At a very high temperature, Kc=65.0 for the following reaction.

Question

2HI H2+I2
The following concentrations were detected in a mixture. Is the system at equilibrium? If not, in which direction must the reaction proceed for equilibrium to be established?
(HI) =0.500M, (H2) =2.80M, and (I2)=3.40M

Answer 1

To determine if the system is at equilibrium, we can calculate Qc, the reaction quotient, using the given concentrations:

Qc = [H2][I2]/[HI]^2

Plugging in the given values, we get:

Qc = (2.80)(3.40)/(0.500)^2 = 38.08

Since Kc = 65.0 and Qc = 38.08, the system is not at equilibrium.

To establish equilibrium, the reaction must proceed in the direction that will increase the value of Qc. Since Qc is smaller than Kc, it means that the concentrations of H2 and I2 are too low and the concentration of HI is too high compared to the equilibrium conditions. Therefore, the reaction must proceed in the forward direction to increase the concentrations of H2 and I2 and decrease the concentration of HI until Qc reaches the value of Kc.