Keq = Dynamic Equilibrium—Rate of forward reaction equals rate of reverse
reaction; constant but not equal concentration of products and reactants.Keq > 1 forward reaction favored (concentration of products greater than
reactants)Keq < 1 reverse reaction favored (concentration of reactants greater than
products)Phase Change Equilibrium
The principle of equilibrium does not only apply to chemical reactions but also
to any system in which one thing is transforming, reversibly, into another—such
as a phase change, for instance. Remember vapor pressure? Suppose water is in
a sealed container, at a temperature below water’s boiling point; some molecules
will still gather enough kinetic energy to escape from the liquid and become gas.
Then they will lose their kinetic energy—they will cool down and fall back into
the container as water. Other liquid molecules gain enough kinetic energy to
escape into the gas phase, and the process continues. Some liquid is converted to
gas, and some gas is converted to liquid. The process is in equilibrium.
Thing or Things?
The principle of equilibrium
would also hold true
if more than one thing in a
system were being reversibly