Answer:
Step-by-step explanation:
To calculate the equilibrium constant (Kc) for the reaction, we can use the formula:
Kc = [SO2] * [NO2] / [SO3] * [NO]
Given the initial concentrations ([SO3] = 2.55 M and [NO] = 1.90 M) and the equilibrium concentrations ([SO3] = 1.85 M and [NO] = 1.20 M), we can plug these values into the formula:
Kc = (1.85 M * [NO2]) / (1.20 M * 2.55 M)
Now, we need to find the equilibrium concentrations of SO2 and NO2.
From the balanced chemical equation:
SO3(g) + NO(g) ⇌ SO2(g) + NO2(g)
We can see that the stoichiometric coefficients of SO3 and SO2 are the same, and similarly, the stoichiometric coefficients of NO and NO2 are the same.
At equilibrium, the change in concentration of SO3 and NO will be equal to the change in concentration of SO2 and NO2. Let's denote the change in concentration as "x".
[SO3] = 2.55 M - x
[NO] = 1.90 M - x
[SO2] = x
[NO2] = x
Now, we can plug these values into the Kc expression:
Kc = (1.85 M * x) / ((1.20 M - x) * (2.55 M - x))
Now, we can use the given equilibrium concentrations to solve for "x":
[SO3] at equilibrium = 1.85 M
[NO] at equilibrium = 1.20 M
1.85 M = 2.55 M - x
x = 2.55 M - 1.85 M
x = 0.70 M
Now, we can calculate Kc:
Kc = (1.85 M * 0.70 M) / ((1.20 M - 0.70 M) * (2.55 M - 0.70 M))
Kc = 1.2955 / (0.5 M * 1.85 M)
Kc ≈ 1.75 (rounded to two decimal places)
The equilibrium constant (Kc) for the reaction is approximately 1.75.