Chapter 12 Laboratory: Chemical Kinetics 211

Chemical kinetics, also called reaction kinetics, is the study of reaction rates in chemical

reactions. In simple terms, if two reactant molecules are to interact with each other, they

must collide with sufficient energy to initiate the reaction. Two molecules that do not

collide cannot react, regardless of how high their energies are. Conversely, two molecules

that do collide, but with insufficient energy, cannot react.

Intuitively, it’s easy to understand that several factors affect reaction rates. Temperature

affects reaction rates because molecules at a higher temperature have higher energies,

and therefore any particular collision between reactant molecules is more likely to have

the energy needed to initiate the reaction. Concentration affects reaction rates, because

the number of reactant molecules is higher in more concentrated solutions, and therefore

collisions between reactant molecules are more likely to occur. When one or more of the

reactants is a gas, pressure affects reaction rates, because gases at higher pressures

contain more molecules in a given volume (in effect, their concentration is higher). Finally,

when one or more of the reactants is a solid, surface area affects reaction rates, because

a larger surface area exposes more of the reactant molecules to collisions with the other

reactant or reactants.

In this chapter, we’ll examine the effects of temperature, concentration, and surface area

on reaction rates.

Laboratory: 12

Chemical Kinetics