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Chemistry
Chemical Equilibrium
Previous Years Questions

Numerical

4.5 moles each of hydrogen and iodine is heated in a sealed ten litre vessel. At equilibrium, 3 moles of $$\mathrm{HI}$$ were found. The equilibrium c...
A mixture of 1 mole of $$\mathrm{H}_{2} \mathrm{O}$$ and 1 mole of $$\mathrm{CO}$$ is taken in a 10 litre container and heated to $$725 \mathrm{~K}$$....
$$\mathrm{A}(g) \rightleftharpoons 2 \mathrm{~B}(g)+\mathrm{C}(g)$$ For the given reaction, if the initial pressure is $$450 \mathrm{~mm} ~\mathrm{Hg}...
The number of correct statement/s involving equilibria in physical processes from the following is ________ (A) Equilibrium is possible only in a clos...
The equilibrium composition for the reaction $$\mathrm{PCl}_{3}+\mathrm{Cl}_{2} \rightleftharpoons \mathrm{PCl}_{5}$$ at $$298 \mathrm{~K}$$ is given ...
(i) $$\mathrm{X}(\mathrm{g}) \rightleftharpoons \mathrm{Y}(\mathrm{g})+\mathrm{Z}(\mathrm{g}) \quad \mathrm{K}_{\mathrm{p} 1}=3$$ (ii) $$\mathrm{A}(\m...
For reaction : $$\mathrm{SO}_{2}(\mathrm{~g})+\frac{1}{2} \mathrm{O}_{2}(\mathrm{~g}) \rightleftharpoons \mathrm{SO}_{3}(\mathrm{~g})$$ $$\mathrm{K}_{...
Consider the following equation: $2 \mathrm{SO}_{2}(g)+\mathrm{O}_{2}(g) \rightleftharpoons 2 \mathrm{SO}_{3}(g), \Delta H=-190 \mathrm{~kJ}$ The n...
At 298 K $$\mathrm{N_2~(g)+3H_2~(g)\rightleftharpoons~2NH_3~(g),~K_1=4\times10^5}$$ $$\mathrm{N_2~(g)+O_2~(g)\rightleftharpoons~2NO~(g),~K_2=1.6\times...
Water decomposes at 2300 K $$\mathrm{H_2O(g)\to H_2(g)+\frac{1}{2}O_2(g)}$$ The percent of water decomposing at 2300 K and 1 bar is ___________ (Neare...
Consider the following reaction approaching equilibrium at 27$$^\circ$$C and 1 atm pressure $$\mathrm{A+B}$$ $$\mathrel{\mathop{\kern0pt\rightleftharp...
At $$600 \mathrm{~K}, 2 \mathrm{~mol}$$ of $$\mathrm{NO}$$ are mixed with $$1 \mathrm{~mol}$$ of $$\mathrm{O}_{2}$$. $$2 \mathrm{NO}_{(\mathrm{g})}+\m...
At $$298 \mathrm{~K}$$, the equilibrium constant is $$2 \times 10^{15}$$ for the reaction : $$\mathrm{Cu}(\mathrm{s})+2 \mathrm{Ag}^{+}(\mathrm{aq}) \...
A box contains 0.90 g of liquid water in equilibrium with water vapour at 27$$^\circ$$C. The equilibrium vapour pressure of water at 27$$^\circ$$C is ...
2NOCl(g) $$\rightleftharpoons$$ 2NO(g) + Cl2(g) In an experiment, 2.0 moles of NOCl was placed in a one-litre flask and the concentration of NO after ...
40% of HI undergoes decomposition to H2 and I2 at 300 K. $$\Delta$$G$$^\Theta $$ for this decomposition reaction at one atmosphere pressure is _______...
The standard free energy change ($$\Delta$$G$$^\circ$$) for 50% dissociation of N2O4 into NO2 at 27$$^\circ$$C and 1 atm pressure is $$-$$ x J mol$$-$...
PCl5 dissociates as PCl5(g) $$\rightleftharpoons$$ PCl3(g) + Cl2(g) 5 moles of PCl5 are placed in a 200 litre vessel which contains 2 moles of N2 and ...
2O3(g) $$\rightleftharpoons$$ 3O2(g) At 300 K, ozone is fifty percent dissociated. The standard free energy change at this temperature and 1 atm press...
When 5.1 g of solid NH4HS is introduced into a two litre evacuated flask at 27$$^\circ$$C, 20% of the solid decomposes into gaseous ammonia and hydrog...
The number of moles of NH3, that must be added to 2L of 0.80 M AgNO3 in order to reduce the concentration of Ag+ ions to 5.0 $$\times$$ 10$$-$$8 M (Kf...
The equilibrium constant Kc at 298 K for the reaction A + B $$\rightleftharpoons$$ C + D is 100. Starting with an equimolar solution with concentratio...
The reaction rate for the reaction[PtCl4]2$$-$$ + H2O $$\rightleftharpoons$$ [Pt(H2O)Cl3]$$-$$ + Cl$$-$$was measured as a function of concentrations o...
The OH$$-$$ concentration in a mixture of 5.0 mL of 0.0504 M NH4Cl and 2 mL of 0.0210 M NH3 solution is x $$\times$$ 10$$-$$6 M. The value of x is ___...
The equilibrium constant for the reactionA(s) $$\rightleftharpoons$$ M(s) + $${1 \over 2}$$O2(g)is Kp = 4. At equilibrium, the partial pressure of O2 ...
PCl5 $$\rightleftharpoons$$ PCl3 + Cl2Kc = 1.8443.0 moles of PCl5 is introduced in a 1 L closed reaction vessel at 380 K. The number of moles of PCl5 ...
Assuming that Ba(OH)2 is completely ionised in aqueous solution under the given conditions the concentration of H3O+ ions in 0.005 M aqueous solution ...
For the reactionA + B $$\rightleftharpoons$$ 2Cthe value of equilibrium constant is 100 at 298 K. If the initial concentration of all the three specie...
Value of KP for the equilibrium reactionN2O4(g) $$\rightleftharpoons$$ 2NO2(g) at 288 K is 47.9. The KC for this reaction at same temperature is _____...
2SO2(g) + O2(g) $$\rightleftharpoons$$ 2SO3(g)In an equilibrium mixture, the partial pressures are PSO3 = 43 kPa; PO2 = 530 Pa and PSO2 = 45 kPa. The ...
The gas phase reaction $$2A(g) \rightleftharpoons {A_2}(g)$$ at 400 K has $$\Delta$$Go = + 25.2 kJ mol-1.The equilibrium constant KC for this reaction...
Consider the reaction $$N_{2}O_{4}\left( g\right) \rightleftharpoons 2NO_{2}\left( g\right) $$The temperature at which KC = 20.4 and KP = 600.1, is...
0.01 moles of a weak acid HA (Ka = 2.0 $$\times$$ 10$$-$$6) is dissolved in 1.0 L of 0.1 M HCl solution. The degree of dissociation of HA is _________...
For the reaction $$A(g) \rightleftharpoons B(g)$$ at 495 K, $$\Delta$$rG$$^\circ$$ = $$-$$9.478 kJ mol$$-$$1.If we start the reaction in a closed cont...
A homogeneous ideal gaseous reaction $$A{B_{2(g)}} \rightleftharpoons {A_{(g)}} + 2{B_{(g)}}$$ is carried out in a 25 litre flask at 27$$^\circ$$C. Th...
The stepwise formation of $${\left[ {Cu{{\left( {N{H_3}} \right)}_4}} \right]^{2 + }}$$ is given below: The value of stability constants K1, K2, K3 a...
At 1990 K and 1 atm pressure, there are equal number of Cl2, molecules and Cl atoms in the reaction mixture. The value of Kp for the reaction Cl2 (g) ...
For the reaction A(g) $$ \to $$ B(g) the value of the equilibrium constant at 300 K and 1 atm is equal to 100.0. The value of $$\Delta $$rG for the re...
For a reaction X + Y ⇌ 2Z , 1.0 mol of X, 1.5 mol of Y and 0.5 mol of Z were taken in a 1 L vessel and allowed to react. At equilibrium, the concentra...

MCQ (Single Correct Answer)

For a concentrated solution of a weak electrolyte ($$\mathrm{K}_{\text {eq }}=$$ equilibrium constant) $$\mathrm{A}_{2} \mathrm{B}_{3}$$ of concentra...
The equilibrium constant for the reversible reaction 2A(g) $$\rightleftharpoons$$ 2B(g) + C(g) is K1 $${3 \over 2}$$A(g) $$\rightleftharpoons$$ $${3 \...
4.0 moles of argon and 5.0 moles of PCl5 are introduced into an evacuated flask of 100 litre capacity at 610 K. The system is allowed to equilibrate. ...
For a reaction at equilibrium A(g) $$\rightleftharpoons$$ B(g) + $${1 \over 2}$$ C(g) the relation between dissociation constant (K), degree of dissoc...
The value of KC is 64 at 800 K for the reaction N2(g) + 3H2(g) ⇌ 2NH3(g) The value of KC for the following reaction is : NH3(g) ⇌ $${1 \over 2}$$N2(g)...
For the reaction Fe2N(s) + $${3 \over 2}$$H2(g) ⇌ 2Fe(s) + NH3(g)
The variation of equilibrium constant with temperature is given below : .tg {border-collapse:collapse;border-spacing:0;} .tg td{border-color:black;b...
Consider the following reaction: N2O4(g) ⇌ 2NO2(g); $$\Delta $$Ho = +58 kJ For each of the following cases (a, b), the direction in which the equilibr...
If the equilibrium constant for A ⇌ B + C is $$K_{eq}^{(1)}$$ and that of B + C ⇌ P is $$K_{eq}^{(2)}$$, the equilibrium constant for A ⇌ P is :...
For the equilibrium A ⇌ B , the variation of the rate of the forward (a) and reverse (b) reaction with time is given by :
An open beaker of water in equilibrium with water vapour is in a sealed container. When a few grams of glucose are added to the beaker of water, the r...
In the figure shown below reactant A (represented by square) is in equilibrium with product B (represented by circle). The equilibrium constant is : ...
The INCORRECT match in the following is :
In which one of the following equilibria, Kp $$ \ne $$ KC ?
For the reaction, 2SO2(g) + O2(g) = 2SO3(g), $$\Delta $$H = –57.2 kJ mol–1 and KC = 1.7 × 1016 Which of the following statement is incorrect ? ...
For the following reactions, equilibrium constants are given : S(s) + O2(g) ⇋ SO2(g); K1 = 1052 2S(s) + 3O2(g) ⇋ 2SO3(g); K2 = 10129 The equilibriu...
In a chemical reaction, the initial concentration of B was 1.5 times of the concentration of A, but the equilibrium concentrations of A and B were f...
Two solids dissociate as follows – The total pressure when both the solids dissociated simultaneously is - ...
Consider the reaction N2(g) + 3H2(g) $$\rightleftharpoons$$ 2NH3(g) The equilibrium constant of the above reaction is Kp. If pure ammonia is lef...
5.1 g NH4SH is introduced in 3.0 L evacuated flask at 327ºC. 30% of the solid NH4SH decomposed to NH3 and H2S as gases . The Kp of the reaction at 327...
The values of Kp/Kc for the following reactions at 300 K are, respectively : (At 300 K, RT = 24.62 dm3 atm mol–1) N2(g) + O2(g)  $$\rightle...
Consider the following reversible chemical reactions : The relation between K1 and K2 is : ...
The gas phase reaction 2NO2(g) $$ \to $$ N2O4(g) is an exothermic reaction. The decomposition of N2O4, in equilibrium mixture of NO2(g) and N2O4(g),...
At a certain temperature in a $$5$$ $$L$$ vessel, 2 moles of carbon monoxide and 3 moles of chlorine were allowed to reach equilibrium according to th...
In which of the following reactions, an increase in the volume of the container will favour the formation of products?
The following reaction occurs in the Blast Furnace where iron ore is reduced to iron metal : Fe2O3(s) + 3 CO(g) $$\rightleftharpoons$$ 2 Fe(1) + 3 CO2...
A solid XY kept in an evacuated sealed container undergoes decomposition to form a mixture of gases X and Y at temperature T. The equilibrium pressure...
The equilibrium constant at 298 K for a reaction A + B $$\leftrightharpoons$$ C + D is 100. If the initial concentration of all the four species were ...
The standard Gibbs energy change at 300 K for the reaction 2A $$\leftrightharpoons$$ B + C is 2494.2 J. At a given time, the composition of the reacti...
For the reaction SO2 (g) + $${1 \over 2} O_2(g) \leftrightharpoons$$ SO3(g). if KP = KC(RT)x where the symbols have usual meaning then the value of ...
The equilibrium constant (KC) for the reaction N2(g) + O2(g) $$\to$$ 2NO(g) at temperature T is 4 $$\times$$ 10–4. The value of KC for the reaction, N...
A vessel at 1000 K contains CO2 with a pressure of 0.5 atm. Some of the CO2 is converted into CO on the addition of graphite. If the total pressure at...
In aqueous solution the ionization constants for carbonic acid are K1 = 4.2 x 10–7 and K2 = 4.8 x 10–11 Select the correct statement for a saturated 0...
The equilibrium constants KP1 and KP2 for the reactions X $$\leftrightharpoons$$ 2Y and Z $$\leftrightharpoons$$ P + Q, respectively are in the ratio...
For the following three reactions a, b and c, equilibrium constants are given: a. CO (g) + H2O (g) $$\leftrightharpoons$$ CO2(g) + H2 (g) ; K1 b. CH4...
Phosphorus pentachloride dissociates as follows, in a closed reaction vessel PCl5 (g) $$\leftrightharpoons$$ PCl3 (g) + Cl2 (g) If total pressure at ...
The equilibrium constant for the reaction SO3 (g) $$\leftrightharpoons$$ SO2 (g) + $$1 \over 2$$ O2 (g) is Kc = 4.9 $$\times$$ 10–2. The value of Kc...
The exothermic formation of ClF3 is represented by the equation: Cl2 (g) + 3F2 (g) $$\leftrightharpoons$$ 2ClF3 (g); $$\Delta H$$ = -329 kJ Which of ...
For the reaction 2NO2 (g) $$\leftrightharpoons$$ 2NO (g) + O2 (g), (Kc = 1.8 $$\times$$ 10-6 at 184oC) (R = 0.0831 kJ/(mol. K)) When Kp and Kc are com...
An amount of solid NH4HS is placed in a flask already containing ammonia gas at a certain temperature and 0.50 atm. Pressure. Ammonium hydrogen sulphi...
What is the equilibrium expression for the reaction P4 (s) + 5O2 $$\leftrightharpoons$$ P4O10 (s)?
For the reaction, CO(g) + Cl2(g) $$\leftrightharpoons$$ COCl2(g) the $${{{K_p}} \over {{K_c}}}$$ is equal to :
The equilibrium constant for the reaction N2(g) + O2(g) $$\leftrightharpoons$$ 2NO(g) at temperature T is 4 $$\times$$ 10-4. The value of Kc for the r...
Consider the reaction equilibrium 2 SO2 (g) + O2 (g) $$\leftrightharpoons$$ 2 SO3 (g); $$\Delta H^o$$ = -198 kJ One the basis of Le Chatelier's princi...
For the reaction equilibrium N2O4 (g) $$\leftrightharpoons$$ 2NO2 (g) the concentrations of N2O4 and NO2 at equilibrium are 4.8 $$\times$$ 10-2 and 1...
Change in volume of the system does not alter which of the following equilibria?
For the reaction CO (g) + (1/2) O2 (g) $$\leftrightharpoons$$ CO2 (g), Kp/Kc is :

MCQ (More than One Correct Answer)

The effect of addition of helium gas to the following reaction in equilibrium state, is : $$\mathrm{PCl}_{5}(\mathrm{g}) \rightleftharpoons \mathrm{PC...
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