How do reaction pathway diagrams illustrate energy changes?

Reaction pathway diagrams illustrate energy changes by showing the energy levels of reactants and products along with the activation energy.

In more detail, a reaction pathway diagram, also known as an energy profile diagram, is a graphical representation of the energy changes that occur during a chemical reaction. It provides a visual way to understand the energy transformations that take place during a reaction. The diagram typically has energy on the vertical axis and the progress of the reaction on the horizontal axis.

At the start of the reaction, the energy level corresponds to the energy of the reactants. As the reaction progresses, the energy level may rise to a peak, representing the activation energy. This is the minimum energy required for the reaction to occur. The peak is followed by a drop to the energy level of the products. If the energy level of the products is lower than that of the reactants, the reaction is exothermic, meaning it releases energy. If the energy level of the products is higher, the reaction is endothermic, meaning it absorbs energy.

The diagram can also show intermediate stages in a reaction, represented by smaller peaks and troughs. These correspond to the energy levels of intermediate compounds formed during the reaction.

In summary, reaction pathway diagrams are a useful tool for visualising the energy changes in a chemical reaction. They show the energy of the reactants, the activation energy, the energy of the products, and any intermediate energy levels. By analysing these diagrams, students can gain a deeper understanding of the energy transformations that occur during chemical reactions.