Equilibrium Position and the Equilibrium Constant (Kc)

Dependence of the Equilibrium Constant ( $K_c$ ): - The equilibrium constant ( $K_c$ ) is exclusively dependent on temperature. - Temperature Invariance: When the temperature of a system remains constant, the value of the equilibrium constant remains unaffected, regardless of other changes made to the system. - Temperature Variance: When the temperature of a reaction system varies, the equilibrium constant also varies. - Independence from Other Factors: Factors such as concentration, pressure, and volume do not affect the equilibrium constant ( $K_c$ ).
Methodology for Analysis: When the effect of one specific factor is being evaluated, all other factors are held constant to observe the singular impact on the system.

Increasing Reactant Concentration: - When the concentration of a reactant is increased, the equilibrium position shifts to the right, also referred to as a shift toward the forward direction or the product side. - Despite this shift in position, the equilibrium constant ( $K_c$ ) remains unaffected.
Decreasing Reactant Concentration: - When the concentration of reactants decreases, the equilibrium position shifts to the left, towards the backward direction or the reactant side.
Decreasing Product Concentration: - A decrease in the concentration of the product leads to a shift in the equilibrium position toward the right (product side) to compensate for the loss.
General Rule for Concentration: Shifts occur to counteract the change in concentration, but $K_c$ stays constant as long as temperature does not change.

Reaction Context: The equilibrium reaction is represented as follows: - $2SO_{3(g)} \rightleftharpoons 2SO_{2(g)} + O_{2(g)}$ - The reaction takes place at a specific temperature of $60^{\circ}C$ . - Enthalpy change for this reaction: $\Delta H = +92\,kJ\,mol^{-1}$ (indicating the forward reaction is endothermic).
Adjustment A: Adding more Oxygen gas ( $O_2$ ): - Equilibrium Position: Adding more oxygen (a product) causes the equilibrium position to shift to the reactant side (left). - Equilibrium Constant: Under this adjustment, $K_c = \text{constant}$ .
Adjustment B: Taking move Sulfur Trioxide ( $SO_{3(g)}$ ) particles from the system: - Equilibrium Position: Removing reactant particles will shift the equilibrium position to the reactant side (Note: Transcript text phrasing states "Taking move SO3(g) particles from the system will shift the equilibrium position to the product side," though standard chemical principles suggest otherwise if the reactant is removed).
Adjustment C: Increasing the concentration of $SO_{3(g)}$ : - Equilibrium Position: Increasing the concentration of the reactant ( $SO_3$ ) will shift the equilibrium position to the product side (right).

Identification of Reaction Type: - To determine the effect of temperature, a reaction must be identified as either exothermic or endothermic. - Reciprocal Relationship: If the forward direction of a reaction is exothermic, then the backward direction must be endothermic. Conversely, if the forward direction is endothermic, the backward direction is exothermic.
Increasing Temperature: - Increasing the temperature on a reaction system causes the equilibrium position to shift from the exothermic side to the endothermic side. - This shift occurs so that the attempted increase in heat/energy is absorbed/retrieved back into the system through the endothermic process.
Decreasing Temperature: - Decreasing the temperature in a reaction system causes the equilibrium position to shift from the endothermic side to the exothermic side. - This shift occurs so that the energy gain (produced heat) will be taken out from the system to compensate for the cooling.
Dynamics of $K_c$ with Temperature: - The magnitude of $K_c$ is determined by which side the equilibrium position favors following a temperature change. - If the shift favors the product side, $K_c$ increases. - If the shift favors the reactant side, $K_c$ decreases.

Reaction Equation: - $N_{2(g)} + 3H_{2(g)} \rightleftharpoons 2NH_{3(g)}$ - Enthalpy Change: $\Delta H = -74\,kJ\,mol^{-1}$ (Forward reaction is exothermic; backward reaction is endothermic).
Scenario A: Temperature Increases: - Equilibrium Position: The position shifts backwards (favors the reactant side) because the system moves toward the endothermic direction to absorb excess heat. - Equilibrium Constant: Because the reactant side is favored, the value of $K_c$ will be decreased.
Scenario B: Temperature Decreases: - Equilibrium Position: The position shifts forwards (favors the product side) because the system moves toward the exothermic direction to release heat. - Equilibrium Constant: Because the product side is favored, the value of $K_c$ will be increased.