Phosphorus pentachloride decomposes according to the chemical equation pcl5(g)↽−−⇀pcl3(g)+cl2(=1.80 at 250 ∘c a 0.197 mol sample of pcl5(g) is injected into an empty 2.90 l reaction vessel held at 250 ∘c. calculate the concentrations of pcl5(g) and pcl3(g) at equilibrium.

The concentration of  is 0.0655 M and  is 0.00240 M at equilibrium.

Given:

Moles of phosphorus pentachloride added to flask = 0.197 mol

The volume of the flask = 2.90

To find:

The concentrations of and at equilibrium.

Solution:

Initial concentration of phosphorus pentachloride in flask:

The equilibrium constant of the reaction =

The equilibrium concentration of phosphorus trichloride =

The equilibrium concentration of chlorine gas =

The equilibrium concentration of phosphorus pentachloride

The expression of an equilibrium constant will be given as:

The equilibrium concentration of phosphorus pentachloride:

The equilibrium concentration of chlorine gas :

The concentration of  is 0.00240 M and  is 0.0655 M at equilibrium.

Learn more about the equilibrium constant here:

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[Cl₂] = 0.0656 mol·L⁻¹; [PCl₅] = 0.002 37 mol·L⁻¹

Explanation:

The balanced equation is

PCl₅ ⇌ PCl₃ + Cl₂

Data:

Kc = 1.80

n = 0.197 mol

V = 2.90 L

1. Calculate the initial concentration of PCl₅

Step 2. Set up an ICE table.

Step 3. Calculate the equilibrium concentrations

[Cl₂] = x mol·L⁻¹ = 0.0656 mol·L⁻¹

[PCl₅] = (0.06793 - 0.0656) mol·L⁻¹ = 0.00237 mol·L⁻¹

Check:

Close enough.