Which will not appear in the equilibrium constant expression for the reaction below?
[tex]H_2 O(g)+C(s) \longleftrightarrow H_2(g)+CO(g)[/tex]
A. [C]
B. [tex][H _2][/tex]
Answer (2)
The equilibrium constant expression includes only gaseous and aqueous species, not solids or liquids.
In the reaction H 2 O ( g ) + C ( s ) ⟷ H 2 ( g ) + CO ( g ) , carbon (C) is a solid.
Therefore, [C] will not appear in the equilibrium constant expression.
The final answer is [C]. [ C ]
Explanation
Understanding the Problem The problem asks us to identify which species from the given options will not appear in the equilibrium constant expression for the reaction: H 2 O ( g ) + C ( s ) ⟷ H 2 ( g ) + CO ( g ) The options are [C] and [ H 2 ] .
Equilibrium Constant Expression The equilibrium constant expression, K c , is a ratio of the concentrations of the products to the reactants, each raised to the power of their stoichiometric coefficients. However, only gaseous and aqueous species are included in the expression; solids and liquids are excluded.
Identifying Phases and Writing the Expression In the given reaction, we have:
H 2 O ( g ) : gas
C ( s ) : solid
H 2 ( g ) : gas
CO ( g ) : gas Therefore, the equilibrium constant expression will be: K c = [ H 2 O ] [ H 2 ] [ CO ] Note that the solid carbon, C ( s ) , is not included in the expression.
Determining the Answer Comparing the equilibrium constant expression with the given options, we see that [C] will not appear in the expression, while [ H 2 ] does appear.
Examples
Understanding equilibrium constants is crucial in many real-world applications. For example, in the Haber-Bosch process, nitrogen and hydrogen react to form ammonia, a key ingredient in fertilizers. By manipulating the equilibrium conditions (temperature, pressure, and concentration), we can maximize the production of ammonia. Similarly, in environmental science, understanding equilibrium helps predict the distribution of pollutants in different phases (air, water, and soil). In the pharmaceutical industry, equilibrium principles are used to optimize drug synthesis and delivery. These examples highlight the broad applicability of equilibrium concepts in various fields.
In the given reaction, only gaseous and aqueous species are included in the equilibrium constant expression. Since carbon (C) is a solid, it does not appear in the expression. Therefore, the correct answer is [C].
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