All questions of Equilibrium for ACT Exam

Ca(HCO₃)₂ is strongly heated and after equilibrium is attained, temperature changed to 25° C.

K_p = 36 (pressure taken in atm)
Thus, pressure set up due to CO₂ is

• a)
  36 atm
• b)
  18 atm
• c)
  12 atm
• d)
  6 atm

• a)
  Equilibrium
• b)
  Mass action
• c)
  Constant proportion
• d)
  Reciprocal proportions

Graphite is added to a vessel that contains CO₂(g) at a pressure of 0.830 atm at a certain high temperature. The pressure rises due to a reaction that produces CO (g). The total pressure reaches an equilibrium value of 1.366 atm. Calculate the equilibrium constant of the following reaction.

• a)
  2.909 atm
• b)
  6.909 atm
• c)
  4.909 atm
• d)
  3.909 atm

• a)
  Equilibrium is possible only in a closed system at a given temperature.
• b)
  All measurable properties of the system remain constant.
• c)
  All the physical processes stop at equilibrium.
• d)
  The opposing processes occur at the same rate and there is dynamic but stable condition.

Assume following equilibria when total pressure set up in each are equal to 1 atm, and equilibrium constant (K_p) as K₁; K₂ and K₃


Thus,

• a)
   K₁ = K₂ = K₃
• b)
  K₁ < K₂ < K₃
• c)
  K₃ < K₂ < K₁
• d)
  None of these

Following equilibrium is set up at 1000 K and 1 bar in a 5 L flask,

At equilibrium, NO₂ is 50% o f the total volume. Thus, equilibrium constant K_c is 

• a)
  0.133
• b)
  0.266
• c)
  0.200
• d)
  0.400

Direction (Q. Nos. 1-10) This section contains 10 multiple choice questions. Each question has four
choices (a), (b), (c) and (d), out of which ONLY ONE option is correct.

Q. Vapour pressure of NH₄HS (s)is 20 mm at 25°C, for

Total pressure when NH₄HS (s) dissociates at 25°Cin a vessel which already contains H₂S (g)at a pressure of 15 mm, is

• a)
  25 mm
• b)
  50 mm
• c)
  5 mm
• d)
  10 mm

Passage II

The complex ion of Fe²⁺ with the chelating agent dipyridyl (abbreviated dipy) has been studied kinetically in both the forward and backward directions. For the complexion reaction,

the rate of the formation of the complex at 298 K is given by rate = (1. 45 x 10¹³ L³mol ^-3s^-1) [Fe ²⁺] [dipy]³ and for the reverse reaction , the rate of disapperance of the complex is

Q. What is equilibrium constant for the equilibrium ? 

• a)
  8.4138x 10^-18
• b)
  2.3770x 10¹⁷
• c)
  1.1885x 10¹⁷
• d)
  5.9426x 10⁶

Following equilibrium is set up at 298 K in a 1 L flask.

If one starts with 2 moles of A and 1 mole of B, it is found that moles of B and D are equal.Thus K_c is 

• a)
  9.0
• b)
  15.0
• c)
  3.0
• d)
  0.0667

• a)
  Reversible reaction
• b)
  Cyclic reaction
• c)
  Decomposition reaction
• d)
  Irreversible reaction

• a)
   0.20 bar
• b)
   0.017 ba
• c)
  0.040 bar
• d)
  0.10 bar

For the following gaseous phase equilibrium,

K_p is found to be equal to K_x (K_x 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

Variation of log K_p with temperature. 1/T is given by for the equilibrium.
NH₄HS (s)   NH₃(g) + H₂S

Q. The equilibrium is displaced in forward side on

• a)
  increasing temperature and decreasing pressure
• b)
  increasing temperature and pressure both
• c)
  decreasing temperature and pressure both
• d)
  decreasing temperature and increasing pressure

Q. What is [PCI₅] eq?

• a)
  4.09 x 10^-4 mol L^-1
• b)
  2.444 x 10³ mol L^-1 
• c)
  4.09 x 10^-6 mol L^-1
• d)
  2.444 x 10⁵ mol L^-1

H₂O (l) H₂O(s) ; ΔH = -q

Application of pressure on this equilibrium

• a)
  cause formation of more ice
• b)
  cause fusion of ice
• c)
  has no effect
• d)
  lower the melting point

For the reversible reaction, 

In a reaction vessel, [NO]= [O₂]= 0.01 mol L^-1 and [NO₂]= 0.1 mol L^-1 then above reaction is 

• a)
  shifted in forward direction
• b)
  shifted in backward direction
• c)
  in equilibrium
• d)
  not predictable in the absence of required data

Passage I

Solid ammonium chloride is in equilibrium with ammonia and hydrogen chloride gases

0.980 g of solid NH₄CI is taken in a closed vessel of 1 L capacity and heated to 275° C.

Q. Percentage decomposition of the original sample is

• a)
  24.81%
• b)
  6.24%
• c)
  3.12%
• d)
  12.13%

• a)
  20 percent
• b)
  33 percent
• c)
  100 percent
• d)
  98 percent

For the following electrochemical cell reaction at 298 K,
 
E^°cell = 1.10 V

• a)
  0.027
• b)
  37.22
• c)
  0.012
• d)
  85.73

Kc forthe decomposition of NH₄HS(s) is 1.8x 10^-4 at 25°C.

If the system already contains [NH₃] = 0.020 M, then when equilibrium is reached, molar concentration are

• a)
  a
• b)
  b
• c)
  c
• d)
  d

Ag⁺(aq)+NH₃(aq) [Ag(NH₃)(aq)]⁺ ; K, = 3.5x 10^-3
[Ag(NH₃)]⁺ (aq)+NH₃(aq) [Ag(NH₃)₂]²⁺(aq); K₂ = 1.7x 10^-3
Formation constant of [Ag(NH₃)₂]⁺(aq) is

• a)
  2.06
• b)
  5.2 x 10^-3
• c)
  5.95 x 10^-6
• d)
  None of these

Consider the following equilibrium in a closed container

At a fixed temperature, the volume of a reaction container is halved. For this change, which of the following statements holds true regarding the equilibrium constant (K_p) and degree of dissociation (α) ?

• a)
  Neither K_p nor α change
• b)
  Both K_p and α change
• c)
  K_p changes but α does not change
• d)
  K_p does not change but α changes

 is a gaseous phase equilibrium reaction taking place at 400 K in a 5 L flask. For this 

• a)
  K_c = K_p
• b)
  K_c = 25Kp
• c)
  K_p = 25K_c
• d)
  K_c = 5K_p 

The equilibrium constant for the following reaction, is 1.6 x 10⁵ at 1024 K.

HBr (g)at 10.0 bar is introduced into a sealed container at 1024 K. Thus, partial pressure of H₂(g)and Br₂(g), together is

• a)
  10 bar
• b)
  0.05 bar
• c)
  0.025 bar
• d)
  0.10 bar

• a)
  
• b)
  
• c)
  N₂O₄(g)  2NO₂(g)
• d)
  

A sample of N₂O₄(g)with a pressure of 1.00 atm is placed in a flask. When equilibrium is reached, 20% of N₂O₄(g)has been converted to NO₂(g)

If the original pressure is made 10% of the earlier pressure, then per cent dissociation will be

• a)
  20%
• b)
  42%
• c)
  54%
• d)
  62%

• a)
  0.0174
• b)
  0.174
• c)
  0.0348
• d)
  1.74

• a)
  0.1 mol dm^–3 AgNO₃ solution
• b)
  0.1 mol dm^–3 HCl solution
• c)
  H₂O
• d)
  Aqueous ammonia​

For the reaction, 
if K_p = K_c (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

At 273 K and 1 atm, 1 L of N₂O₄ (g) decomposes to NO₂(g)a s given,

At equilibrium, original volume is 25% less than the existing volume. Percentage decomposition of N₂O₄ (g) is thus, 

• a)
  25%
• b)
  50%
• c)
  66.66%
• d)
  33.33%

Direction (Q. Nos. 1-8) This section contains 8 multiple choice questions. Each question has four
choices (a), (b), (c) and (d), out of which ONLY ONE option is correct.

Q. For the following equilibrium,

Vapour density is found to be 100 when 1 mole of PCI₅ is taken in 10 dm³ flask at 300 K. Thus, equilibrium pressure is

• a)
  1.00 atm
• b)
  4.92 atm
• c)
  2.46 atm
• d)
  2.57 atm

For the following equilibrium, N₂O₄ (g) 2NO₂(g)

K_p = K_C. This is attained when

• a)
  T = 1.0K
• b)
  T = 12.18 K
• c)
  T = 27.3 K
• d)
  T = 273 K

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)
  

When hydrochloric acid is added to cobalt (II) nitrate solution at room temperature, the following reaction takes place

Q. The solution is blue at room temperature. However, it turns pink when cooled in a freezing mixture. Based upon this information, which of the following expression is correct for the forward reaction?

• a)
  ΔH > 0
• b)
  ΔH < 0
• c)
  ΔH = 0
• d)
  The sign of ΔH can’t be predicted based on the given information

• a)
  all types of system
• b)
  closed system
• c)
  open system
• d)
  isolated system

A gaseous phase reaction taking place in 1L flask at 400 K is given, 

Starting with 1 mole N₂ and 3 moles H₂, equilibrium mixture required 250 mL of 1M H₂SO₄ . Thus, K_c is 

• a)
  0.006
• b)
  0.08
• c)
  0.029
• d)
  2.05

Combustion of CO(g)can be increased in the following reaction by

• a)
  decreasing volume at constant temperature
• b)
  adding argon gas
• c)
  adding O₂ gas
• d)
  decreasing pressure at constant temperature

• A:

  ammonia

• B:

  sulfuric acid

• C:

  lactic acid

• D:

  both A and B

The answer is d.

Direction (Q. Nos. 16-19) This section contains  a paragraph, each describing theory, experiments, data etc. three Questions related to paragraph have been given.Each question have only one correct answer among the four given options (a),(b),(c),(d)

Passage I
The equilibrium reaction  has been thoroughly studied K_p = 0.148 at 298 K

If the total pressure in a flask containing NO₂ and N₂O₄ gas at 25°C is 1.50 atm, what fraction of the N₂O₄ has dissociated to NO₂ ? 

• a)
  0.156
• b)
  0.844
• c)
  0.024
• d)
  0.076

H₂S (g) initially at a pressure of 10.0 atm and a temperature of 800 K, dissociates as

At equilibrium, the partial pressure of S₂ vapour is 0.020 atm . Thus, K_p is 

• a)
  3.23x 10^-7
• b)
  6.45x 10^-7
• c)
  1.55x 10⁶
• d)
  6.20x 10⁷

Passage lI

One of the reactions that takes place in producing steel from iron ore is the reduction of iron (II) oxide by carbon monoxide to give iron metal and carbon dioxide.

Initial partial pressure
CO(g) = 1.40 atm
CO₂(g) = 0.80 atm

Q. Under the given partial pressure, reaction is

• a)
  displaced in forward side
• b)
  displaced in backward side
• c)
  in equilibrium
• d)
  incomplete in the absence of total pressure

Select the correct statement (s) about the following equilibrium.

• a)
  At constant vapour pressure, number of molecules leaving the liquid equals the number returning to liquid from vapour
• b)
  This does not represent the static equilibrium
• c)
  This represents dynamic equilibrium and the rate of the forward and backward reactions become equal
• d)
  This represents dynamic as well as static equilibrium

For the reaction,

2SO₂ (g) + O₂ (g)2SO₃ (g) + 188.3 KJ

the number of moles of SO₃ formed is increased if

• a)
  temperature is increased at constant V
• b)
  inert gas is added to the mixture
• c)
  O₂ is removed from the mixture
• d)
  volume of the reaction flask is decreased

• a)
  nRT
• b)
  1/RT
• c)
  (RT)²
• d)
  1/RT²

For the equilibrium,

at 1000 K. If at equilibrium p_CO = 10 then total pressure at equilibrium is 

• a)
  6.30 atm
• b)
  0.63 atm
• c)
  6.93 atm
• d)
  69.3 atm

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

In the following equilibrium  AB  A⁺ + B^-
AB is 10% dissociated, when [AB] = 1M

Q. What is per cent dissociation if 1 M AB is dissociated in the presence of 1 M A⁺? 

• a)
  5.2%
• b)
  6.0%
• c)
  1.1%
• d)
  10.0%