Given the equilibrium system PCl5(g) <---> PCl3(g) + Cl2(g)
K = 12.5 at 60 degrees Celsius. A 1.0-L reaction vessel is analyzed and found to contain 3.2 mol Cl2(g), 1.5 mol PCL3(g) and 3.0 mol PCl5(g). Show that the reaction mixture has not yet reached equilibrium
Write the equilibrium equation.
Write the Keq expression.
Plug in the values given for concns at equilibrium and compare with Keq of 12.5 which is given. You may logically conclude that the system is or is not at equilibrium AND whether it is too much on the reactant side OR too much to the product side. Show your work if this is not clear or to check your answers.
To determine whether the reaction mixture has reached equilibrium, we need to compare the current concentrations of the reactants and products to their equilibrium concentrations. This can be done by calculating the reaction quotient (Q) and comparing it to the equilibrium constant (K).
The reaction quotient (Q) is calculated in the same way as the equilibrium constant (K), but using the current concentrations of the reactants and products instead of their equilibrium concentrations.
For the reaction PCl5(g) ⇌ PCl3(g) + Cl2(g), the reaction quotient (Q) can be calculated as follows:
Q = [PCl3] * [Cl2] / [PCl5]
Given that the initial concentrations of Cl2, PCl3, and PCl5 are 3.2 mol, 1.5 mol, and 3.0 mol respectively and the volume of the reaction vessel is 1.0 L, we can substitute these values into the reaction quotient equation:
Q = (1.5 mol) * (3.2 mol) / (3.0 mol)
Q = 4.8
Since Q (4.8) is not equal to K (12.5), we can conclude that the reaction mixture has not yet reached equilibrium.
When Q is less than K, it means that the reaction has not yet produced enough products to reach equilibrium. On the other hand, when Q is greater than K, it means that the reaction has exceeded the equilibrium concentration of products and needs to shift in the reverse direction to reach equilibrium.
In this case, Q (4.8) is less than K (12.5), indicating that the forward reaction has not yet produced enough PCl3 and Cl2 to reach equilibrium.