### Question 2: Equilibrium and Kinetics (20 points)

A. In certain conditions, the equilibrium concentrations for components in the reaction [tex]2 \text{NOCl}(g) \rightleftharpoons 2 \text{NO}(g) + \text{Cl}_2(g)[/tex] are [tex][\text{NO}] = 0.02 \text{M}[/tex], [tex][\text{Cl}_2] = 0.01 \text{M}[/tex], and [tex][\text{NOCl}] = 0.5 \text{M}[/tex]. What is the value of [tex]K_e[/tex] given [tex]K_{\text{eq}} = \frac{[\text{NO}]^2[\text{Cl}_2]}{[\text{NOCl}]^2}[/tex]? (4 points)



Answer :

To find the equilibrium constant [tex]\( K_{\text{eq}} \)[/tex] for the reaction [tex]\( 2 NOCl (g) \rightleftharpoons 2 NO (g) + Cl_2 (g) \)[/tex], we can make use of the provided equilibrium concentrations and the given formula for [tex]\( K_{\text{eq}} \)[/tex]:

[tex]\[ K_{\text{eq}} = \frac{[NO]^2 [Cl_2]}{[NOCl]^2} \][/tex]

Step-by-step solution:

1. Identify the provided equilibrium concentrations:
- [tex]\([NO] = 0.02 \, \text{M}\)[/tex]
- [tex]\([Cl_2] = 0.01 \, \text{M}\)[/tex]
- [tex]\([NOCl] = 0.5 \, \text{M}\)[/tex]

2. Substitute these values into the equilibrium constant expression:
[tex]\[ K_{\text{eq}} = \frac{(0.02)^2 \times 0.01}{(0.5)^2} \][/tex]

3. Calculate the numerator:
- [tex]\((0.02)^2 = 0.0004\)[/tex]
- [tex]\(0.0004 \times 0.01 = 0.000004\)[/tex]

4. Calculate the denominator:
- [tex]\((0.5)^2 = 0.25\)[/tex]

5. Divide the numerator by the denominator:
[tex]\[ K_{\text{eq}} = \frac{0.000004}{0.25} = 0.000016 \][/tex]

6. Therefore, the value of the equilibrium constant [tex]\( K_{\text{eq}} \)[/tex] is:

[tex]\[ K_{\text{eq}} = 1.6 \times 10^{-5} \][/tex]

Hence, the equilibrium constant [tex]\( K_{\text{eq}} \)[/tex] for the given reaction under the specified conditions is [tex]\( 1.6 \times 10^{-5} \)[/tex].