Which of the following statements is NOT true regarding exothermic and endothermic processes?

Which of the following statements is NOT true regarding exothermic and endothermic processes?

• A. The change in enthalpy is positive for an exothermic reaction.
• B. Exothermic reactions release heat.
• C. Endothermic reactions absorb heat.
• D. Chemical bonds break in endothermic reactions.

Answer: (A)

The statement that the change in enthalpy is positive for an exothermic reaction is not true. In an exothermic reaction, the system releases energy in the form of heat to its surroundings, leading to a decrease in the internal energy of the system. This results in a negative change in enthalpy (ΔH), reflecting the fact that the products have lower energy than the reactants. In contrast, during an endothermic reaction, energy is absorbed from the surroundings, causing an increase in the internal energy of the system; thus, the change in enthalpy is positive. This distinction is critical for understanding the thermodynamics of chemical reactions and how they interact with their environment. Other statements correctly describe the characteristics of exothermic and endothermic processes, illustrating the accurate associations of energy flow in chemical reactions.

The statement that the change in enthalpy is positive for an exothermic reaction is not true. In an exothermic reaction, the system releases energy in the form of heat to its surroundings, leading to a decrease in the internal energy of the system. This results in a negative change in enthalpy (ΔH), reflecting the fact that the products have lower energy than the reactants.

In contrast, during an endothermic reaction, energy is absorbed from the surroundings, causing an increase in the internal energy of the system; thus, the change in enthalpy is positive. This distinction is critical for understanding the thermodynamics of chemical reactions and how they interact with their environment.

Other statements correctly describe the characteristics of exothermic and endothermic processes, illustrating the accurate associations of energy flow in chemical reactions.