Chapter 14

The following reaction in aqueous solution has \(K_{\mathrm{c}}=\) \(1 \times 10^{-85}\) at a temperature of \(25^{\circ} \mathrm{C}\). \(7 \mathrm{IO}_{3}^{-}(a q)+9 \mathrm{H}_{2} \mathrm{O}+7 \mathrm{H}^{+}(a q) \rightleftharpoons \mathrm{I}_{2}(a q)+5 \mathrm{H}_{5} \mathrm{IO}_{6}(a q)\) What is the equilibrium law for this reaction?

At \(27^{\circ} \mathrm{C}, K_{\mathrm{P}}=1.5 \times 10^{18}\) for the reaction $$ 3 \mathrm{NO}(g) \rightleftharpoons \mathrm{N}_{2} \mathrm{O}(g)+\mathrm{NO}_{2}(g) $$ If \(0.030 \mathrm{~mol}\) of \(\mathrm{NO}\) were placed in a \(1.00 \mathrm{~L}\) vessel and this equilibrium were established, what would be the equilibrium concentrations of \(\mathrm{NO}, \mathrm{N}_{2} \mathrm{O},\) and \(\mathrm{NO}_{2} ?\)

Consider the equilibrium \(2 \mathrm{NaHSO}_{3}(s) \rightleftharpoons \mathrm{Na}_{2} \mathrm{SO}_{3}(s)+\mathrm{H}_{2} \mathrm{O}(g)+\mathrm{SO}_{2}(g)\) How will the position of equilibrium be affected by the following changes? (a) Adding \(\mathrm{NaHSO}_{3}\) to the reaction vessel (b) Removing \(\mathrm{Na}_{2} \mathrm{SO}_{3}\) from the reaction vessel (c) Adding \(\mathrm{H}_{2} \mathrm{O}\) to the reaction vessel (d) Increasing the volume of the reaction vessel at con- stant temperature

To study the following reaction at \(20^{\circ} \mathrm{C}\), \(\mathrm{NO}(g)+\mathrm{NO}_{2}(g)+\mathrm{H}_{2} \mathrm{O}(g) \rightleftharpoons 2 \mathrm{HNO}_{2}(g)\) a mixture of \(\mathrm{NO}(g), \mathrm{NO}_{2}(g)\), and \(\mathrm{H}_{2} \mathrm{O}(g)\) was prepared in a \(10.0 \mathrm{~L}\) glass bulb. For \(\mathrm{NO}, \mathrm{NO}_{2},\) and \(\mathrm{HNO}_{2},\) the initial concentrations were as follows: \([\mathrm{NO}]=\left[\mathrm{NO}_{2}\right]=\) \(2.59 \times 10^{-3} M\) and \(\left[\mathrm{HNO}_{2}\right]=0 M .\) The initial partial pressure of \(\mathrm{H}_{2} \mathrm{O}(g)\) was 17.5 torr. When equilibrium was reached, the \(\mathrm{HNO}_{2}\) concentration was \(4.0 \times 10^{-4} \mathrm{M}\) Calculate the equilibrium constant, \(K_{\mathrm{c}},\) for this reaction.

Why are equilibrium concentrations useful to know?

Suppose we set up a system in which water is poured into a vessel having a hole in the bottom. If the rate of water inflow is adjusted so that it matches the rate at which water drains through the hole, the amount of water in the vessel remains constant over time. Is this an equilibrium system? Explain.

Do equilibrium laws apply to other systems outside of chemistry? Give examples.

If a mixture consisting of many small crystals in contact with a saturated solution is studied for a period of time, the smallest of the crystals are observed to dissolve while the larger ones grow even larger. Explain this phenomenon in terms of a dynamic equilibrium.

Why doesn't Le Châtelier's principle apply to the removal of some of a solid or pure liquid from a heterogeneous reaction mixture?

Le Châtelier's principle qualitatively describes what will occur if a reactant or product is added or removed from a reaction mixture. Describe as many ways as possible to remove a reactant or product from a mixture at equilibrium.