Question

Consider the following reaction: COCl2(g) ⇌ CO(g) + Cl2(g) A reaction mixture initially contains 1.6 M COCl2. Determine the equilibrium concentration of CO if Kc for the reaction at this temperature is 8.33 × 10-4 (Hint: Note the size of Kc).

Answer 1

Answer:

The equilibrium concentration of CO is 0.0361 M

Explanation:

Step 1: Data given

Kc = 8.33 *10^-4

Molarity of COCl2 = 1.6 M

Step 2: The balanced equation:

COCl2(g) ⇌ CO(g) + Cl2(g)

Step 3: Calculate final concentrations

The initial concentration of COCl2 = 1.6M

The initial concentration of CO and Cl2 = 0M

There will react xM of COCl2

Since the mole ratio is 1:1

The final concentration of CO and Cl2 will be X M

The final concentration of COCl2 will be (1.6 -X)M

Step 4: Define Kc

Kc=  [CO] *[Cl2] /  [COCl2]  = 8.33*10^-4

Kc = X*X / 1.6-X = 8.33 * 10^-4

8.33 * 10^-4  = X² /(1.6-X)

8.33 * 10^-4 *(1.6 -X) = X²

0.0013328 - 8.33*10^-4 X = X²

X² + 8.33*10^-4 X  - 0.0013328= 0

X = 0.0361 M = [CO] = [Cl2]

[COCl2] = 1.6 - 0.0361 = 1.5639 M

To control this we can calculate the Kc

(0.0361*0.0361)/1.5639 = 0.000833