At equilibrium
[HI] = (2.00 − x) mol/L(For every mole of HI that decomposes, only 0.5 mole of H 2 and 0.5 mole of I 2
are formed.)
Solving for x gives:
x = 0.456Then, substituting into the equilibrium conditions,
TIP
Know Le Châtelier’s Principle.LE CHÂTELIER’S PRINCIPLE
A general law, Le Châtelier’s Principle, can be used to explain the results of
applying any change of condition (stress) on a system in equilibrium. It states
that if a stress is placed upon a system in equilibrium, the equilibrium is
displaced in the direction that counteracts the effect of the stress. An increase
in concentration of a substance favors the reaction that uses up that substance and
lowers its concentration. A rise in temperature favors the reaction that absorbs
heat and so tends to lower the temperature. These ideas are further developed
below.