Consider the following reaction at a certain temperature: PCl₅(g) PCl₃(g) + Cl₂(g)
K_c = 0.100
At equilibrium,[PCl₅] = 2.00 M and [PCl₃] = [Cl₂] = 1.00 M.If suddenly 1.00 M PCl₅(g) ,PCl₃(g) ,and Cl₂(g) is added,what is the equilibrium concentration of Cl₂(g) ?

Question

Consider the following reaction at a certain temperature: PCl₅(g)

Consider the following reaction at a certain temperature: PCl<sub>5</sub>(g) PCl<sub>3</sub>(g) + Cl<sub>2</sub>(g) K<sub>c</sub> = 0.100 At equilibrium,[PCl<sub>5</sub>] = 2.00 M and [PCl<sub>3</sub>] = [Cl<sub>2</sub>] = 1.00 M.If suddenly 1.00 M PCl<sub>5</sub>(g) ,PCl<sub>3</sub>(g) ,and Cl<sub>2</sub>(g) is added,what is the equilibrium concentration of Cl<sub>2</sub>(g) ? A) 3.0 M B) essentially zero C) 0.65 M D) 2.75 M E) 3.35 M

PCl₃(g) + Cl₂(g)
K_c = 0.100
At equilibrium,[PCl₅] = 2.00 M and [PCl₃] = [Cl₂] = 1.00 M.If suddenly 1.00 M PCl₅(g) ,PCl₃(g) ,and Cl₂(g) is added,what is the equilibrium concentration of Cl₂(g) ?

Quizplus · Accepted Answer

Since the reaction is at equilibrium, we can use the equilibrium constant to calculate the initial concentrations of the products and reactants. Using the equilibrium constant expression, we get:

KS1U1B1cS1U1B0 = [PClS1U1B13S1U1B0][ClS1U1B12S1U1B0] / [PClS1U1B15S1U1B0]

Plugging in the given equilibrium concentrations, we get:

0.100 = (1.00)(1.00) / 2.00

Solving for the initial concentration of PCl5, we get:

[PClS1U1B15S1U1B0] = 2.00 M
[PClS1U1B13S1U1B0] = [ClS1U1B12S1U1B0] = 1.00 M
[PClS1U1B5S1U1B0] = (2.00)(0.100) / (1.00) = 0.200 M

Now, when 1.00 M of each species is added, the new concentrations become:

[PClS1U1B15S1U1B0] = 3.00 M
[PClS1U1B13S1U1B0] = 2.00 M
[ClS1U1B12S1U1B0] = 2.00 M

Using the equilibrium constant expression again, we get:

KS1U1B1cS1U1B0 = [PClS1U1B13S1U1B0][ClS1U1B12S1U1B0] / [PClS1U1B15S1U1B0]
0.100 = (2.00)(2.00) / 3.00
0.100 = 1.33 / [ClS1U1B12S1U1B0]
[ClS1U1B12S1U1B0] = 1.33 / 0.100 = 13.3 / 10 = 1.33 M

Therefore, the equilibrium concentration of Cl2 is 1.33 M, which is closest to choice C (0.65 M).

Consider the Following Reaction at a Certain Temperature: PCl5(g)

Consider the Following Reaction at a Certain Temperature: PCl₅(g)