What is/are true about equilibrium state? — Chemical Equilibrium Chemistry Question

💡 Solution & Explanation

Step 1 - Analyze Statement (A): Effect of a Catalyst on the Equilibrium State A catalyst provides an alternative reaction pathway with lower activation energy. It decreases $E_a$ for both the forward and backward reactions by the same amount: \[\Delta E_{a,f} = \Delta E_{a,b}\] Both $k_f$ and $k_b$ increase by the same factor, so the catalyst helps reach equilibrium faster but does not alter the equilibrium position or the ratio of concentrations. **Statement (A) is correct.** Step 2 - Analyze Statement (B): Independence of Equilibrium Constant from Initial Concentrations The equilibrium constant $K_c$ is a thermodynamic property that depends only on temperature. If initial concentrations of reactants change, the system shifts to different individual equilibrium concentrations, but the ratio defined by $K_c$ remains unchanged. **Statement (B) is correct.** Step 3 - Analyze Statement (C): Dynamic Nature of Chemical Equilibrium Chemical equilibrium is dynamic, not static. At equilibrium: \[r_f = r_b \neq 0\] Both forward and backward reactions continue simultaneously at equal rates. Macroscopic properties appear unchanged, but the reaction never ceases. **Statement (C) is incorrect.** Step 4 - Analyze Statement (D): Equilibrium Constant Independence from Pressure The equilibrium constant is linked to the standard Gibbs free energy change: \[\Delta_r G^\circ = -RT \ln K\] Since $\Delta_r G^\circ$ is defined at a fixed reference pressure and depends only on temperature, $K$ is independent of the total pressure. Pressure may shift the equilibrium position (Le Chatelier's principle) but does not change the value of $K$. **Statement (D) is correct.** \[\text{Correct Options: } \boxed{\text{A, B, D}}\]