Kerala KEAM 5 June 2024 Solved Paper

The equilibrium constant expressions $K_P$ and $K_C$ relate to pressure and concentration respectively, and they are equal only for reactions where the total number of moles of gas does not change.- $K_P$ is used when dealing with partial pressures, and $K_C$ is used when dealing with concentrations.- $K_P$ and $K_C$ will be equal when the change in the number of moles of gases on both sides of the reaction is zero.Let’s examine the options:- (A) The reaction $N_2(g) + 3H_2(g) \rightleftharpoons 2NH_3(g)$ involves 4 moles of gas on the left and 2 moles of gas on the right, so $K_P \neq K_C$.- (B) The reaction $2SO_2(g) + O_2(g) \rightleftharpoons 2SO_3(g)$ involves 3 moles of gas on the left and 2 moles of gas on the right, so $K_P \neq K_C$.- (C) The reaction $N_2O_4(g) \rightleftharpoons 2NO_2(g)$ involves 1 mole of gas on the left and 2 moles of gas on the right, so $K_P \neq K_C$.- (D) The reaction $PCl_5(g) \rightleftharpoons PCl_3(g) + Cl_2(g)$ involves 1 mole of gas on the left and 2 moles of gas on the right, so $K_P \neq K_C$.- (E) The reaction $H_2(g) + Br_2(g) \rightleftharpoons 2HBr(g)$ involves 2 moles of gas on the left and 2 moles of gas on the right, so $K_P = K_C$.Thus, the correct answer is (E). Quick Tip: For the equilibrium constant expressions $K_P$ and $K_C$ to be equal, the number of moles of gaseous reactants must equal the number of moles of gaseous products. When this happens, $K_P = K_C$.