Have you ever wondered whether adding more water to a chemical mixture would make it react faster? It is a common question among students and amateur chemists alike. That said, the relationship between concentration and reaction speed is far more nuanced than a simple yes or no answer. Also, the short answer is generally no; diluting a solution typically decreases the rate of reaction. To fully understand why dilution usually slows down chemical processes, we have to look at the fundamental principles of reaction kinetics, specifically collision theory and reaction mechanisms It's one of those things that adds up..
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The Science Behind the Speed: Collision Theory
To understand why diluting a solution decreases the rate of reaction, we must first understand collision theory. And according to this theory, for a chemical reaction to occur, reactant molecules must collide with sufficient energy (known as the activation energy) and proper orientation. The frequency at which these successful collisions happen dictates the overall speed of the reaction And it works..
When you dilute a solution—meaning you add more solvent, usually water, to reduce the concentration of the solutes—you are effectively spreading the same number of reactant particles out over a larger volume. This has a direct and predictable impact on collision
