Final answer:
A substance is more likely to react at higher temperatures because the increased kinetic energy of its particles leads to more frequent and energetic collisions, which are more likely to surpass the required activation energy for a reaction to occur.
Step-by-step explanation:
A substance in a system is more likely to react when the temperature is higher due to various reasons explained by kinetic-molecular theory. As the temperature increases, so does the average kinetic energy of the substance's particles. This results in the particles moving faster, leading to more frequent and forceful collisions. These more energetic collisions can more effectively surmount the activation energy barrier, which is the energy required for a reaction to proceed. The higher number of such effective collisions increases the rate at which reactants transform into products, hence making substances more reactive at higher temperatures.
Effect of Temperature on Reaction Rates
Raising the temperature of a reaction increases not only the number of collisions among reactant particles but also the energy of these collisions. Therefore, a temperature rise broadens the distribution of kinetic energies and increases the frequency of particles gaining enough energy to overcome the activation energy. This enhancement in collision energy and frequency speeds up the reaction rate, often substantially. For many chemical processes, reaction rates approximately double for every 10 °C increase in temperature.