Write equilibrium constant expressions for \(K_{\mathrm{c}}\) and for \(K_{P}\), if applicable, for these processes: (a) \(2 \mathrm{CO}_{2}(g) \rightleftharpoons 2 \mathrm{CO}(g)+\mathrm{O}_{2}(g)\) (b) \(3 \mathrm{O}_{2}(g) \rightleftharpoons 2 \mathrm{O}_{3}(g)\) (c) \(\mathrm{CO}(g)+\mathrm{Cl}_{2}(g) \rightleftharpoons \mathrm{COCl}_{2}(g)\) (d) \(\mathrm{H}_{2} \mathrm{O}(g)+\mathrm{C}(s) \rightleftharpoons \mathrm{CO}(g)+\mathrm{H}_{2}(g)\) (e) \(\mathrm{HCOOH}(a q) \rightleftharpoons \mathrm{H}^{+}(a q)+\mathrm{HCOO}^{-}(a q)\) (f) \(2 \mathrm{HgO}(s) \rightleftharpoons 2 \mathrm{Hg}(l)+\mathrm{O}_{2}(g)\)

Short Answer

Expert verified
The equilibrium constant expressions for each set can be summarized as follows: (a) \(K_{\mathrm{c}} = \frac{[\mathrm{CO}]^2\times [\mathrm{O}_{2}]}{[\mathrm{CO}_{2}]^2}\) and \(K_{P} = \frac{(P_{\mathrm{CO}})^{2}\times P_{\mathrm{O}_{2}}}{(P_{\mathrm{CO}_{2}})^{2}}\), (b) \(K_{\mathrm{c}} = \frac{[\mathrm{O}_{3}]^2}{[\mathrm{O}_{2}]^3}\) and \(K_{P} = \frac{(P_{\mathrm{O}_{3}})^{2}}{(P_{\mathrm{O}_{2}})^{3}}\), (c) \(K_{\mathrm{c}} = \frac{[\mathrm{COCl}_{2}]}{\mathrm{[CO]}\times\mathrm{[Cl}_{2}]}\) and \(K_{P} = \frac{P_{\mathrm{COCl}_{2}}}{P_{\mathrm{CO}}\times P_{\mathrm{Cl}_{2}}}\), (d) \(K_{\mathrm{c}} = \frac{\mathrm{[CO]}\times \mathrm{[H}_{2}]}{\mathrm{[H}_{2}\mathrm{O}}\) and \(K_{P} = \frac{P_{\mathrm{CO}}\times P_{\mathrm{H}_{2}}}{P_{\mathrm{H}_{2}\mathrm{O}}}\), (e) \(K_{\mathrm{c}} = \frac{\mathrm{[H}^{+}\mathrm{]}\times \mathrm{[HCOO}^{-}]}{\mathrm{[HCOOH]}}\), and (f) \(K_{\mathrm{c}} = [\mathrm{O}_{2}]\) and \(K_{P} = P_{\mathrm{O}_{2}}\).

Step by step solution

01

Theory: Definition of \(K_{\mathrm{c}}\) and \(K_{P}\)

The concentration equilibrium constant, \(K_{\mathrm{c}}\), for a general reaction \[aA + bB \rightleftharpoons cC + dD\] is given by \[K_{\mathrm{c}} = \frac{[C]^c [D]^d}{[A]^a [B]^b}\]Meanwhile, the pressure equilibrium constant, \(K_{P}\), is defined similarly, but using partial pressures of the gases, \[K_{P} = \frac{(P_C)^c (P_D)^d}{(P_A)^a (P_B)^b}.\]Let's apply this to the six reactions given, remembering not to include solids or liquids in the expressions.
02

(a) CO₂ and CO reaction

The reaction is \(2 \mathrm{CO}_{2}(g) \rightleftharpoons 2 \mathrm{CO}(g)+\mathrm{O}_{2}(g)\). For \(K_{\mathrm{c}}\), we get\[K_{\mathrm{c}} = \frac{(\mathrm{[CO]})^{2}\times [\mathrm{O}_{2}]}{(\mathrm{[CO}_{2}])^{2}}\]Since all species are gases, we can also find \(K_{P}\),\[K_{P} = \frac{(P_{\mathrm{CO}})^{2}\times P_{\mathrm{O}_{2}}}{(P_{\mathrm{CO}_{2}})^{2}}.\]
03

(b) O₂ and O₃ reaction

The reaction is \(3 \mathrm{O}_{2}(g) \rightleftharpoons 2 \mathrm{O}_{3}(g)\).Similar to (a),\[K_{\mathrm{c}} = \frac{(\mathrm{[O}_{3}])^{2}}{(\mathrm{[O}_{2}])^{3}},\]and\[K_{P} = \frac{(P_{\mathrm{O}_{3}})^{2}}{(P_{\mathrm{O}_{2}})^{3}}.\]
04

(c) CO and Cl₂ reaction

The reaction is \(\mathrm{CO}(g)+\mathrm{Cl}_{2}(g) \rightleftharpoons \mathrm{COCl}_{2}(g)\).Following the same process, \[K_{\mathrm{c}} = \frac{\mathrm{[COCl}_{2}]}{\mathrm{[CO]}\times\mathrm{[Cl}_{2}]},\]and\[K_{P} = \frac{P_{\mathrm{COCl}_{2}}}{P_{\mathrm{CO}}\times P_{\mathrm{Cl}_{2}}}.\]
05

(d) H₂O and C reaction

The reaction is \(\mathrm{H}_{2} \mathrm{O}(g)+\mathrm{C}(s) \rightleftharpoons \mathrm{CO}(g)+\mathrm{H}_{2}(g)\). Here \(\mathrm{C}(s)\) is a solid, therefore it will not appear in the expressions. So, \[K_{\mathrm{c}} = \frac{\mathrm{[CO]}\times \mathrm{[H}_{2}\mathrm{]}}{\mathrm{[H}_{2}\mathrm{O}(g)}\]and\[K_{P} = \frac{P_{\mathrm{CO}}\times P_{\mathrm{H}_{2}}}{P_{\mathrm{H}_{2}\mathrm{O}}}.\]
06

(e) Reaction of HCOOH

Here, \(\mathrm{HCOOH}(a q) \rightleftharpoons \mathrm{H}^{+}(a q)+\mathrm{HCOO}^{-}(a q)\). As this reaction is in aqueous solution, only \(K_{\mathrm{c}}\) is applicable. \[K_{\mathrm{c}} = \frac{\mathrm{[H}^{+}\mathrm{]}\times \mathrm{[HCOO}^{-}\mathrm{]}}{\mathrm{[HCOOH]}}.\]
07

(f) HgO and Hg reaction

Finally, \(2 \mathrm{HgO}(s) \rightleftharpoons 2 \mathrm{Hg}(l)+\mathrm{O}_{2}(g)\). The \(\mathrm{HgO}(s)\) is a solid and \(\mathrm{Hg}(l)\) is a liquid, so only the O₂(g) appears in the expressions. This gives \[K_{\mathrm{c}} = [\mathrm{O}_{2}],\]and\[K_{P} = P_{\mathrm{O}_{2}}.\]

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Most popular questions from this chapter

Consider the following equilibrium process at \(700^{\circ} \mathrm{C}\) $$ 2 \mathrm{H}_{2}(g)+\mathrm{S}_{2}(g) \rightleftharpoons 2 \mathrm{H}_{2} \mathrm{~S}(g) $$ Analysis shows that there are 2.50 moles of \(\mathrm{H}_{2}, 1.35 \times\) \(10^{-5}\) mole of \(\mathrm{S}_{2}\), and 8.70 moles of \(\mathrm{H}_{2} \mathrm{~S}\) present in a 12.0-L flask at equilibrium. Calculate the equilibrium constant \(K_{\mathrm{c}}\) for the reaction.

Define equilibrium. Give two examples of a dynamic equilibrium.

Write the equation relating \(K_{\mathrm{c}}\) and \(K_{P}\) and define all the terms.

When a gas was heated under atmospheric conditions, its color was found to deepen. Heating above \(150^{\circ} \mathrm{C}\) caused the color to fade, and at \(550^{\circ} \mathrm{C}\) the color was barely detectable. However, at \(550^{\circ} \mathrm{C}\), the color was partially restored by increasing the pressure of the system. Which of these best fits this description? Justify your choice. (a) A mixture of hydrogen and bromine, (b) pure bromine, (c) a mixture of nitrogen dioxide and dinitrogen tetroxide. (Hint: Bromine has a reddish color and nitrogen dioxide is a brown gas. The other gases are colorless.)

In the uncatalyzed reaction $$ \mathrm{N}_{2} \mathrm{O}_{4}(g) \rightleftharpoons 2 \mathrm{NO}_{2}(g) $$ at \(100^{\circ} \mathrm{C}\) the pressures of the gases at equilibrium are \(P_{\mathrm{N}_{2} \mathrm{O}_{4}}=0.377 \mathrm{~atm}\) and \(P_{\mathrm{NO}_{2}}=1.56 \mathrm{~atm} .\) What would happen to these pressures if a catalyst were present?

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