Explore a diverse range of topics and get answers from knowledgeable individuals on IDNLearn.com. Ask any question and receive timely, accurate responses from our dedicated community of experts.

Phosphorus trichloride reacts with chlorine to form phosphorus pentachloride.
PCl3(g) + Cl2(g)=
PCl5(g)
0.75 mol of PCl3 and 0.75 mol of Cl2 are placed in a 8.0L reaction vessel at 500K.
What is the equilibrium concentration of the mixture? The value of Kc at 500K is 49.
(6 marks)​


Sagot :

Answer:

[PCl₃] = [Cl₂] = 0.035M

[PCl₅] = 0.059M

Explanation:

Based on the chemical reaction, Kc is:

Kc = 49 = [PCl₅] / [PCl₃] [Cl₂]

Where [] are the concentrations in equilibrium of each species

The initial concentration of the reactants is:

[PCl₃] = [Cl₂] = 0.75mol / 8.0L =  0.094M

The reactants must be consumed whereas PCl₅ will be produced. That is:

[PCl₃] = [Cl₂] = 0.094M - X

[PCl₅] = X

Where X is the reaction coordinate

Replacing in Kc expression:

49 = [X] / [0.094 - X] [0.094 - X]

49 = [X] / 0.008836 - 0.188 X + X²

0.432964 - 9.212 X + 49 X² = X

0.432964 - 10.212 X + 49 X² = 0

Solving for X

X = 0.059M → Right solution

X = 0.15M → False solution. Will produce negative concentrations

Replacing:

[PCl₃] = [Cl₂] = 0.094M - 0.059M = 0.035M

[PCl₅] = 0.059M

[PCl₃] = [Cl₂] = 0.035M

[PCl₅] = 0.059M