Free Chemical Equilibrium MCQs with Answers
625 Chemical Equilibrium MCQs from Chemistry, each with the correct answer and a written explanation of why it is correct. Free and unlimited, with no account needed.
Reversible reactions reach dynamic equilibrium when forward and reverse rates become equal, and Le Chatelier's principle predicts the effect of changing concentration, pressure or temperature. The chapter also covers solubility product, the common ion effect, buffer action and the conditions used in Haber's process, with equilibrium shifts distinguished from changes in the equilibrium constant.
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625 questions · page 3 of 32
- A. more than 7
- B. less than 7
- C. equal to 7
- D. no effect
Explanation: Adding a base increases the concentration of OH- ions and lowers the concentration of H+ ions, so pH rises above 7 in ordinary aqueous…
Correct answer: more than 7- A. 1 x 10^-1
- B. 1 x 10^-14
- C. 1 x 10^-7
- D. 1
Explanation: Using pH = -log[H+], a pH of 0 gives [H+] = 10^0 mol/L = 1 mol/L. Thus the hydrogen-ion concentration is 1 mol/L.
Correct answer: 1- A. Pt
- B. ZnO + Cr2O3
- C. Fe in fused mixture of Al2O3 + SiQ2 + MgO
- D. All of the above
Explanation: The Haber process uses finely divided iron as the catalyst, with metal oxides acting as promoters to improve its activity and stability.
Correct answer: Fe in fused mixture of Al2O3 + SiQ2 + MgO- A. Kc=x2/(a-x)(b-x)
- B. Kc=x2/v(a-x)
- C. Kc=4×2/(a-2x)2(b-x)
- D. Kc=4x2v2/(a-x)(b-3x)3
Explanation: For N2 + 3H2 ⇌ 2NH3, if the initial amounts are a mol of N2 and b mol of H2, and x mol of N2 reacts in a vessel of volume v dm3, the…
Correct answer: Kc=4x2v2/(a-x)(b-3x)3- A. Fe2O3
- B. V2O5
- C. SO3
- D. Ag2O
Explanation: The Contact Process uses vanadium(V) oxide, V2O5, as the catalyst for oxidising SO2 to SO3.
Correct answer: V2O5- A. volume is decreased
- B. volume increased
- C. heat absorbed
- D. no. of moles of specie decreased
Explanation: When pressure is decreased, a gaseous equilibrium shifts toward the side with more gas molecules because that side occupies a greater…
Correct answer: volume increased- A. Kc is generally greaer than Kp
- B. Kc is generally less than Kp
- C. Kc is generally equal to Kp
- D. Kc is equal to Kp if the total moles of reactants and products are equal
Explanation: The relationship is Kp = Kc(RT)^Δn, where Δn is the difference between gaseous product and reactant coefficients.
Correct answer: Kc is equal to Kp if the total moles of reactants and products are equal- A. Increase of pressure
- B. Increase of volume
- C. Addition of catalyst
- D. Decrease of temperature
Explanation: A catalyst speeds up both the forward and reverse reactions equally, so it does not shift equilibrium or change the equilibrium…
Correct answer: Addition of catalyst- A. 1864
- B. 1866
- C. 1888
- D. None of These
Explanation: Guldberg and Waage proposed the law of mass action in 1864, expressing how the rate or equilibrium composition depends on the active…
Correct answer: 1864- A. Kp > kc
- B. Kc > kp
- C. Kp= kc
- D. Kp ≤ kc
Explanation: For gases, Kp = Kc(RT)^Δn, where Δn = total gaseous product moles - total gaseous reactant moles.
Correct answer: Kp= kc- A. Ka
- B. Kb
- C. Kp
- D. K
Explanation: For gaseous equilibria, an equilibrium constant can be written in terms of partial pressures as Kp rather than concentrations as Kc.
Correct answer: Kp- A. high
- B. low
- C. according to Kc
- D. constant
Explanation: At the beginning of a reaction containing reactants, their concentration is taken as high relative to the products, which may initially be…
Correct answer: high- A. dynamic state
- B. static state
- C. free state
- D. unidirectional state
Explanation: Chemical equilibrium is dynamic because the forward and reverse reactions continue simultaneously at equal rates.
Correct answer: dynamic state- A. PCI5 = PCI3 + Cl2
- B. N2 + 3H2 = 2NH
- C. 2CO + O2 = CO2
- D. N2 + O2 = 2NO
Explanation: Kp and Kc are related by Kp = Kc(RT)^delta n, so they have the same numerical value when the change in gaseous moles, delta n, is zero.
Correct answer: N2 + O2 = 2NO- A. No units
- B. Units
- C. Both A & B
- D. None
Explanation: The units of Kc depend on the change in the total number of moles of gaseous or dissolved species in the balanced equation.
Correct answer: Both A & B- A. reactants
- B. acid
- C. base
- D. catalyst
Explanation: A catalyst lowers the activation energy of both the forward and reverse reactions, increasing both rates and allowing equilibrium to be…
Correct answer: catalyst- A. moles2dm+6
- B. moles-2dm+6
- C. moles+2dm-6
- D. Kc may or may not have units
Explanation: For a reaction such as N2 + 3H2 ⇌ 2NH3, delta n = 2 - 4 = -2, so Kc has units of (mol dm-3)^-2 = dm6 mol-2.
Correct answer: Kc may or may not have units- A. reversible
- B. irreversible
- C. spontaneous
- D. non-spontaneous
Explanation: A reversible reaction can proceed in both the forward and backward directions, so reactants form products while products can reform…
Correct answer: reversible- A. Kc is constant at given temperature
- B. Kc is unaffected by change in concentration of reactants or products
- C. Kc indicates the extent of reaction but not about the rate of reaction.
- D. All of the above
Explanation: At a fixed temperature, Kc has a constant value and does not change when equilibrium concentrations are disturbed, although the…
Correct answer: All of the above- A. whole amount of reactant does not change into product
- B. chemical equilibrium is established
- C. a catalyst changes the direction of reaction
- D. rate of forward reaction decreases as reaction proceeds
Explanation: A catalyst does not change the direction or position of equilibrium; it lowers the activation energy for both forward and reverse…
Correct answer: a catalyst changes the direction of reaction