In which of the following gaseous reaction, the value of Kp will be equal to Kc — Chemical Equilibrium Chemistry Question

💡 Solution & Explanation

# Solution: When $K_p = K_c$ ## Key Relationship The relationship between $K_p$ and $K_c$ is: $$K_p = K_c(RT)^{\Delta n}$$ where $\Delta n = $ (moles of gaseous products) − (moles of gaseous reactants) ## Condition for $K_p = K_c$ For $K_p = K_c$, we need: $$(RT)^{\Delta n} = 1$$ This occurs **only when $\Delta n = 0$** ## What This Means $\Delta n = 0$ requires that the **total number of moles of gaseous products equals the total number of moles of gaseous reactants**. **Example of correct reaction:** $$N_2O_4 \rightleftharpoons 2NO_2$$ - Reactants: 1 mole of gas - Products: 2 moles of gas - $\Delta n = 2 - 1 = 1$ ✗ (Not equal) **Correct example:** $$H_2 + I_2 \rightleftharpoons 2HI$$ - Reactants: 1 + 1 = 2 moles - Products: 2 moles - $\Delta n = 2 - 2 = 0$ ✓ **(Equal)** ## Answer Option **A** must show a reaction where the number of moles of gaseous reactants equals the number of gaseous products ($\Delta n = 0$), making $K_p = K_c$.