Quelle est l'expression du quotient de réaction pour les...

Quelle est l'expression du quotient de réaction pour les équilibres suivants : a) $2 \mathrm{NO}(\mathrm{g})+\mathrm{Cl}_2(\mathrm{~g}) \rightleftharpoons 2 \mathrm{NOCl}(\mathrm{g})$ b) $\mathrm{MgSO}_3(\mathrm{~s}) \rightleftharpoons \mathrm{MgO}(\mathrm{s})+\mathrm{SO}_2(\mathrm{~g})$ c) $\mathrm{HNO}_2$ (aq) $+\mathrm{H}_2 \mathrm{O} \rightleftharpoons \mathrm{H}_3 \mathrm{O}^{+}$(aq) $+\mathrm{NO}_2^{-}$(aq) d) $2 \mathrm{NaHCO}_3(\mathrm{~s}) \rightleftharpoons \mathrm{Na}_2 \mathrm{CO}_3(\mathrm{~S})+\mathrm{H}_2 \mathrm{O}(\mathrm{g})+\mathrm{CO}_2(\mathrm{~g})$ e) $3 \mathrm{Fe}(\mathrm{s})+4 \mathrm{H}_2 \mathrm{O}(\mathrm{g}) \rightleftharpoons \mathrm{Fe}_3 \mathrm{O}_4(\mathrm{~s})+4 \mathrm{H}_2(\mathrm{~g})$ f) $\mathrm{Zn}(\mathrm{s})+2 \mathrm{Ag}^{+}(\mathrm{aq}) \rightleftharpoons \mathrm{Zn}^{2+}(\mathrm{aq})+2 \mathrm{Ag}(\mathrm{s})$

Quelle est l'expression du quotient de réaction pour les équilibres suivants :
a) $2 \mathrm{NO}(\mathrm{g})+\mathrm{Cl}_2(\mathrm{~g}) \rightleftharpoons 2 \mathrm{NOCl}(\mathrm{g})$
b) $\mathrm{MgSO}_3(\mathrm{~s}) \rightleftharpoons \mathrm{MgO}(\mathrm{s})+\mathrm{SO}_2(\mathrm{~g})$
c) $\mathrm{HNO}_2$ (aq) $+\mathrm{H}_2 \mathrm{O} \rightleftharpoons \mathrm{H}_3 \mathrm{O}^{+}$(aq) $+\mathrm{NO}_2^{-}$(aq)
d) $2 \mathrm{NaHCO}_3(\mathrm{~s}) \rightleftharpoons \mathrm{Na}_2 \mathrm{CO}_3(\mathrm{~S})+\mathrm{H}_2 \mathrm{O}(\mathrm{g})+\mathrm{CO}_2(\mathrm{~g})$
e) $3 \mathrm{Fe}(\mathrm{s})+4 \mathrm{H}_2 \mathrm{O}(\mathrm{g}) \rightleftharpoons \mathrm{Fe}_3 \mathrm{O}_4(\mathrm{~s})+4 \mathrm{H}_2(\mathrm{~g})$
f) $\mathrm{Zn}(\mathrm{s})+2 \mathrm{Ag}^{+}(\mathrm{aq}) \rightleftharpoons \mathrm{Zn}^{2+}(\mathrm{aq})+2 \mathrm{Ag}(\mathrm{s})$

Key Concepts

Exclusion of Pure Solids and Liquids in Equilibrium Expressions

In equilibrium expressions, pure solids and liquids are typically omitted because their activities are defined as one owing to their constant density and composition. This simplification is crucial for correctly formulating reaction quotient expressions without unnecessary terms.

Activities and Standard States

Activities express the effective concentration of a species in a mixture and are used in equilibrium expressions to account for non-idealities in behavior. In equilibrium constant expressions, only substances not in their standard state (such as gases in terms of partial pressures or solutes in terms of molarity) are included explicitly, while pure solids and liquids are assigned an activity of 1.

Chemical Equilibrium

Chemical equilibrium refers to the state in a reversible reaction where the rates of the forward and reverse reactions become equal, leading to constant concentrations of reactants and products. It is a fundamental concept in chemical thermodynamics that helps in understanding how reactions balance under given conditions.

Reaction Quotient (Q)

The reaction quotient, Q, is an expression that quantifies the relative amounts of products and reactants present during a reaction at any point in time, using the same mathematical form as the equilibrium constant. It is calculated by raising the activities (or concentrations/pressures) of the products to the power of their stoichiometric coefficients and dividing by those of the reactants.

Transcript

Please give Ace some feedback