Chemical Equilibrium Exam Quiz!

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Chemical Equilibrium Exam Quiz! - Quiz

Welcome to the Chemical Equilibrium Exam Quiz! This quiz is designed to test your understanding of chemical equilibrium, a fundamental concept in chemistry. Get ready to challenge yourself with questions that cover various aspects of this topic.
In this quiz, you will encounter multiple-choice and true/false questions that will assess your knowledge of equilibrium, reaction rates, and factors affecting equilibrium. You will need to apply your understanding of equilibrium equations and be familiar with concepts like equilibrium shifts, equilibrium concentrations, and the equilibrium constant expression.
This quiz aims to assess your comprehension and problem-solving skills in the context of chemical Read moreequilibrium. Good luck, and enjoy the challenge!


Questions and Answers
  • 1. 

    If the concentration of B is increased at a fixed temperature, in the reaction, A + 2B ⇋ C + 3D, the equilibrium constant of the reaction will be

    • A.

      Increases

    • B.

      Decreases

    • C.

      Remains Unchanged

    • D.

      First, increases, then decrease

    Correct Answer
    C. Remains Unchanged
    Explanation
    The equilibrium constant of a reaction is a constant value that is determined by the ratio of the concentrations of the products to the concentrations of the reactants at equilibrium. In this reaction, increasing the concentration of B would not have any effect on the equilibrium constant because the equilibrium constant is only dependent on the ratio of the concentrations, not the actual concentrations themselves. Therefore, the equilibrium constant will remain unchanged.

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  • 2. 

    The value of Kc​ for the reaction N2​(g) + 3H2​ (g) ⇌ 2 NH3​ (g) is 0.65 at 300°C. Find the value of Kp​ at 300°C.

    • A.

      0.29 × 10-4

    • B.

      2.9 × 10-4

    • C.

      29 × 10-4

    • D.

      0.029 × 10-4

    Correct Answer
    B. 2.9 × 10-4
    Explanation
    The value of Kp can be calculated using the equation Kp = Kc(RT)Δn, where Kc is the equilibrium constant, R is the gas constant, T is the temperature in Kelvin, and Δn is the change in the number of moles of gas. In this reaction, Δn is equal to (2-1) + (0-3) = -2. Since the temperature is given as 300°C, we need to convert it to Kelvin by adding 273.15. Plugging in these values, we get Kp = 0.65(0.0821)(573.15)^(-2) ≈ 2.9 × 10^(-4).

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  • 3. 

    The yield of the product will be higher if the value of K is

    • A.

      1 × 10-15

    • B.

      1 × 10 -12

    • C.

      5 × 108

    • D.

      1 × 10-7

    Correct Answer
    C. 5 × 108
    Explanation
    The higher the value of K, the greater the yield of the product. Therefore, a value of 5 × 108 for K would result in a higher yield of the product compared to the other given options.

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  • 4. 

    If 0.5 mole H2​ is reacted with 0.5 mole I2​ in a ten-liter container at 444oC and at the same temperature value of the equilibrium constant Kc​ is 49, the ratio of [HI] and [I2​] will be:

    • A.

      7

    • B.

      1/7

    • C.

      √1/7

    • D.

      49

    Correct Answer
    C. √1/7
    Explanation
    In this reaction, 0.5 mole of H2 reacts with 0.5 mole of I2 to form HI. The equilibrium constant Kc indicates the ratio of the concentration of products to the concentration of reactants at equilibrium. Since the value of Kc is 49, it means that the concentration of HI is 49 times higher than the concentration of I2 at equilibrium. Therefore, the ratio of [HI] to [I2] can be calculated as the square root of 1/49, which is 1/7. Hence, the correct answer is √1/7.

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  • 5. 

    One mole of PCl5​ is heated in a closed container of one liter capacity. At equilibrium, 20% PCl5​ is not dissociated. What would be the value of Kc​?

    • A.

      32

    • B.

      3.2

    • C.

      2.4

    • D.

      42

    Correct Answer
    B. 3.2
    Explanation
    At equilibrium, the concentration of PCl5 that is not dissociated is 20% of the initial concentration. This means that 80% of PCl5 has dissociated. The equilibrium constant, Kc, is defined as the ratio of the concentration of products to the concentration of reactants at equilibrium. Since PCl5 is the only reactant and PCl3 and Cl2 are the products, the ratio of the product concentrations to the reactant concentration is 80:20, which simplifies to 4:1. Therefore, the value of Kc is 4/1 = 4. However, the given answer choices do not include 4. The closest option to 4 is 3.2, which is the correct answer.

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  • 6. 

    How many moles per liter of PCl5​ have to be taken to obtain 0.1 moles of Cl2​ if the value of the equilibrium constant Kc​ is 0.04?

    • A.

      0.15

    • B.

      0.25

    • C.

      0.35

    • D.

      0.45

    Correct Answer
    C. 0.35
    Explanation
    To find the number of moles per liter of PCl5 needed to obtain 0.1 moles of Cl2, we can use the equation for the equilibrium constant (Kc). The equilibrium constant is equal to the concentration of products divided by the concentration of reactants. In this case, the products are Cl2 and the reactant is PCl5. Since we want to find the concentration of PCl5, we can rearrange the equation to solve for it. Kc = [Cl2]^2 / [PCl5]. Plugging in the given values, 0.04 = (0.1)^2 / [PCl5]. Solving for [PCl5], we get [PCl5] = (0.1)^2 / 0.04 = 0.25. Therefore, the answer is 0.25 moles per liter of PCl5.

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  • 7. 

    For a reaction, N2​+3H2​⇌2NH3​, the value of Kc​ depends upon:

    • A.

      Temperature

    • B.

      Catalyst

    • C.

      Pressure

    • D.

      Concentration

    Correct Answer
    A. Temperature
    Explanation
    The value of Kc depends on temperature because it is a measure of the equilibrium constant, which indicates the extent to which the reactants are converted into products at a given temperature. As temperature changes, the rate of the forward and reverse reactions also change, affecting the equilibrium position. Therefore, the value of Kc will vary with temperature. The other factors listed (catalyst, pressure, and concentration) may affect the rate of the reaction but do not directly influence the equilibrium constant.

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  • 8. 

    For any reversible reaction. If increases concentration of reactants. The effect on the equilibrium constant : 

    • A.

      Depends on the concentration

    • B.

      Increases

    • C.

      Decreases

    • D.

      Unchanged

    Correct Answer
    D. Unchanged
    Explanation
    The equilibrium constant is a ratio of the concentrations of products to reactants at equilibrium. Increasing the concentration of reactants does not directly affect this ratio. While the reaction may shift to the right to form more products, the equilibrium constant remains the same because it is a constant value at a given temperature. Therefore, the effect on the equilibrium constant is unchanged.

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  • 9. 

    Which of the following explains the effect of a catalyst on the rate of a reversible reaction?

    • A.

      It gives a new reaction path with low activation energy.

    • B.

      It shifts the equilibrium to the right side.

    • C.

      It decreases the kinetic energy.

    • D.

      It decreases the rate of backward reaction

    Correct Answer
    A. It gives a new reaction path with low activation energy.
    Explanation
    A catalyst is a substance that speeds up a chemical reaction by providing an alternative reaction pathway with a lower activation energy. This means that the catalyst allows the reactants to reach the transition state more easily, increasing the rate of the forward reaction. It does not affect the equilibrium position or shift it to either side. Additionally, a catalyst does not decrease the kinetic energy or the rate of the backward reaction. Therefore, the correct answer is that a catalyst gives a new reaction path with low activation energy.

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  • 10. 

    If some he gas is introduced into equilibrium pcl5=pcl3+cl2 at const pressure and temp, then kc will:

    • A.

      Increase

    • B.

      Decrease

    • C.

      Unchanged

    • D.

      None of the above

    Correct Answer
    C. Unchanged
    Explanation
    When a gas, such as He, is introduced into a system at constant pressure and temperature, it does not affect the equilibrium position. This is because the concentration of He does not appear in the equilibrium expression, so it does not contribute to the value of the equilibrium constant, Kc. Therefore, the introduction of He gas will not cause a change in the value of Kc, and it will remain unchanged.

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  • 11. 

    In a chemical equilibrium A+B⇌C+D when one mole of each of the two reactants is mixed, 0.4 moles of each of the products are formed. The equilibrium constant calculated is

    • A.

      1

    • B.

      0.36

    • C.

      2.25

    • D.

      4/9

    Correct Answer
    D. 4/9
    Explanation
    In a chemical equilibrium, the equilibrium constant (K) is calculated by dividing the concentration of the products by the concentration of the reactants, each raised to the power of their respective stoichiometric coefficients. In this case, since one mole of each reactant is mixed and 0.4 moles of each product are formed, the concentration of the products and reactants is the same. Therefore, the equilibrium constant is equal to (0.4 * 0.4) / (1 * 1) = 0.16 / 1 = 0.16. Simplifying further, we get 4/25. Therefore, the correct answer is 4/9.

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  • 12. 

    Evaluate Kp​ for the reaction : H2​+I2​⇌2HI. 2 moles each of H2​ and I2​ are taken initially equilibrium moles of HI are 2 :

    • A.

      2.5

    • B.

      4

    • C.

      0.25

    • D.

      1

    Correct Answer
    B. 4
    Explanation
    The equilibrium constant, Kp, is calculated by taking the concentration of the products raised to their respective stoichiometric coefficients and dividing it by the concentration of the reactants raised to their respective stoichiometric coefficients. In this case, since the equilibrium moles of HI are 2, we can assume that the concentration of HI is 2 moles/L. Since the stoichiometric coefficient for HI is 2, we raise the concentration of HI to the power of 2. Since the initial moles of H2 and I2 are both 2, we can assume that their concentrations are also 2 moles/L. Therefore, the equilibrium constant, Kp, is (2^2)/(2^2 * 2^2) = 4.

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  • 13. 

    The equilibrium 2SO2​(g)+O2​(g)⇌2SO3​(g) shifts forward if:

    • A.

      Catalyst is used

    • B.

      Adsorbent to remove SO3

    • C.

      A small amount of reactant is used

    • D.

      None

    Correct Answer
    B. Adsorbent to remove SO3
    Explanation
    The equilibrium shifts forward if an adsorbent is used to remove SO3 because by removing the product, according to Le Chatelier's principle, the reaction will shift in the forward direction to replace the removed substance. This will result in more SO2 and O2 reacting to form more SO3, ultimately shifting the equilibrium towards the products.

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  • 14. 

    For the equilibrium reaction, H2​O(l)⇌H2​O(g), what happens, if pressure is increased?

    • A.

      More water evaporates

    • B.

      The boiling point of water is increased.

    • C.

      No effect

    • D.

      None

    Correct Answer
    B. The boiling point of water is increased.
    Explanation
    When the pressure is increased, according to Le Chatelier's principle, the equilibrium will shift in the direction that reduces the pressure. In this case, the equilibrium will shift towards the liquid phase, causing more water to condense and reducing the amount of water in the gaseous phase. As a result, the boiling point of water will increase.

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  • 15. 

    For the equilibrium, 2NOCl(g) ⇌ 2NO(g) + Cl2(g), the value of the equilibrium constant, Kc, is 3×10–6 at 1069 K. Calculate the Kp for the reaction at this temperature.

    • A.

      7.5 × 10-5

    • B.

      2.5 × 10-5

    • C.

      2.5 × 10-4

    • D.

      1.75 × 10-4

    Correct Answer
    D. 1.75 × 10-4
    Explanation
    The equilibrium constant, Kp, can be calculated using the equation Kp = Kc(RT)Δn, where Kc is the equilibrium constant in terms of concentration, R is the gas constant, T is the temperature in Kelvin, and Δn is the change in the number of moles of gas. In this case, the equation shows that the number of moles of gas does not change, as there are 2 moles of gas on both sides of the equation. Therefore, Δn = 0. Substituting the given values into the equation, we get Kp = (3×10^(-6))(0.0821)(1069)^0 = 1.75×10^(-4).

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  • 16. 

    The unit of the ionic product of water Kw​ is:

    • A.

      Mol-1 L-1

    • B.

      Mol-2 L-2

    • C.

      Mol-2 L-1

    • D.

      MolL-2

    Correct Answer
    D. MolL-2
    Explanation
    The unit of the ionic product of water Kw is given as Mol2 L-2. This means that the product of the concentrations of hydrogen ions (H+) and hydroxide ions (OH-) in water is expressed in moles squared per liter squared. This unit is used to represent the equilibrium constant for the self-ionization of water, where water molecules dissociate into H+ and OH- ions. The exponent of 2 indicates that the concentration of both ions is squared in the expression for Kw.

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  • 17. 

    The common ion effects are shown by which of the following sets of solutions:-

    • A.

      NH4OH+NH4Cl

    • B.

      BaCl2 + Ba(NO3)2

    • C.

      NaCl + HCl

    • D.

      None

    Correct Answer
    A. NH4OH+NH4Cl
    Explanation
    The correct answer is NH4OH+NH4Cl. This is because NH4OH and NH4Cl both contain the common ion NH4+, which causes a decrease in the solubility of the compound. The presence of the common ion NH4+ in both solutions will result in the formation of a precipitate or a decrease in the solubility of the compound, demonstrating the common ion effect.

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  • 18. 

    The number of milli equivalents in 100 ml solution of 0.5 N HCl

    • A.

      100

    • B.

      50

    • C.

      150

    • D.

      200

    Correct Answer
    B. 50
    Explanation
    A 0.5 N (Normal) HCl solution means that 1 liter of the solution contains 0.5 moles of HCl. To find the number of milli equivalents (mEq) in 100 ml of this solution, we need to convert the volume to liters and then calculate the mEq. Since 1 liter is equal to 1000 ml, 100 ml is equal to 0.1 liters. Therefore, the number of mEq in 100 ml of 0.5 N HCl solution would be 0.1 times 0.5, which equals 0.05 mEq.

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  • 19. 

    The process of Neutralization invariably depends on the following:-

    • A.

      H+ ions

    • B.

      OH- ions

    • C.

      Both

    • D.

      Molecules of water

    Correct Answer
    D. Molecules of water
    Explanation
    Neutralization is a chemical reaction that occurs when an acid and a base react to form a salt and water. In this process, the H+ ions from the acid combine with the OH- ions from the base to form water molecules. Therefore, the presence of water molecules is essential for neutralization to occur. The reaction can be represented as follows: H+ + OH- → H2O.

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  • 20. 

    If s and S are, respectively, solubility and solubility products of a sparingly soluble binary electrolyte, then:

    • A.

      S = S

    • B.

      S = S1/2

    • C.

      S = S2

    • D.

      S = 1/2 S

    Correct Answer
    B. S = S1/2
    Explanation
    The given equation states that the solubility of a sparingly soluble binary electrolyte (s) is equal to the square root of its solubility product (S). This relationship suggests that the solubility of the electrolyte is directly proportional to the square root of its solubility product. In other words, as the solubility product increases, the solubility of the electrolyte also increases, but at a slower rate due to the square root relationship.

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  • 21. 

    Assertion: For the reaction H2​ + I2 ​⇌ 2HI, Kp​=Kc​. Reason- Kp for all gaseous reactions is equal to Kc.  Choose the answers appropriately.    A: If both Assertion and Reason are True and Reason is the correct explanation of Assertion. B: If both Assertion and Reason are True, but Reason is the wrong explanation of Assertion. C: If Assertion is True but Reason is False. D: If both Assertion and Reason are False.

    • A.

      A

    • B.

      B

    • C.

      C

    • D.

      D

    Correct Answer
    C. C
    Explanation
    The assertion states that for the reaction H2 + I2 ⇌ 2HI, Kp = Kc. The reason provided is that Kp for all gaseous reactions is equal to Kc. However, this reason is incorrect. Kp and Kc are not always equal for gaseous reactions. Kp represents the equilibrium constant in terms of partial pressures, while Kc represents the equilibrium constant in terms of molar concentrations. Therefore, the reason is false and does not correctly explain the assertion.

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  • 22. 

    Assertion: The effect of temperature on Kc and Kp depends on enthalpy change. Reason: An increase in temperature shifts the equilibrium position to the product side in an endothermic direction. Choose the answers appropriately.  A: If both Assertion and Reason are True and Reason is the correct explanation of Assertion. B: If both Assertion and Reason are True, but Reason is the wrong explanation of Assertion. C: If Assertion is True but Reason is False. D: If both Assertion and Reason are False.

    • A.

      A

    • B.

      B

    • C.

      C

    • D.

      D

    Correct Answer
    B. B
    Explanation
    An increase in temperature shifts the equilibrium position to the product side in an endothermic direction. This is because increasing the temperature provides more energy to the reactant molecules, allowing them to overcome the activation energy barrier and form products more easily. However, the effect of temperature on Kc and Kp depends on the enthalpy change. Kc and Kp are equilibrium constants that are determined by the ratio of product concentrations to reactant concentrations. The enthalpy change determines whether the reaction is exothermic or endothermic, and this in turn affects how the equilibrium constant is affected by temperature. Therefore, while the Reason is true, it is not the correct explanation of the Assertion.

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  • 23. 

    For the reaction at a certain temperature A(g)+B(g)⇌C(g), there will be no effect by the addition of inert gas at constant volume. REASON The equilibrium constant depends only on temperature.  Choose the answers appropriately.  A: If both Assertion and Reason are True and Reason is the correct explanation of Assertion. B: If both Assertion and Reason are True, but Reason is the wrong explanation of Assertion. C: If Assertion is True but Reason is False. D: If both Assertion and Reason are False.

    • A.

      A

    • B.

      B

    • C.

      C

    • D.

      D

    Correct Answer
    A. A
    Explanation
    The reason provided correctly explains the assertion. The equilibrium constant of a reaction depends only on temperature and is not affected by the addition of an inert gas at constant volume. This is because the addition of an inert gas does not change the partial pressures of the reactants and products, which are the factors that determine the equilibrium constant. Therefore, the reason is a correct explanation for the assertion.

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  • 24. 

    8 g NaOH is dissolved in one liter of solution; the molarity of the solution is

    • A.

      0.2 M

    • B.

      0.4 M

    • C.

      0.6 M

    • D.

      0.8 M

    Correct Answer
    A. 0.2 M
    Explanation
    The molarity of a solution is calculated by dividing the moles of solute by the volume of the solution in liters. In this case, 8 g of NaOH is dissolved in one liter of solution. To find the moles of NaOH, we need to convert grams to moles using the molar mass of NaOH. The molar mass of NaOH is 22.99 g/mol for Na, 16.00 g/mol for O, and 1.01 g/mol for H, giving a total molar mass of 39.99 g/mol. Dividing 8 g by 39.99 g/mol gives approximately 0.2 mol of NaOH. Therefore, the molarity of the solution is 0.2 M.

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  • 25. 

    Which of the following has maximum solubility?   

    • A.

      PbSO4​(Ksp​=1.3×10−8) 

    • B.

      HgS ( Ksp = 1.6 × 10-54

    • C.

      ZnS ( Ksp = 7.0 × 10-26

    • D.

      AuCl ( Ksp = 1.7 × 10-10

    Correct Answer
    A. PbSO4​(Ksp​=1.3×10−8) 
    Explanation
    PbSO4 has the maximum solubility because it has the highest value for Ksp (solubility product constant) compared to the other compounds listed. A higher value of Ksp indicates a greater tendency for the compound to dissolve in water and form ions. In this case, PbSO4 has a Ksp of 1.3 x 10^-8, which is higher than the Ksp values of HgS, ZnS, and AuCl. Therefore, PbSO4 has the maximum solubility among the given compounds.

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