Question

Using the following balanced chemical equation: PCL5 -> PCL3 + CL2 and knowing that Keq = 7.9, [PCL3] = 0.054M and [CL2] = 0.34M

a. write the Keq expression for the reaction
b. find the [PCL5]
c circle the correct answer: the reaction favored is the (forward, reverse)

Answer 1

see explanations

Step-by-step explanation:

PCl₅ => PCl₃ + Cl₂

C(eq): [PCl₅] 0.054M 0.34M

a. Keq = [PCl₃][Cl₂]/[PCl₅]

b. 7.9 = (0.054)(0.34)/[PCl₅] => [PCl₅] = (0.054)(0.34)/(7.9) = 0.0023M

c. If [PCl₃] = 0.054M; [Cl₂] = 0.34M and [PCl₅] = 0.0023M then the reaction is at equilibrium and will not shift forward or in reverse. In order to determine if reaction is not at equilibrium, a set of concentration values needs to be given in problem, used to calculate Qeq and compared to the given Keq value. The following defines direction of shift ...

Keq < Qeq => rxn shifts left

Keq = Qeq => rxn is at equilibrium (no shift)

Keq > Qeq => rxn shifts right

NOTE: If Keq is listed first followed by Qeq in the above conditions, the inequality symbol indicates direction of shift.