Phosgene is a potent chemical warfare agent that is now outlawed by international agreement. it decomposes by the reaction: cocl2 (g) ⇋ co (g) + cl2 (g) kc = 7.5 x 10-5 (at 362°c) calculate the concentration of co when 7.73 mol of phosgene decomposes and reaches equilibrium in a 10.0 liter flask. multiply your answer by 103 and enter that number to 2 decimal places. hint: look at sample problem 17.9 in the 8th ed of silberberg. write a kc expression. calculate the initial concentration of phosgene. do an ice chart. find the concentration of co.

[CO] = 7.61x10⁻³M

7.61x10⁻³x10³ = 7.61

Explanation:

For a generic equation aA + bB ⇄ cC + dD, the constant of equilibrium (Kc) is:

We need to know the molar concentrations in the equilibrium. In the beginning, there is only COCl₂, and its concentration is the number of moles divided by the volume:

[COCl₂] = 7.73/10.0 = 0.773 M

So, the equilibrium will be:

COCl₂(g) ⇆ CO(g) + Cl₂(g)

0.773             0           0      Initial

-x                    +x         +x     Reacts

0.773-x            x           x       Equilibrium

Supposing that x<<0.773, then:

7.5x10⁻⁵ = x²/0.773

x² = 5.7975x10⁻⁵

x = √5.7975x10⁻⁵

x = 7.61x10⁻³ M

The supposing is correct, so [CO] = 7.61x10⁻³ x 10³ = 7.61