Which concept explains why the rate of a chemical reaction increases with temperature?

Which concept explains why the rate of a chemical reaction increases with temperature?

• A. Arrhenius principle (temperature dependence of reaction rate)
• B. Le Châtelier's principle
• C. Boyle's law
• D. First law of thermodynamics

Answer: (A)

Raising temperature speeds up a reaction because it increases how energetically the molecules move. With higher temperature, more molecules have enough energy to overcome the activation energy barrier needed for the reaction to happen. The distribution of molecular energies (Boltzmann distribution) shifts so a larger fraction of collisions are energetic enough, and, combined with more frequent collisions, the overall rate goes up. This behavior is captured by the Arrhenius relationship, where the rate constant grows as temperature increases (k = A e^{-Ea/RT}). Here, A reflects how often molecules collide with the right orientation, and the exponential term reflects the fraction of collisions that have enough energy. So temperature directly influences both collision energy and the number of effective collisions, driving up the reaction rate. Le Châtelier's principle concerns how equilibria respond to stress, not the speed of a reaction. Boyle's law is about how pressure and volume relate for gases, and the first law of thermodynamics is about energy conservation in processes. They explain other aspects of chemistry, but not why temperature accelerates reaction rates.

Raising temperature speeds up a reaction because it increases how energetically the molecules move. With higher temperature, more molecules have enough energy to overcome the activation energy barrier needed for the reaction to happen. The distribution of molecular energies (Boltzmann distribution) shifts so a larger fraction of collisions are energetic enough, and, combined with more frequent collisions, the overall rate goes up. This behavior is captured by the Arrhenius relationship, where the rate constant grows as temperature increases (k = A e^{-Ea/RT}). Here, A reflects how often molecules collide with the right orientation, and the exponential term reflects the fraction of collisions that have enough energy. So temperature directly influences both collision energy and the number of effective collisions, driving up the reaction rate.

Le Châtelier's principle concerns how equilibria respond to stress, not the speed of a reaction. Boyle's law is about how pressure and volume relate for gases, and the first law of thermodynamics is about energy conservation in processes. They explain other aspects of chemistry, but not why temperature accelerates reaction rates.