Unit-9 Chemical Equilibrium
Explore subjects and practice MCQs
19
Topics
1,900
Total MCQs
Unit-9 Chemical Equilibrium
Answer: Active mass or molar concentration is expressed in moles per litre (mol/dm3), which is used in equilibrium constant expressions.
Answer: Since CaCO3 and CaO are pure solids, they are omitted, leaving Kc equal to the concentration of CO2 gas only.
Answer: The double arrow indicates that both forward and reverse reactions proceed simultaneously until equilibrium is reached.
Answer: The product side has fewer gas moles (3 → 2), so increasing pressure shifts the equilibrium towards SO3.
Answer: Reducing pressure favours the side with more gas moles (the reactant side), shifting equilibrium towards SO2 and O2.
Answer: The Haber reaction N2 + 3H2 ⇌ 2NH3 is reversible, so equilibrium is established under suitable conditions.
Answer: Kc = [NH3]^2 divided by [N2] times [H2]^3, using the coefficients as exponents.
Answer: The Haber process manufactures ammonia by reacting nitrogen with hydrogen under high pressure and moderate temperature.
Answer: Decreasing volume increases pressure, and the equilibrium shifts towards the side with fewer gas moles, which is the forward (NH3) side.
Answer: The number of gas moles is the same on both sides (2 = 2), so pressure has no effect on the equilibrium position.
Answer: A catalyst affects only the rate of reaching equilibrium, not the position of equilibrium itself.
Answer: Since the forward reaction is exothermic, too high a temperature shifts equilibrium towards reactants and lowers ammonia yield.
Answer: Equilibrium is dynamic because the reactions continue in both directions at equal rates even though there is no net change.
Answer: Concentration, temperature, and pressure changes all disturb equilibrium, which then shifts according to Le Chatelier's principle.
Answer: Raising the temperature shifts an exothermic equilibrium towards the reactants, which lowers the value of Kc.
Answer: Dynamic equilibrium means both reactions are continuously occurring but at equal rates, giving constant concentrations.
Answer: A catalyst speeds up both the forward and reverse reactions equally, so it only shortens the time to reach equilibrium.
Answer: Chemical equilibrium is dynamic: forward and reverse reactions continue at equal rates in a closed system.
Answer: Adding a reactant shifts the equilibrium towards the products, increasing the amount of SO3 formed.
Answer: Reversing a reaction inverts the equilibrium constant, so the new Kc is the reciprocal of the original value.