La constante d'équilibre K1 pour l'équilibre N2 O(g)+1 / 2 O2( g) ⇌2 NO(g) vaut 0,97 à 298 K. a

step 1 I'll be going over question number 48. And it gives you the case you value, gives you an equatio

La constante d'équilibre K1 pour l'équilibre N2 O(g)+1 / 2...

La constante d'équilibre $K_1$ pour l'équilibre $$ \mathrm{N}_2 \mathrm{O}(\mathrm{g})+1 / 2 \mathrm{O}_2(\mathrm{~g}) \rightleftharpoons 2 \mathrm{NO}(\mathrm{g}) $$ vaut 0,97 à $298 \mathrm{~K}$. a) Sa valeur $\left(K_2\right)$ est-elle différente si l'équation stœchiométrique est écrite : $$ 2 \mathrm{~N}_2 \mathrm{O}(\mathrm{g})+\mathrm{O}_2(\mathrm{~g}) \rightleftharpoons 4 \mathrm{NO}(\mathrm{g}) $$ b) Quelle serait la constante d'équilibre $K_3$ associée à l'équation stæchiométrique : $$ 4 \mathrm{NO}(\mathrm{g}) \rightleftharpoons 2 \mathrm{~N}_2 \mathrm{O}(\mathrm{g})+\mathrm{O}_2(\mathrm{~g}) $$ c) Si l'on utilise ces constantes d'équilibre pour calculer les pressions partielles des trois gaz à l'équilibre dans des conditions données, trouvera-ton dans les trois cas des valeurs identiques?

La constante d'équilibre $K_1$ pour l'équilibre
$$
\mathrm{N}_2 \mathrm{O}(\mathrm{g})+1 / 2 \mathrm{O}_2(\mathrm{~g}) \rightleftharpoons 2 \mathrm{NO}(\mathrm{g})
$$
vaut 0,97 à $298 \mathrm{~K}$.
a) Sa valeur $\left(K_2\right)$ est-elle différente si l'équation stœchiométrique est écrite :
$$
2 \mathrm{~N}_2 \mathrm{O}(\mathrm{g})+\mathrm{O}_2(\mathrm{~g}) \rightleftharpoons 4 \mathrm{NO}(\mathrm{g})
$$
b) Quelle serait la constante d'équilibre $K_3$ associée à l'équation stæchiométrique :
$$
4 \mathrm{NO}(\mathrm{g}) \rightleftharpoons 2 \mathrm{~N}_2 \mathrm{O}(\mathrm{g})+\mathrm{O}_2(\mathrm{~g})
$$
c) Si l'on utilise ces constantes d'équilibre pour calculer les pressions partielles des trois gaz à l'équilibre dans des conditions données, trouvera-ton dans les trois cas des valeurs identiques?

Key Concepts

Equilibrium Constant

The equilibrium constant is a numerical value that expresses the ratio of the concentrations (or partial pressures) of products to reactants, each raised to the power of their respective stoichiometric coefficients, for a reaction at equilibrium. It is a fundamental thermodynamic property that remains invariant for a given reaction at a specific temperature, regardless of the particular form in which the reaction is written, as long as the relationship between the species is preserved.

Stoichiometric Scaling Rule

When an entire chemical equation is multiplied by a constant factor, the equilibrium constant for the new equation becomes the original constant raised to the power of that factor. This rule reflects the mathematical relationship between the reaction quotient and the stoichiometric coefficients, and it shows that changes in the written form of an equation can alter the numerical value of the constant, even though the underlying equilibrium state remains identical.

Reciprocal Relationship in Reversed Reactions

Reversing a chemical reaction inverts the roles of reactants and products, and therefore, the equilibrium constant for the reverse reaction is the reciprocal of the equilibrium constant for the forward reaction. This reciprocal relationship highlights the fact that the equilibrium position is simply viewed from a different perspective, yet the physical state of equilibrium remains unchanged.

Consistency of Equilibrium Descriptions

Although modifying the stoichiometric coefficients or reversing the direction of a chemical equation affects the numerical expression of the equilibrium constant, when used consistently in calculating equilibrium partial pressures or concentrations, all forms of the equilibrium expression yield the same physical predictions. This consistency underscores that the equilibrium constant is a reflection of the underlying thermodynamic properties of the system rather than the arbitrary form of the reaction equation.

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