At a certain temperature, this reaction establishes an equilibrium with the given equilibrium constant, kc. if, at this temperature, 2.20 mol of a and 3.70 mol of b are placed in a 1.00-l container, what are the concentrations of a, b, and c at equilibrium?

Respuesta :

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Answer:

[tex][C]_{eq}=4(0.733M)=2.932M[/tex]

[tex][A]_{eq}=2.20M-3(0.733M)=0.001M[/tex]

[tex][B]_{eq}=3.70M-2(0.733M)=2.23M[/tex]

Explanation:

Hello,

In this case, probably, the undergoing chemical reaction is:

[tex]3A(g)+2B(g)<-->4C(g)[/tex]

Nonetheless, the equilibrium constant is not given, but could be assumed, therefore, let me assume it is 1.13x10¹⁹ (very close to a constant I found for a similar exercise on the Ethernet), thus, the initial concentrations of A and B are computed below based on the given moles and the container volume:

[tex][A]_0=\frac{2.20mol}{1.00L} =2.20M[/tex]

[tex][B]_0=\frac{3.70mol}{1.00L} =3.70M[/tex]

In such a way, by applying the law of mass action in addition to the ICE table, the equilibrium statement turn out into:

[tex]Kc=\frac{[C]_{eq}^4}{[A]_{eq}^3[B]_{eq}^2}[/tex]

Now, by inserting the initial concentrations of both A and B and the reaction change, [tex]x[/tex], one obtains:

[tex]1.13x10^{19}=\frac{(4x)^4}{(2.20M-3x)^3(3.70M-2x)^2}[/tex]

Such equation is a highly non-lineal one, that is why we must apply a method such as Newton-Raphson to compute the roots which define the value of the change [tex]x[/tex], thus, after applying it, the roots are:

[tex]x_1=0.733\\x_2=1.85[/tex]

The valid root is [tex]x_1=0.733[/tex] as the other one produces a negative concentration of A at equilibrium, therefore, the requested concentration turn out into:

[tex][C]_{eq}=4(0.733M)=2.932M[/tex]

[tex][A]_{eq}=2.20M-3(0.733M)=0.001M[/tex]

[tex][B]_{eq}=3.70M-2(0.733M)=2.23M[/tex]

However, you can just modify Kc if is different to the one I assumed and perform the Newton-Raphson method to compute the adequate root.

Best regards.