Question

Consider the following reaction: A(g)⇌B(g)+C(g) Find the equilibrium concentrations of A, B, and C for each of the following different values of Kc. Assume that the initial concentration of A in each case is 1.0 M and that the reaction mixture initially contains no products. Make any appropriate simplifying assumptions. Kc=1.4 Kc=1.2*10^-2 Kc=1.2*10^-5

Answer 1

K = B*C/A

in equilibrium

[A] = 1 - x

[B] = 0 + x

[C] = 0 +x

for

simplify

K = B*C/A

K = (x*x)/(1-x)

K = x^2/(1-x)

x^2 = K -Kx

x^2 + Kx - K = 0

a)

Kc1 = 1.4

x^2 + Kx - K = 0

solve for x

0.67

[A] = 1 - x = 1-0.67 = 0.33

[B] = 0 + x = 0.67

[C] = 0 +x = 0.67

b)

Kc1 = 1.2*10^-2

x^2 + Kx - K = 0

solve for x

x = 0.1037

[A] = 1 - x = 1-0.1037= 0.8963

[B] = 0 + x = 0.1037

[C] = 0 +x = 0.1037

c)

Kc1 = 1.2*10^-5

x^2 + Kx - K = 0

solve for x

x = 0.003458

[A] = 1 - x = 1-0.003458= 0.996542

[B] = 0 + x = 0.003458

[C] = 0 +x = 0.003458