Q. For a reaction with a rate constant of 0.02 M⁻¹s⁻¹ and initial concentration of 0.5 M, what is the time taken to reach 0.25 M in a second-order reaction? (2023)
A.25 s
B.50 s
C.10 s
D.20 s
Solution
Using t = 1 / (k[A₀]) * (1/[A] - 1/[A₀]), t = 1 / (0.02 * 0.5) * (1/0.25 - 1/0.5) = 25 s.
Q. For the exothermic reaction A + B ⇌ C + heat, what will happen if the temperature is increased? (2020)
A.Equilibrium will shift to the right
B.Equilibrium will shift to the left
C.No change in equilibrium
D.Equilibrium will shift to the center
Solution
For an exothermic reaction, increasing the temperature shifts the equilibrium to the left, favoring the reactants, as the system tries to absorb the added heat.
Correct Answer: B — Equilibrium will shift to the left
Q. For the reaction 2SO2(g) + O2(g) ⇌ 2SO3(g), what will happen if the volume of the container is increased? (2020) 2020
A.Equilibrium shifts to the right
B.Equilibrium shifts to the left
C.No change in equilibrium
D.Reaction stops
Solution
Increasing the volume decreases the pressure, and according to Le Chatelier's principle, the equilibrium will shift to the side with more moles of gas, which is the left side in this case.
Correct Answer: B — Equilibrium shifts to the left
Q. For the reaction N2(g) + 3H2(g) ⇌ 2NH3(g), what happens to the equilibrium if the volume of the container is decreased? (2020)
A.Equilibrium shifts to the right
B.Equilibrium shifts to the left
C.No change in equilibrium
D.Equilibrium shifts to the side with more moles
Solution
Decreasing the volume increases the pressure, and according to Le Chatelier's principle, the equilibrium will shift to the side with fewer moles of gas, which is the right side in this case.
Correct Answer: A — Equilibrium shifts to the right
Q. For the reaction: 2SO2(g) + O2(g) ⇌ 2SO3(g), what happens to the equilibrium position if the volume of the container is decreased? (2020)
A.Shifts to the left
B.Shifts to the right
C.No change
D.Depends on temperature
Solution
Decreasing the volume increases the pressure, and according to Le Chatelier's principle, the equilibrium will shift towards the side with fewer moles of gas, which is the right side in this case.
Q. For the reaction: 2SO2(g) + O2(g) ⇌ 2SO3(g), what will happen if the volume of the container is increased? (2020)
A.Equilibrium shifts to the right
B.Equilibrium shifts to the left
C.No change in equilibrium
D.Equilibrium shifts to the center
Solution
Increasing the volume decreases the pressure, and according to Le Chatelier's principle, the equilibrium will shift to the side with more moles of gas, which is the left side in this case.
Correct Answer: B — Equilibrium shifts to the left
