When every collision between reactants leads to a reaction, what determines the rate at which the reaction occurs?
The correct answer and explanation is :
The rate at which a reaction occurs, even when every collision between reactants leads to a reaction, is determined by the frequency of collisions and the activation energy.
Explanation:
- Collision Frequency: The more often reactant molecules collide, the higher the reaction rate. The rate of reaction is directly proportional to the number of collisions between molecules. In a given system, factors such as temperature, concentration, and pressure can influence the collision frequency. For example, increasing the temperature generally leads to more energetic collisions, while increasing the concentration of reactants increases the likelihood of molecules colliding with each other.
- Activation Energy (Ea): Even if every collision between reactant molecules results in a reaction, not all collisions will lead to a successful reaction unless the molecules have enough energy. This is where activation energy comes into play. Activation energy is the minimum energy required for a chemical reaction to occur. In other words, even though the reactants may collide, only those with enough energy (greater than or equal to the activation energy) will overcome the energy barrier to form products.
Thus, even when every collision results in a reaction (ideal case), the rate is still influenced by the number of collisions that occur with sufficient energy to overcome the activation energy barrier.
- Temperature: Higher temperatures provide more kinetic energy to the molecules, making it more likely that collisions will have enough energy to surpass the activation energy.
- Concentration/Pressure: Higher concentrations of reactants or increased pressure (for gases) increase the number of collisions, thereby increasing the reaction rate.
In summary, the rate of reaction is determined by the frequency of successful collisions (which can be influenced by temperature, concentration, and pressure) and the energy of the collisions (which is governed by the activation energy). Even with every collision being productive, the rate is still dependent on these factors.