.
References
Factors that affect the rate of reactions – Introductory chemistry – 1st Canadian edition. (n.d.). BCcampus Open Publishing – Open Textbooks Adapted and Created by BC Faculty. Web.
Felder, R. M., Rousseau, R. W., & Bullard, L. G. (2020). Elementary principles of chemical processes. John Wiley & Sons.
M13Q1: Introduction to kinetics; Concept of reaction rate – Chem 103/104 resource book. (n.d.). University of Wisconsin Pressbooks – Publishing Open Texts at UW-Madison. Web.