For the reaction, 2 SO2(g) + O2(g) == 2 SO3(g), at 450.0 K (Kelvin) the equilibrium constant, Kc, has a value of 4.62. A system was charged to give these initial concentrations, (SO3) = 0.254 M and (O2) = 0.00855 M, and (SO2) = 0.500 M. In which direction will it go?
A. to the right
B. to the left
C. it will remain at the same concentrations
D. not enough data to tell
I think that it will remain the same.
Is this correct?
You need to substitute into the Keq expression (called the reaction quotient when you put the INITIAL values in) and compare that with Kc. I don't think D is correct.
To determine which direction the reaction will proceed, we can compare the current concentrations of the reactants and products to the equilibrium concentrations.
Since the equilibrium constant is given as Kc = 4.62, we can set up the equilibrium expression:
Kc = [SO3]^2 / ([SO2]^2 * [O2])
Plugging in the initial concentrations:
Kc = (0.254)^2 / ((0.5)^2 * (0.00855))
Kc = 12.92
Since the initial concentration of SO3 (0.254 M) is greater than the equilibrium concentration (determined by Kc = 4.62), the reaction will shift towards the left to reduce the concentration of SO3 and establish a new equilibrium.
Therefore, the answer is B. to the left.
To determine the direction in which a reaction will proceed, you can use the principles of Le Chatelier's principle and the reaction's equilibrium constant.
In this case, the equilibrium constant (Kc) is given as 4.62 at 450.0 K. Kc is defined as the ratio of the concentrations of the products to the concentrations of the reactants, with each concentration raised to the power of its stoichiometric coefficient in the balanced equation.
Given the initial concentrations:
(SO3) = 0.254 M,
(O2) = 0.00855 M, and
(SO2) = 0.500 M,
We can calculate the value of the reaction quotient, Qc, by substituting these initial concentrations into the equilibrium expression:
Qc = ([SO3]^2) / ([SO2]^2 * [O2])
Qc = (0.254^2) / ((0.500^2) * 0.00855)
Qc = 0.2576 / 0.002145
Qc = 120.19
If Qc is less than Kc (Qc < Kc), the reaction will proceed to the right (in the forward direction) to reach equilibrium by forming more products. If Qc is greater than Kc (Qc > Kc), the reaction will proceed to the left (in the reverse direction) to reach equilibrium by forming more reactants. If Qc is equal to Kc (Qc = Kc), the system is already at equilibrium, and there will be no net change.
Comparing the calculated Qc value of 120.19 to the given Kc value of 4.62, we can see that Qc is significantly greater than Kc. Therefore, the reaction will proceed to the left (in the reverse direction) to reach equilibrium by decreasing the concentrations of the products (SO3) and (O2) and increasing the concentration of (SO2).
So, in this case, the correct answer is:
B. to the left, meaning the reaction will proceed in the reverse direction by forming more reactants (SO2 and O2) and decreasing the concentrations of the products (SO3).
Therefore, your initial assumption that the system will remain at the same concentrations is incorrect.