JEE · Chemistry · Equilibrium doubts

What does “Dynamic equilibrium” actually mean in Equilibrium, and why does it matter for JEE?

the state where forward and reverse reactions occur at equal rates, so concentrations stay constant.

I keep getting “Dynamic equilibrium” questions wrong in Equilibrium. What's the trap?

thinking the reaction has stopped at equilibrium.

What does “Le Chatelier's principle” actually mean in Equilibrium, and why does it matter for JEE?

if you disturb a system at equilibrium, it shifts to oppose the change.

I keep getting “Le Chatelier's principle” questions wrong in Equilibrium. What's the trap?

predicting the wrong direction of shift.

What does “Equilibrium constant” actually mean in Equilibrium, and why does it matter for JEE?

K compares products to reactants at equilibrium; a large K means products are favoured.

I keep getting “Equilibrium constant” questions wrong in Equilibrium. What's the trap?

including pure solids/liquids in the K expression.

What does “pH scale” actually mean in Equilibrium, and why does it matter for JEE?

pH = −log[H⁺]; below 7 is acidic, above 7 is basic, 7 is neutral at 25°C.

I keep getting “pH scale” questions wrong in Equilibrium. What's the trap?

believing pH can't go below 0 or above 14.

What is the difference between K_c and K_p?

K_c uses molar concentrations; K_p uses partial pressures — they're related by K_p = K_c(RT)^Δn for gases.

What is the difference between strong acid and weak acid?

A strong acid ionises completely (HCl); a weak acid ionises only partly (CH₃COOH) and has an equilibrium.

What is the difference between adding heat to exothermic and adding heat to endothermic?

Heating an exothermic reaction shifts it backward (toward reactants); heating an endothermic one shifts it forward (toward products).

When do I use pH = −log[H⁺] in Equilibrium, and what does it mean?

acidity of a solution.

When do I use K_w = [H⁺][OH⁻] = 10⁻¹⁴ in Equilibrium, and what does it mean?

the ion-product of water at 25°C.