Chemistry I Honors Kinetics

What is Kinetics? This is a totally different study than anything we have done. Some of it uses concepts from Unit 1, but the main focus of the topic is new. Kinetics is the study of the rate of a reaction. There is no worry as to whether the reaction will occur – it is assumed that a reaction does happen. Instead, we focus on how fast the reactants are consumed.

From Unit #1 Exothermic ReactionEndothermic Reaction

The Boltzman Distribution

Kinetics Factor #1 Part of the study of Kinetics will focus on variables that change the rate at which the reaction occurs. The most common variable is the temperature. Remember that the velocity and energy of the particles in a system changes directly with the temperature. As the temperature increases, the energy of the particles increases. Question is – what does this do to the Boltzman distribution?

Changing the Temperature

Kinetics Factor #2 The 2 nd factor considered is the presence of a catalyst. We learned in Unit 1 that a catalyst speeds up a reaction. The graph on the right shows what a catalyst does to the exothermic graph.

Catalyst and the Boltzman Distribution

Kinetics Factor #3 The final kinetics factor is the concentration of the reactant particles. Think of this simply as the number of available molecules to react.

Consider Dodgeball

Dodgeball Kinetics At the beginning of the game, there are lots of reactant “people” and the rate at which they are eliminated (reacted) is high. High concentration of reactant particles results in higher rate of reaction. But as the number of reactant “people” decreases, there are fewer collisions – the rate of reaction goes down. Lower concentration of reactant particles results in lower rate of reaction.