Question

Which statement best describes the reaction pathway graph for an exothermic reaction but not an endothermic reaction? It has a hill in the middle that is the highest point. It has a valley in the middle that is its lowest point. The reactants are higher in energy than the products. The products are higher in energy than the reactants.

Answer 1

Answer:  The reactants are higher in energy than the products

Explanation:

Every reaction needs a certain minimum energy to get converted to products called as activation energy. It is represented by a hill in the middle that is the highest point.

Exothermic reactions are defined as the reactions in which energy of the product is lesser than the energy of the reactants. The total energy is released in the form of heat and $\Delta H$ for the reaction comes out to be negative.

Endothermic reactions are defined as the reactions in which energy of the product is greater than the energy of the reactants. The total energy is absorbed in the form of heat and $\Delta H$ for the reaction comes out to be positive.

Answer 2

Answer: "The reactants are higher in energy than the products"

Explanation:

The exothermic reactions are characterized by the release of heat to the surroundings. The reactants lose heat that is delivered to the surroundings which implies that the products will be lower in energy than the reactants.

The hills that you can see in a reaction energy diagram are not related with the final change of energy. The hills are an indication of the activation energy needed to start the reaction, but they do not measure the change of energy from the products to the reactants.

The enthalpy that is a state variable that identifies the content of heat. Then the change of enthalpy for the exothermic reactions is negative, meaning that the energy of the products is lower than the energy of the reactants.