The diagram of chemical energy shows the amount of potential energy consumed and released during a reaction. It is important to know that the resultant products of an endothermic reaction have more energy than their reactants. In an exothermic reaction, on the other hand, the energy of the resultant products is lower than those of the reactants. As the energy from the environment is absorbed, the potential energy increases, and it decreases as it is released. In each case, the highest point of the curve represents the activation energy of the reaction.
Activation energy
A diagram of chemical activation energy shows how the energy required to achieve the transition state is provided to molecules in a reaction. It is independent of temperature and the presence of a catalyst, which can decrease this energy. The kinetic energy of the reactants is converted to the activation energy to carry out the reaction. The energy required to achieve the transition state is measured in joules per mole. Once a molecule reaches the transition state, it will move on to the next step.
In endothermic reactions, the energy of the products is greater than the energy of the reactants. In exothermic reactions, the products will be lower in energy. In this situation, the enthalpy change is negative. The height of the hill between the reactants and the products is the activation energy. The energy of the transition state is the minimum amount required for the reaction to occur. In both cases, energy is supplied to the reaction by the reacted substances.
Transition states
One of the fundamental concepts in a chemical energy diagram is the concept of transition states. In a reaction, molecules in the same phase will go through a specific chemical change. The products produced from this reaction are referred to as the products, and the reactants will be the reactants. The energy difference between the starting material and the product is greater in the transition state. This property is known as the Gibbs free energy change, and it is represented in the energy diagram by the double dagger symbol (++).
To understand the concept of transition states in a chemical energy diagram, first understand how a reaction works. The free energy of a reaction is plotted against the reaction coordinate (E-N distance). If the reaction proceeds normally, the atoms in the reactants will repel each other, causing the free energy of the reactants to increase. As the reaction proceeds, different molecules appear and disappear along the horizontal axis, which correspond to the species represented by arrow pushing.
Activated complex
The activation complex is the structure of a chemical reaction that is less energetic than the reactants. In most cases, the transition is less than half way along the reaction coordinate and the transition state is closer to the structure of the products than the reactants. Activated complexes are not easily measured, but they can be characterized by their relative energy levels. This information helps scientists better understand the energy levels of different chemical reactions.
In a chemical reaction, the reaction pathway will be indicated by a hump. This hump indicates a transition state, known as the activated complex. This diagram also shows the potential energy of the reaction with a catalyst. This diagram will also show if the reaction is endothermic or exothermic. The energy of the reaction pathway will be represented as a relative potential energy curve, called DH.
Born-Oppenheimer approximation
The Born-Oppenheimer approximate of chemical energy can greatly simplify calculations of reactivity in reactions. Its most notable benefit is its lack of nuclear kinetic energy terms. Instead, it takes into account variations in nuclei positions. It is a fundamental mathematical tool for studying the properties of chemical reactions. Hence, it has been a foundation for the advancement of theoretical chemistry.
The Born-Oppenheimer approximate of chemical energy is a model that separates nuclear motion from electron motion. It relies on the large mass ratio of nuclei and electrons. For example, a hydrogen nucleus weighs 1836 times more than an electron. This approximation was first proposed by Robert Oppenheimer and Max Born in 1927.
Examples
A chemical energy diagram shows how the reactions in a system change as the amount of energy input increases. The energy of reactants rises as the reaction progresses, while the energy of products decreases. It is this process that creates products, and the energy of these products is represented as a vertical axis. During a chemical reaction, energy is released to form new bonds. The energy level of a chemical reaction is represented by a large slope that goes down from the reactants to the products.
A chemical energy diagram is a simplified representation of a chemical reaction, and it shows how energy changes as the reactants and products undergo a reaction. It’s important to understand that many chemical reactions release energy as heat, like burning fuel. Other chemical reactions, however, require a constant supply of heat, such as the splitting of calcium carbonate into calcium oxide and carbon dioxide. In both cases, the energy change in the two species is referred to as activation energy.