Which definition best describes the term activation energy?
A. The energy of motion
B. The energy required to separate ions in a crystalline solid
C. The energy required to remove an electron from a gaseous atom
D. The minimum net energy that colliding particles must possess in order to react
The Correct Answer and Explanation is:
Correct Answer: D. The minimum net energy that colliding particles must possess in order to react
Explanation:
Activation energy is a fundamental concept in chemistry and reaction kinetics. It refers to the minimum amount of energy that reacting particles (atoms or molecules) must have during a collision for a chemical reaction to occur.
Think of activation energy like a hill that reactants must climb over to transform into products. If they don’t have enough energy to reach the top of this “hill,” they will bounce off each other without reacting. But if their energy is equal to or greater than the activation energy, the particles can overcome the energy barrier and form new bonds—leading to a chemical reaction.
This concept is crucial for understanding why some reactions happen quickly, while others happen slowly or require external factors like heat or catalysts. For example:
- Heating a substance increases the kinetic energy of its particles, helping more of them reach the activation energy.
- Catalysts lower the activation energy, making it easier for the reaction to occur.
Let’s briefly look at the other choices to understand why they are incorrect:
- A. The energy of motion refers to kinetic energy, not activation energy.
- B. The energy required to separate ions in a crystalline solid describes lattice energy, important in ionic compounds, not chemical reaction initiation.
- C. The energy required to remove an electron from a gaseous atom is the ionization energy, which relates to the formation of ions, not the start of chemical reactions.
In summary, activation energy (Choice D) is the energy “threshold” reactants must meet to start a chemical reaction. It plays a central role in reaction rates and is influenced by temperature, concentration, and catalysts.
