Propane reacts with oxygen to produce carbon dioxide and water.
The reaction is exothermic.
Figure 8 shows four reaction profiles.
Which is the correct reaction profile and labels for the reaction between propane and oxygen?

A reaction profile diagram shows the energy of the system as the reaction progresses. - **Exothermic Reaction:** An exothermic reaction releases energy into the surroundings. This means the products have lower potential energy than the reactants. On the profile, the energy level at the end of the reaction must be lower than the energy level at the start. This eliminates profiles A and D, which show endothermic reactions. - **Labels:** We are left with B and C. Both show an exothermic profile. We need to check the label for "Overall energy change". - The **overall energy change (ΔH)** is the difference between the energy of the products and the energy of the reactants. - The **activation energy (Ea)** is the minimum energy required to start the reaction, represented by the height of the "hump" from the reactant level. - In profile **B**, the label correctly points to the difference between the reactant and product energy levels. - In profile **C**, the label is pointing to the activation energy, which is incorrect. Therefore, profile B is the correct representation.