To write the equilibrium expression for the reaction:
[tex]\[
2 \, \text{NO}_{(g)} + \text{O}_2{(g)} \longleftrightarrow 2 \, \text{NO}_2{(g)}
\][/tex]
follow these steps:
1. Identify the Reactants and Products:
- Reactants: [tex]\(\text{NO}_{(g)}\)[/tex] and [tex]\(\text{O}_2{(g)}\)[/tex]
- Product: [tex]\(\text{NO}_2{(g)}\)[/tex]
2. Understand the General Form of the Equilibrium Expression:
For a general reaction of the form:
[tex]\[
aA + bB \longleftrightarrow cC + dD
\][/tex]
The equilibrium constant expression ([tex]\(K_c\)[/tex]) is given by:
[tex]\[
K_c = \frac{[\text{C}]^c [\text{D}]^d}{[\text{A}]^a [\text{B}]^b}
\][/tex]
Here, [tex]\( [\text{A}] \)[/tex] denotes the concentration of substance [tex]\( \text{A} \)[/tex], and the exponents are the stoichiometric coefficients from the balanced chemical equation.
3. Apply the Form to the Given Reaction:
For the reaction:
[tex]\[
2 \, \text{NO}_{(g)} + \text{O}_2{(g)} \longleftrightarrow 2 \, \text{NO}_2{(g)}
\][/tex]
The equilibrium expression is formulated by identifying the concentrations of the reactants and products and their stoichiometric coefficients:
[tex]\[
K_c = \frac{[\text{NO}_2]^{2}}{[\text{NO}]^{2} [\text{O}_2]}
\][/tex]
Therefore, the equilibrium expression for the given reaction is:
[tex]\[
K_c = \frac{[\text{NO}_2]^{2}}{[\text{NO}]^{2} [\text{O}_2]}
\][/tex]
