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All questions of Chemical Equilibrium for Chemistry Exam

Can you explain the answer of this question below:

Under the equilibrium condition for the reaction,  the total pressure is 12 atm. The value of Kp is:

  • A:

    16

  • B:

    0.5

  • C:

    2

  • D:

    32

The answer is a.

If 50% of CO2 reacts: C(s) + CO2(g) --> 2CO(g) P(total) = 12 atm If half the CO2 reacted then CO2 is x/2 and CO is x, and Pt = 12. Then x/2 + x = 12 1.5x = 12 x = 8 P(CO2) = 4 atm P(CO) = 8 atm The initial pressure of CO2 is 8 atm. When half of it reacts then 4 atm is left and the pressure of CO is twice as great, which is 8 atm. Kp = P(CO)^2 / P(CO2) Kp = 8^2 / 4 Kp = 16

For the following gaseous phase equilibrium,

Kp is found to be equal to Kx (Kx is equilibrium constant when concentration are taken in terms of mole fraction. This is attained when pressure is 
  • a)
    1 atm
  • b)
    0.5 atm
  • c)
    2 atm
  • d)
    4 atm
Correct answer is option 'A'. Can you explain this answer?

Preeti Iyer answered
The correct answer is Option A.
Kp = Equilibrium constant in terms of partial pressure
Kc = Equilibrium constant in terms of concentration
Kx = Equilibrium constant in terms of mole fraction
             Kp = KcRTΔn ---(1)
           Kp = K * (Pt)Δn ---(2)
a)   1 atm
Given PCl5 (g) ---> PCl3 (g) + Cl2 (g)
  Δn = 2 – 1
Given Kp = Kx  
From (2)
          Kp = Kx when PT = 1

Consider the following gaseous equilibria given below
The equilibrium constant for the reaction, in terms of K1, K2 and K3 will be
  • a)
    K1K2K3
  • b)
  • c)
  • d)
Correct answer is option 'D'. Can you explain this answer?

Veda Institute answered
Correct Answer :- d
Explanation : K1 = [NH3]2/[N2] [H2]3
K2 = [NO]2/[N2] [O2]3
K3 = [H2O]/[O2]1/2 [H2]
For the reaction :
K = {[NO]2 [H2O]3}/{[NH3]2 [O2]3/2}
= (K2 K33)/K1

pH of a saturated solution of Ba(OH)2 is 12. The value of solubility product (Ksp) of Ba(OH)2 is
  • a)
    4.0 × 10–6
  • b)
    5.0 × 10–6
  • c)
    3.3 × 10–7
  • d)
    5.0 × 10–7
Correct answer is option 'D'. Can you explain this answer?

Sagarika Patel answered
pH + pOH = 14
pOH = 14 -12 =2 (given pH =12)
pOH = -log[OH-]
[OH-] = 10-pOH= 10-2....1
Ba(OH)2---> Ba+2+ 2OH-
At equilibrium:Ba+2= x andOH-= 2x
since 2x =10-2as eq. 1
therefore x = 10-2/2 = 0.5 * 10-2
ksp= [Ba+2]*[OH-]2= [0.5* 10-2][10-2]2= 0.5 *10-6=5 *10-7

The concentration of the oxides of nitrogen are monitored in air-pollution reports. At 25°C, the equilibrium constant for the reaction,

 is 1.3 x 106 and that for 

is 6.5 x 10-16 (when each species is expressed in terms of partial pressure).
For the reaction,

equilibrium constant is
  • a)
  • b)
  • c)
  • d)
Correct answer is option 'A'. Can you explain this answer?

Crafty Classes answered
Given equations are 
NO (g) + ½ O2 (g) ⇌ NO2 (g) ----------(i) k1 = 1.3×106
And ½ N2 (g) + ½ O2 (g)     ⇌     NO(g) ----------(ii) k2 = 6.5×10-16
To get the reaction, N2(g) + 2O2(g) ⇌ 2NO2(g) ----------(iii) k3
We multiply eqn (i) and eqn (ii) by 2 and adding both reaction, we get eqn (iii)
k3 = k12×k22
    = (1.3×106)2×(6.5×10-16)2
    = 1.69×1012×42.25×10-32
    = 7.14×10-19

For the reaction, 
if Kp = Kc (RT)X, when the symbols have usual meaning, the value of x is (assuming ideality)
[jee Main 2014]
  • a)
    -1
  • b)
    -1/2
  • c)
    +1/2
  • d)
    +1
Correct answer is option 'B'. Can you explain this answer?

Gaurav Kumar answered
The correct answer is Option B.
SO2(g) + 1/2O2(g) ⇌ SO3(g)
KP = KC(RT)Δn
Δn= no. of gaseous moles of product minus no. of gaseous moles of reactant
Δn = 1−1−1/2
∴Δn = −1/2
 

For the reaction:
At a given temperature, the equilibrium amount of CO2(g) can be increased by.
  • a)
    Adding a suitable catalyst
  • b)
    Adding an inert gas
  • c)
    Decreasing the volume of the container
  • d)
    Increasing the amount of CO(g)
Correct answer is option 'D'. Can you explain this answer?

Bhawesh answered
According to the Le chatlier principle if a constraint (such as a change in pressure, temperature, or concentration of a reactant) is applied to a system in equilibrium, the equilibrium will shift so as to tend to counteract the effect of the constraint. Here if we increase the concentration of CO more CO2 will be formed.

A 2 L vessel containing 2g of H2 gas at 27°C is connected to a 2L vessel containing 176 g of CO2 gas at 27°C. Assuming ideal behaviour of H2 and CO2, the partial pressure of H2 at equilibrium is………bar.
    Correct answer is '6.25'. Can you explain this answer?

    Raghav Rane answered
    H2 + CO2 - mixture of non-reacting gases
    2g H2 = 1 mol
    176g CO2 = 4 mol
    Total no. of moles = 5
    Total volume = 2+2 = 4L
    Temperature = 27+273 = 300K
    Total pressure, P=nRT/V=(5*0.083*300/4)= 31.125 bar
    According to Dalton's law, p1 = P*(x1)
    Mole fraction of H2=1/(1+4)=1/5
    Therefore, p(H2)= 31.125*0.2 = 6.225 bar
     

    Direction (Q. Nos. 21) Choice the correct combination of elements and column I and coloumn II  are given as option (a), (b), (c) and (d), out of which ONE option is correct.
    The progress of the reaction  with time t is shown below.


    Match the parameters in Column l with their respective values in Column II.


    Codes
          
    • a)
      a
    • b)
      b
    • c)
      c
    • d)
      d
    Correct answer is option 'A'. Can you explain this answer?

    Rajesh Gupta answered
    The correct answer is Option A.
    Loss in concentration of A in I hour = = 0.1
    Gain in concentration of B in I hour =0.2
    (i) ∵0.1 mole of A changes to 0.2 mole of B in a given time and thus, n=2
    (ii) Equilibrium constant,
    = 1.2mollitre−1
    (iii) Initial rate of conversion of A = changes in conc. of A during I hour = 
    = 0.1 mol litre−1hour−1
    (iv) ∵ Equilibrium is attained after 5 hr, where [B]=0.6 and [A]=0.3

    For the reaction in equilibrium, A B

    Thus, K is
    • a)
    • b)
    • c)
    • d)
    Correct answer is option 'B'. Can you explain this answer?

    Sushil Kumar answered
    From the  reaction
    -d[A]/dt = d[B] /dt
    ⇒2.3 × 106 [A] = k [B]
     as given in question [B] /[A] = 4 × 108
    so [A] / [B] = 1/ 4 ×108
    ⇒ 2.3 × 106 . [A] /[B] = k
    ⇒  2.3 × 106 / 4 × 108 = k
    Or k = 5.8 × 10-3 /sec¹

    An example of a reversible reaction is:
    • a)
      Pb(NO3)2 (aq) + 2NaI (aq) = PbI2(s) + 2NaNO3(aq)
    • b)
      AgNO3(aq) + HCl(aq) = AgCl(s) + HNO3(aq)
    • c)
      2Na(s) + 2H2O(l) = 2NaOH(aq) + H2(g)
    • d)
      KNO3(aq) + NaCl(aq) = KCl(aq) + NaNO3(aq)
    Correct answer is option 'D'. Can you explain this answer?

    Avinash Mehta answered
    Weak acids and bases may undergo reversible reactions. For example, carbonic acid and water react this way:
    H2CO3 (l) + H2O(l) ⇌ HCO−3 (aq) + H3O+(aq)
    Another example of a reversible reaction is:
    N2O4 ⇆ 2 NO2
    Two chemical reactions occur simultaneously:
    N2O4 → 2 NO2
    2 NO2 → N2O4
    Reversible reactions do not necessarily occur at the same rate in both directions, but they do lead to an equilibrium condition. If dynamic equilibrium occurs, the product of one reaction is forming at the same rate as it is used up for the reverse reaction. Equilibrium constants are calculated or provided to help determine how much reactant and product is formed.
    The equilibrium of a reversible reaction depends on the initial concentrations of the reactants and products and the equilibrium constant, K.

    The units of KP and KC are equal.
    • a)
      true
    • b)
      flase
    Correct answer is option 'B'. Can you explain this answer?

    Vivek Khatri answered
    The units of KP are (atm)Δng and the units of KC are (mol/L)Δng. Where Δng = moles of products – moles of reactants which are in the gaseous state only. As the units of KP and KC are not equal the above statement is considered to be false.

    Consider the following equilibrium in a closed container
    At a fixed temperature, the volume of the reaction container is halved. For this change, which of the following statements hold true regarding the equilibrium constant (Kp) and degree of dissociation (α)?
    • a)
      Neither nor change
    • b)
      Both and change
    • c)
      change but does not change
    • d)
      does not change but change
    Correct answer is option 'D'. Can you explain this answer?

    Basically kp depends on temperature only change in volume doesn't influence it.however degree of dissociation depends upon volume ...so it will change on changing volume.so the answer is ....when the volume of reaction container is halved,equilibrium constant doesn't change but degree of dissociation change.....

    Br2(l) ⇌ Br2(g) is in ________
    • a)
      homogeneous equilibrium
    • b)
      not in both Homogeneous and heterogeneous equilibrium
    • c)
      cannot say
    • d)
      may or may not be in Homogeneous equilibrium
    Correct answer is option 'B'. Can you explain this answer?

    Vandana Gupta answered
    Explanation:

    Homogeneous and Heterogeneous Equilibrium:
    - In a chemical reaction, equilibrium is a state in which the forward and reverse reactions occur at equal rates.
    - A homogeneous equilibrium refers to a reaction in which all the reactants and products are in the same phase (either all gases, all liquids, or all solids).
    - A heterogeneous equilibrium refers to a reaction in which the reactants and products are in different phases (such as a gas and a solid, or a liquid and a solid).

    The given reaction:
    - The given reaction is Br2(l) ⇌ Br2(g).
    - Here, the reactant (Br2) is a liquid and the product (Br2) is a gas.
    - Since the reactant and product are in different phases (liquid and gas), the reaction is in a heterogeneous equilibrium.

    Answer:
    - The correct answer is option 'B' - the reaction is not in both homogeneous and heterogeneous equilibrium.
    - As explained above, the reaction is in a heterogeneous equilibrium due to the different phases of the reactant and product.
    - It is important to note that a reaction can only be in either a homogeneous or a heterogeneous equilibrium, not both at the same time.

    Summary:
    - The given reaction Br2(l) ⇌ Br2(g) is in a heterogeneous equilibrium because the reactant and product are in different phases. Therefore, the correct answer is option 'B'.

    At constant temperature, the pressure is directly proportional to the concentration of the gas.
    • a)
      true
    • b)
      false
    Correct answer is option 'A'. Can you explain this answer?

    Vivek Khatri answered
    We have P = CRT e where p is pressure, R is a universal constant and T is the temperature, we derive the equation from the ideal gas equation PV=nRT. So from P = CRT, we can say that at a constant temperature the pressure is directly proportional to the concentration of the gas.

    WHat is the expression of KC of the chemical equation Ag2O(s) + 2HNO3(aq) ⇌ 2AgNO3(aq) +H2O(l)?
    • a)
      [AgNO3(aq)]2/[HNO3(aq)]2
    • b)
      [AgNO3(aq)]/[HNO3(aq)]2
    • c)
      [AgNO3(aq)]2/[HNO3(aq)]
    • d)
      [AgNO(aq)]2/[HNO3(aq)]2
    Correct answer is option 'A'. Can you explain this answer?

    Anshul Mehra answered
    Explanation:

    The expression for the equilibrium constant (Kc) of a chemical equation is obtained by taking the concentration of the products raised to the power of their stoichiometric coefficients and dividing it by the concentration of the reactants raised to the power of their stoichiometric coefficients.

    In the given chemical equation:

    Ag2O(s) + 2HNO3(aq) → 2AgNO3(aq) + H2O(l)

    The stoichiometric coefficients of the products are 2 for AgNO3(aq) and 1 for H2O(l), while the stoichiometric coefficients of the reactants are 2 for Ag2O(s) and 2 for HNO3(aq).

    Therefore, the expression for Kc is as follows:

    Kc = [AgNO3(aq)]^2 / [HNO3(aq)]^2

    Reasoning:

    To determine the correct expression for Kc, we need to consider the stoichiometry of the reaction. The stoichiometric coefficients in the balanced equation indicate the ratio of reactants and products in the reaction.

    In this case, since 2 moles of AgNO3(aq) are produced for every 2 moles of HNO3(aq) consumed, the concentration of AgNO3(aq) should be squared in the expression for Kc.

    Similarly, since 2 moles of AgNO3(aq) are produced for every 2 moles of HNO3(aq) consumed, the concentration of HNO3(aq) should also be squared in the expression for Kc.

    Conclusion:

    Therefore, the correct expression for Kc is [AgNO3(aq)]^2 / [HNO3(aq)]^2, which is option 'A'. This expression takes into account the stoichiometry of the reaction and correctly represents the equilibrium constant for the given chemical equation.

    One mole of N2O4(g) at 300 K is kept in a closed container under one atmosphere. It is heated to 600 K when 20% by mass of N2O4(g) decomposes to NO2(g). The resultant pressure is:
    • a)
      1.2 atm
    • b)
      2.4 atm
    • c)
      2.0 atm
    • d)
      1.0 atm
    Correct answer is option 'B'. Can you explain this answer?

    Vivek Khatri answered
     
    N2O4 → 2NO2

    moles of unreacted N2O4 = 1 (1 - 0.2) = 0.8

    moles of NO2 = 2 * 0.2 = 0.4
    - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - (+)
    total moles n2 = 0.8 + 0.4 = 1.2

    P1/(T1 n1) = P2/(T2 * n2)

    1/(300 * 1) = P2/(600 * 1.2)

    P2 = 2.4 atm

    If KC of a reaction N2(g) + O2(g) ⇌ 2NO(g) is 2 x 10-3, then what is the KP?
    • a)
      4 x 10-3
    • b)
      1 x 10-3
    • c)
      3 x 10-3
    • d)
      2 x 10-3
    Correct answer is option 'D'. Can you explain this answer?

    Saanvi Roy answered
    To determine the value of KP, the equation relating KP and KC needs to be used. The equation is:

    KP = KC(RT)^(Δn)

    Where:
    KP is the equilibrium constant in terms of partial pressures
    KC is the equilibrium constant in terms of concentrations
    R is the ideal gas constant
    T is the temperature in Kelvin
    Δn is the difference in the number of moles of gas between the products and reactants

    In this reaction, the balanced equation is:

    N2(g) + O2(g) ⇌ 2NO(g)

    The reaction involves 2 moles of gas on the left side (N2 and O2) and 2 moles of gas on the right side (2NO). Therefore, Δn = 2 - 2 = 0.

    Given that KC = 2 x 10^-3, we can use the equation to solve for KP:

    KP = KC(RT)^Δn

    Since Δn = 0, the equation simplifies to:

    KP = KC

    Substituting the given value of KC, we get:

    KP = 2 x 10^-3

    Therefore, the correct answer is option 'D', which is 2 x 10^-3.

    If the equilibrium reaction  is heated, it is observed that the concentration of A increases. Then,
    • a)
      A must be a gas
    • b)
      Either B or C must be solid           
    • c)
      The reaction is exothermic
    • d)
      The reaction is endothermic
    Correct answer is option 'C'. Can you explain this answer?

    Basically when temperature increases,the reactant A utilizes the heat and decomposes into B and C...leading to endothermic reaction( in which heat is utilized)..
    However in above case it is given that when temperature increases,concentration of A increase,it means that A is not utilizing the heat to proceed a forward reaction .....
    so reaction comes to be exothermic....so correct option is C.

    The equilibrium N2(g) + O2(g) ⇌ 2NO(g), is an example of _____________
    • a)
      homogeneous chemical equilibrium
    • b)
      heterogeneous chemical equilibrium
    • c)
      neither homogeneous nor heterogeneous
    • d)
      both homogeneous and heterogeneous
    Correct answer is option 'A'. Can you explain this answer?

    Vivek Khatri answered
    In homogeneous equilibrium, the reactants and products are present in the same phase or physical state. Nitrogen, Oxygen, and nitrogen monoxide are present in a gaseous state, so it is homogeneous chemical equilibrium.

    CO2(g) + C(s) ⇌ 2CO(g) is an example of _____________
    • a)
      homogeneous equilibrium
    • b)
      heterogeneous equilibrium
    • c)
      neither homogeneous nor heterogeneous
    • d)
      both homogeneous and heterogeneous
    Correct answer is option 'B'. Can you explain this answer?

    Ameya Reddy answered
    Heterogeneous equilibrium

    In a chemical reaction, the reactants and products can be either in the same phase (homogeneous) or in different phases (heterogeneous). The given reaction: CO2(g) + C(s) ⇌ 2CO(g) involves reactants and products in different phases, which makes it an example of a heterogeneous equilibrium.

    Explanation:

    Definition:
    A heterogeneous equilibrium is a type of chemical equilibrium in which the reactants and products of a reaction are present in different phases.

    Reactant and Product Phases:
    In the given reaction, CO2(g) is a gas, C(s) is a solid, and 2CO(g) is also a gas. The reactants and products are present in different phases: gas and solid. Therefore, the reaction is an example of a heterogeneous equilibrium.

    Visual Representation:
    CO2(g) + C(s) ⇌ 2CO(g)

    Interpretation:
    The forward reaction involves the reactant CO2(g) and solid C(s) to produce 2CO(g) as products. The reverse reaction involves the reactant 2CO(g) to produce CO2(g) and C(s) as products.

    Phase Change:
    In the forward reaction, the reactant CO2(g) is a gas and the reactant C(s) is a solid. During the reaction, the solid carbon (C) combines with the gaseous carbon dioxide (CO2) to form gaseous carbon monoxide (CO). This phase change from solid to gas and gas to solid indicates a heterogeneous equilibrium.

    Presence of Different Phases:
    The presence of different phases (gas and solid) in the reactants and products of the reaction indicates a heterogeneous equilibrium. This means that the reaction does not occur entirely in one phase, but involves a mixture of phases.

    Therefore, the given reaction CO2(g) + C(s) ⇌ 2CO(g) is an example of a heterogeneous equilibrium.

    For the following equation, 2HBr(g) ⇌ H2(g) + Br2(g); are both KP and KC are equal?
    • a)
      yes
    • b)
      cannot say
    • c)
      no
    • d)
      depends on the temperature
    Correct answer is option 'A'. Can you explain this answer?

    Vivek Khatri answered
    We have here KC = [H2][Br2]/[HBr]2; KP = [pH2][pBr2]/[pHBr]2, where pH2 = [H2]RT, pBr2 = [Br2]RT and [pHBr] = [HBr]RT. So in this case as Δng = 0, where Δng = moles of products – moles of reactants which are in gaseous state only, both KP and KC are equal.

    When two reactants, A and B are mixed to give products, C and D, the reaction quotient, (Q) at the initial stages of the reaction:
    • a)
      Is zero
    • b)
      Decreases with time
    • c)
      Is independent of time
    • d)
      Increases with time
    Correct answer is option 'D'. Can you explain this answer?

    Juhi Sen answered
    The reaction quotient (Q) and its relation to reactants and products

    The reaction quotient (Q) is a measure of the relative concentrations of reactants and products in a chemical reaction at any given point in time. It is calculated in the same way as the equilibrium constant (K), but it is determined using the concentrations of reactants and products at any moment during the reaction, rather than at equilibrium.

    Initial stages of the reaction

    In the initial stages of a reaction, before equilibrium is reached, the concentrations of reactants are typically higher compared to the concentrations of products. This is because the reaction has just started, and the products have not had enough time to form in significant amounts. As a result, the value of Q in the initial stages of the reaction is generally smaller than the equilibrium constant, K.

    Understanding the options

    a) Is zero: This option is incorrect because it implies that no products are formed at the initial stages of the reaction, which is not true. Some products will be present, although in smaller amounts compared to the reactants.

    b) Decreases with time: This option is also incorrect because the value of Q does not necessarily decrease with time. It depends on the specific reaction and the rate at which reactants are converted to products.

    c) Is independent of time: This option is incorrect because Q changes with time as the reaction progresses. Initially, Q will be smaller than K, but as the reaction proceeds, Q will approach the value of K.

    d) Increases with time: This option is the correct answer. As the reaction progresses, reactants are consumed, and products are formed. This leads to an increase in the concentrations of products and a decrease in the concentrations of reactants. Consequently, the value of Q increases with time and approaches the value of K as equilibrium is approached.

    Conclusion

    In summary, the reaction quotient (Q) at the initial stages of a reaction is smaller than the equilibrium constant (K). As the reaction progresses, Q increases with time and approaches the value of K. The correct answer to the given question is option 'D'.

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