What is chemical kinetics?

IGCSE Chemistry requires students to understand the foundations of this scientific discipline, and arguably, chemical kinetics forms one of the most essential aspects of Chemistry.

Chemical kinetics refers to the study of the rate of a chemical reaction. In Chemistry, the rate of a reaction is determined by how fast reactants are converted into products. This can either be calculated by recording the amount of product formed over a period of time, or by measuring the amount of reactant used up over time. At the start of the reaction, there is a high proportion of reactants, therefore the rate of reaction will be at its highest. As the reactants are converted into products, the concentration of reactants decreases, and the rate of reaction also decreases accordingly, until there are no more reactants left. Chemical kinetics are an important part of the IGCSE Chemistry syllabus, and it’s a topic with which learners often need assistance.

Collision theory at IGCSE

IGCSE Chemistry requires students to learn subject-specific terminology, which allows those taking IGCSE Chemistry to respond in a scientifically-appropriate manner.

For example, reaction rates can be explained scientifically by the “Collision Theory”. Reactions take place when particles collide in the correct orientation and with sufficient energy. The minimum amount of energy for a collision to be successful is known as the activation energy, and the rate of reaction depends on the rate of successful collisions between the reactant particles. This is what has become known as Collision Theory. Those studying IGCSE Chemistry should be aware that the more successful collisions there are, the faster the rate of reaction. However, it gets trickier when IGCSE Chemistry students take into account that the number of successful collisions depends on 5 different factors, all of which must be memorised.

Factors affecting rate of reaction: what IGCSE students need to know

The 5 factors affecting the rate of reaction are:

Temperature
Concentration
Pressure
Surface area
Catalyst

Temperature: If the temperature of a chemical reaction is increased, the reactant particles will have more kinetic energy. This means that the particles will move more quickly, leading to particles colliding more often, resulting in more frequent successful collisions and the rate of reaction increases.

Concentration and Pressure: If the concentration or pressure is increased, there are more reactant particles in a given volume. This means there is a greater chance of the particles colliding, leading to more successful collisions per second. Thus the rate of reaction increases.

Surface Area: The rate of reaction can be increased by increasing the area of a solid reactant, this can be done by cutting the substance into small pieces or by grinding it into a powder. Large pieces mean there is a small surface area, whereas smaller pieces or a powder results in a large surface area. If the surface area is increased, there are more particles exposed to the other reactant, and once again increasing the chance of particles colliding successfully.

Catalyst: A catalyst speeds up the rate of reaction. This is because the catalyst provides an alternate reaction pathway with a lower activation energy so less energy is required for a successful collision. A catalyst is chemically unchanged at the end of the reaction so can be reused.

Supporting IGCSE Chemistry to know

While chemical kinetics is an important topic in IGCSE Chemistry, it is only one among many. The challenge of the IGCSEs lies in the sheer breadth of material that young learners must learn in order to score high marks on their examinations. At BartyED, we understand that this will be most IGCSE students’ first set of ‘real’ examinations, and we are here to support them through this challenge.

If you or your child would like further support in IGCSE Chemistry, or any other IGCSE subject, don’t hesitate to reach out via phone (2882 1017) or email (enquiries@bartyed.com) today to find out more about how BartyED can help you achieve your goals in your examinations.