A(g)+ B(g) <---> C(g) + D(g)
Kc= 144. If .4 mol of A and B are placed in a 2 Liter container, what will be the concentration of C at equilibrium?
I said the concentration of A= .2 because (.4/2=.2)
and because 1 mol of A = 1 mol of C,
the concentration of C also = .2
But the answer was .185. What did I do wrong?
You ignored the fact that the reaction reaches equilibrium subject to the Kc = 144; i.e., your numbers are based on what the reaction STARTED with and not what they are at equilibrium.
...........A + B ==> C + D
initial.0.2M 0.2M ..0...0
change....-x....-x...+x..+x
equil....0.2-x 0.2-x..x...x
Kc = 144 = (x)(x)/(0.2-x)(0.2-x)
Solve for x.
thanks!
To answer this question, you first need to understand how to calculate the concentrations of the reactants and products at equilibrium using the given equilibrium constant (Kc).
In the given equation A(g) + B(g) ⇌ C(g) + D(g), the equilibrium constant Kc can be written as follows:
Kc = [C] * [D] / [A] * [B]
Where [A], [B], [C], and [D] represent the molar concentrations of A, B, C, and D at equilibrium, respectively.
Given that Kc = 144, we can write the equation as follows:
144 = [C] * [D] / ([A] * [B])
Now, when it comes to calculating the concentrations at equilibrium, we have to consider the stoichiometric coefficients in the balanced equation. In this case, we have a 1:1 ratio between A and C.
Given that you placed 0.4 mol of A and B in a 2 L container, their initial concentrations will be:
[A] = 0.4 mol / 2 L = 0.2 M
[B] = 0.4 mol / 2 L = 0.2 M
At equilibrium, let's assume the concentration of C is [C] M. Since the ratio between A and C is 1:1, we can say [C] = [A].
Now, we can rewrite the equation by substituting the known values:
144 = [C] * [D] / (0.2 * 0.2)
Since we assumed [C] = [A], the equation becomes:
144 = [A] * [D] / (0.2 * 0.2)
Simplifying further:
144 * 0.2 * 0.2 = [A] * [D]
So, [A] * [D] = 5.76
Since [A] = 0.2 M, we can solve for [D]:
0.2 M * [D] = 5.76
[D] = 5.76 / 0.2 = 28.8 M
Now, since [C] = [A], the concentration of C at equilibrium is 0.2 M.
Therefore, the correct answer should be 0.2 M, and it seems the given answer of 0.185 M is not accurate.