Understanding Reaction Rates The rate of a chemical reaction measures how quickly reactants are converted into products over time. It can be calculated by monit...
The rate of a chemical reaction measures how quickly reactants are converted into products over time. It can be calculated by monitoring the change in concentration of reactants or products. Factors that affect reaction rates include:
Increasing temperature increases the average kinetic energy of particles, leading to more frequent and energetic collisions. This increases the rate of reaction.
Higher concentrations or partial pressures of reactants increase the frequency of collisions between particles, increasing the rate of reaction.
Increasing the surface area of solid reactants provides more sites for collisions to occur, increasing the reaction rate.
Catalysts lower the activation energy required for a reaction, providing an alternative pathway with a lower energy barrier. This increases the rate by allowing more particles to overcome the activation energy.
According to the collision theory, reactions occur when particles collide with sufficient energy (the activation energy) and correct orientation. The activation energy is the minimum kinetic energy particles must possess for a successful collision and reaction.
Problem: In a reaction, the concentration of a reactant decreases from 1.2 mol/dm3 to 0.4 mol/dm3 in 120 seconds. Calculate the average rate of reaction.
Solution:
Many reactions are reversible, with products being able to re-form reactants. At equilibrium, the forward and reverse reaction rates are equal. Le Chatelier's Principle states that if a system at equilibrium is disturbed, it will shift to counteract the change.
Changes in temperature, pressure, or concentration can disturb the equilibrium, causing a shift in the position of equilibrium to establish a new balance.