KINETICS
The rate at which reactants are converted into products in a reaction is called the
reaction rate. Remember that chemical reactions involve breaking old bonds (in
the reactants) and making new bonds (in products). In order for bond breaking
and bond making to occur, reactant molecules (or atoms or ions) must collide
with sufficient energy and proper orientation. Why are energy and orientation
important? Well, the reactant molecules need to collide with enough kinetic
energy to break their bonds, and they need to collide with the proper orientation
for new bonds to form. Consider the gas phase reaction.
H 2 (g) + I 2 (g) → 2HI(g)Notice that if an H 2 and I 2 molecule collide with enough kinetic energy and in
the orientation shown below, the atoms are in an ideal position to form new H–I
bonds.
First: Reactant molecules H 2 and I 2 move toward each other with sufficient
energy.