Using the Equilibrium Constant Part A Constants I Periodic Table Inisally, only
ID: 576448 • Letter: U
Question
Using the Equilibrium Constant Part A Constants I Periodic Table Inisally, only A and B are present, each at 2.00 M. What is the final concentration of A once equilibrium is reached? Express your answer to two significant figures and include the appropriate units View Available Hint(s) The reversible chemical reaction A +BC+D has the following equilibrium constant AValue Units Submit Part B What is the final concentration of D at equilibrium if the initial concentrations are [A] 1.00 M and B Express your answer to two significant figures and include the appropriate units. View Available Hint(s) -2.00 M ? DValue Units SubmitExplanation / Answer
A)
ICE Table:
[A] [B] [C] [D]
initial 2.0 2.0 0 0
change -1x -1x +1x +1x
equilibrium 2.0-1x 2.0-1x +1x +1x
Equilibrium constant expression is
Kc = [C]*[D]/[A]*[B]
5.7 = (1*x)^2/(2-1*x)^2
sqrt(5.7) = (1*x)/(2-1*x)
2.387 = (1*x)/(2-1*x)
4.77493 - 2.38747*x = 1*x
4.77493-3.38747*x = 0
x = 1.41
At equilibrium:
[A] = 2.0-1x = 2.0-1*1.41 = 0.59 M
Answer: 0.59 M
B)
ICE Table:
[A] [B] [C] [D]
initial 1.0 2.0 0 0
change -1x -1x +1x +1x
equilibrium 1.0-1x 2.0-1x +1x +1x
Equilibrium constant expression is
Kc = [C]*[D]/[A]*[B]
5.7 = (1*x)(1*x)/((1-1*x)(2-1*x))
5.7 = (1*x^2)/(2-3*x + 1*x^2)
11.4-17.1*x + 5.7*x^2 = 1*x^2
11.4-17.1*x + 4.7*x^2 = 0
This is quadratic equation (ax^2+bx+c=0)
a = 4.7
b = -17.1
c = 11.4
Roots can be found by
x = {-b + sqrt(b^2-4*a*c)}/2a
x = {-b - sqrt(b^2-4*a*c)}/2a
b^2-4*a*c = 78.09
roots are :
x = 2.759 and x = 0.8791
x can't be 2.759 as this will make the concentration negative.so,
x = 0.8791
At equilibrium:
[D] = x = 0.8791 M
Answer: 0.88 M
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