Understanding Reaction Rates
Reaction rate measures how quickly reactants turn into products, expressed in molarity per second M/s. For a reaction where substance A becomes substance B, we calculate the rate as: rate = -ΔA/Δt = kA. Those square brackets indicate concentration in molarity.
According to collision theory, reactions happen when particles collide with sufficient energy and proper orientation. Not all collisions lead to reactions - particles need to overcome the activation energy (Ea), which is the minimum energy required for a reaction to occur. During this process, molecules briefly form an unstable activated complex at the peak of the energy barrier.
Several factors affect reaction rates. Higher concentrations create more frequent collisions, increasing reaction rates. Similarly, increased pressure, greater surface area, and higher temperatures all boost reaction rates by creating more successful collisions between particles.
💡 Catalysts are reaction superheroes! They speed up reactions by lowering the activation energy without being consumed in the process. This is why enzymes (biological catalysts) are so important in your body - they make essential reactions happen fast enough to sustain life.
The specific rate constant (k) relates reaction rate to reactant concentrations and must be determined experimentally for each reaction under specific conditions.