Why does an increase in the temperature increase the rate of a reaction?
A. reactant particles' speed is increased, so there are more collisions
B. reactant particles' speed is decreased, so molecules collide with less force
C. more molecules means more possible collisions
D. more molecules means better orientations for collisions
A. reactant particles' speed is increased, so there are more collisions.
The correct answer is A. Reactant particles' speed is increased, so there are more collisions.
When the temperature of a reaction increases, the average kinetic energy of the reactant particles also increases. This means that the particles move faster and have more energy. As a result, they collide with each other more frequently. Since the rate of a chemical reaction is determined by the frequency of successful collisions between reactant particles, an increase in temperature leads to an increase in the rate of the reaction.
Option B, stating that an increase in temperature decreases the speed of reactant particles, is incorrect. Higher temperatures actually cause particles to move faster.
Option C, stating that more molecules means more possible collisions, is not the main reason behind the increase in reaction rate with temperature. While it is true that an increase in the number of reactant molecules can lead to an increase in collisions, the main factor affected by temperature is the speed of the particles.
Option D, suggesting that more molecules means better orientations for collisions, is not the primary reason for the increase in reaction rate with temperature. Although proper molecular orientation is important for a successful reaction, an increase in temperature primarily affects the speed of the particles rather than their orientation.