Which definition best describes the term activation energy?
A the energy a compound possesses by virtue of its chemical bonds and their orientation
B the energy required to separate the ions in a crystalline solid
C the energy required to remove an electron from a gaseous atom
D the minimum net kinetic energy that colliding particles must possess in order to react
E the amount of energy absorbed or released when a chemical reaction takes place
The correct answer and explanation is :
The correct answer is:
D: The minimum net kinetic energy that colliding particles must possess in order to react.
Explanation:
Activation energy ((E_a)) is a fundamental concept in chemical kinetics that describes the minimum amount of energy required for a chemical reaction to occur. It represents the energy barrier that reactant molecules must overcome to be transformed into products.
Understanding Activation Energy
Chemical reactions occur when reactant molecules collide with sufficient energy and proper orientation to break existing bonds and form new ones. However, not all collisions lead to a reaction. Only those collisions where the kinetic energy of the molecules meets or exceeds the activation energy will result in a successful reaction.
Role of Activation Energy in Reactions
- Determines Reaction Rate
- A high activation energy means that fewer molecules have enough energy to react, leading to a slower reaction rate.
- A low activation energy allows more molecules to react, resulting in a faster reaction.
- Effect of Temperature
- Increasing temperature raises the kinetic energy of molecules, increasing the number of successful collisions and speeding up the reaction.
- This is explained by the Arrhenius equation:
[
k = A e^{-\frac{E_a}{RT}}
]
where ( k ) is the rate constant, ( A ) is the frequency factor, ( E_a ) is the activation energy, ( R ) is the gas constant, and ( T ) is the temperature in Kelvin.
- Catalysts and Activation Energy
- Catalysts lower activation energy by providing an alternative reaction pathway with a lower energy barrier, increasing the reaction rate.
Thus, activation energy is crucial in controlling how fast or slow a reaction proceeds.