Unit-9 Chemical Equilibrium
Explore subjects and practice MCQs
19
Topics
1,900
Total MCQs
Unit-9 Chemical Equilibrium
Answer: The Contact process manufactures sulphuric acid by oxidizing SO2 to SO3 and dissolving it in water.
Answer: Le Chatelier's principle says the system responds by shifting equilibrium to counteract the applied stress.
Answer: The law of mass action states that the rate of reaction is proportional to the product of the molar concentrations (active masses) of the reactants.
Answer: The forward reaction has fewer gas moles (4 → 2), so high pressure shifts equilibrium towards more ammonia formation.
Answer: A catalyst lowers the activation energy for both directions equally, so equilibrium is reached faster without changing its position.
Answer: Equilibrium is dynamic because forward and reverse reactions continue to occur at equal rates at the molecular level.
Answer: Kc equals the concentration of products raised to their coefficients divided by the concentration of reactants raised to their coefficients.
Answer: The double arrow (⇌) indicates that the reaction proceeds in both forward and reverse directions.
Answer: Kc is temperature dependent, so changing temperature changes its value for the reaction.
Answer: Lowering pressure favours the side with more gas molecules (reactants side, 4 moles), so the equilibrium shifts backward.
Answer: The forward reaction of the Haber process converts nitrogen and hydrogen into ammonia.
Answer: Pure solids like CaCO3 and CaO are omitted from the expression, leaving Kc = [CO2].
Answer: Once equilibrium is reached, the concentrations of all species become constant because the rates of forward and reverse reactions are equal.
Answer: Although a lower temperature favours more ammonia, the rate becomes too slow, so a moderate temperature gives an acceptable balance of rate and yield.
Answer: A catalyst does not shift the position of equilibrium; it only helps reach equilibrium faster.
Answer: Vanadium pentoxide (V2O5) is used as the catalyst to speed up the oxidation of SO2 to SO3 in the Contact process.
Answer: A small Kc means the concentration of reactants is much greater than that of products, so reactants are favoured.
Answer: Irreversible reactions proceed in one direction and go to completion, so products do not reform the reactants.
Answer: Since the forward reaction (4 moles to 2 moles) decreases gas moles, high pressure shifts equilibrium towards more ammonia.
Answer: Heat acts like a reactant in an endothermic reaction, so adding heat shifts equilibrium forward and increases Kc.