CHEMICAL - EQUILIBRIA

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1 . Favourable conditions for manufacture of ammonia by the reaction, N + H NH ; H =.9 kcal are: (a) Low temperature, low pressure and catalyst (b) Low temperature, high pressure and catalyst (c) High temperature, low pressure and catalyst (d) High temperature, high pressure and catalyst. For an equilibrium reaction involving gases, the forward reaction is Ist order while the reverse reaction is IInd order. The units of K p for the forward equilibrium is : (a) atm (b) atm (c) atm (d) atm. At equilibrium, if Kp =, then: (a) G = 0 (b) G > (c) G < (d) None 4. On applying pressure to the equilibrium, ice water Which phenomenon will happen: (a) More ice will be formed (b) More water will be formed (c) Equilibrium will not be disturbed (d) Water will evaporate 5. If K and K are equilibrium constants for reactions (I) and (II) respectively for, N + O NO... (i) Then: N + O NO... (ii) (a) K = K (b) K = K (c) K = K (d) K = (/)K 6. If pressure is applied to the equilibrium of solid liquid. The melting point of the solid: (a) Will not change CHEMICAL - EQUILIBRIA (b) May increase or decrease depending upon its nature (c) Will always increase (d) Will always decrease 7. The equilibrium constants for the reactions are: K H H + + H ; K H K K H + + H ; K H H + + ; K The equilibrium constant for H H + + will be : (a) K /K K (b) K K K (c) K /K K (d) K + K + K 8. For a hypothetical equilibrium : 4A + 5B 4x + 6y ; The equilibrium constant K c has the unit: (a) mol litre (b) litre mol (c) litre mol (d) mol litre 9. In which of the following cases, does the reaction go farthest to completion: (a) K = 0 (b) K = 0 (c) K = 0 (d) K = 0. In the dissociation of, HI H + I, the degree of dissociation will be influenced by the: (a) Addition of inert gas at constant volume (b) Addition of inert gas at constant pressure (c) Increase of temperature (d) Increase of pressure. If K and K are the respective equilibrium constants for the two reactions, XeF 6 (g) + H O(g) XeOF 4 (g) + HF(g) XeO 4 (g) + XeF 6 (g) XeOF 4 (g) +XeO F (g) The equilibrium constant for the reaction, XeO 4 (g) + HF(g) XeO F (g) + H O(g) is: (a) K K (b) K /K (c) K /K (d) K /K Page No.:

2 . For the reaction, N + H NH in a vessel, after the addition of equal number of mole of N and H, equilibrium state is formed. Which of the following is correct : (a) [H ] = [N ] (b) [H ] < [N ] (c) [H ] > [N ] (d) [H ] > [NH ]. Consider the reaction, CH COOH + C OH CH COOC + H O One mole each of CH COOH and C OH are heated in the presence of little concentrated H SO 4. On equilibrium: (a) mole of ethyl acetate is formed (b) mole of ethyl acetate are formed (c) / mole of ethyl acetate are formed (d) / mole of ethyl acetate are formed 4. For the reactions, A B ; K c = B C ; K c = 4 C D ; K c = 6 K c for the reaction, A D is: (a) ( ) (b) ( 4)/6 (c) (4 6)/ (d) 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 6. 4 mole of A are mixed with 4 mole of B, when mole of C are formed at equilibrium, according to the reaction, A + B C + D. The equilibrium constant is: (a) 4 (b) (c) (d) 4 7. The equilibrium constant for a reaction is 0 0 at 00 K. The standard free energy change for this reaction is: Page No.: (a) 5 kj (b) +5 kj (c) +66 kj (d) 66 kj 8. At a certain temperature, HI H + I only 50% HI is dissociated at equilibrium. The equilibrium constant is: (a).0 (b).0 (c) 0.5 (d) The vapour density of undecomposed N O 4 is 46. When heated, vapour density decreases to 4.5 due to its dissociation to NO. The per cent dissociation of N O 4 at the final temperature is: (a) 87 (b) 60 (c) 40 (d) The equilibrium constant for the reaction, Br Br at 500 K and 700 K are 0 0 and 0 5 respectively. The reaction is: (a) Endothermic (b) Exothermic (c) Fast (d) Slow. G for the reaction X + Y Z is ve 606 kcal. The equilibrium constant for the reaction at 7 C is: (a) 00 (b) 0 (c) (d) 0.0. The equilibrium constant of a reaction is 0.0. At equilibrium, the rate constant of forward reaction is 0.0. The rate constant for backward reaction is: (a) 0.5 (b).0 (c) 0.0 (d) In the reaction, PCl 5 PCl + Cl, the amounts of PCl 5, PCl and Cl at equilibrium are mole each and the total pressure is atm. The equilibrium constant K p is: (a).0 atm (b).0 atm (c).0 atm (d) 6.0 atm 4. At temperature, T, a compound AB (g) dissociates according to the reaction AB (g) AB(g) + B (g) with a degree of dissociation x, which is small compared with unity. The expression for K p, in terms of x and

3 the total pressure, P is: (a) Px (c) Px 5. K c for the reaction : (b) Px (d) [Ag(CN) ] Ag + + CN, the equilibrium constant at 5 C is , then the silver ion concentration in a solution which was originally 0. molar in KCN and 0.0 molar in AgNO is. (a) (b) (c) (d) In a system: A(s) B(g) + C(g). If the concentration of C at equilibrium is increased by a factor, it will cause the equilibrium concentration of B to change to: (a) Two times of its original value (b) One half of its original value (c) times of its original value (d) / times of its original value 7. In the reaction, C(s) + CO (g) CO(g), the equilibrium pressure is atm. If 50% of CO reacts, K p for the change is: (a) atm (c) 0 atm (b) 6 atm (d) 6 atm 8. If CuSO 4.5H O(s) CuSO 4.H O(s) + H O(v) K p = atm at 5 C. The efflorescent nature of CuSO 4.5H O can be noticed when vapour pressure of H O in atmosphere is: (a) > 7.9 mm (b) < 7.9 mm (c) < > 7.9 mm (d) None 9. Two moles of NH gas are introduced into a previously evacuated.0 litre container, in which it undergoes dissociation at high temperature NH (g) N (g) + H (g). At equilibrium.0 mole of NH (g) is left. The value of the equilibrium constant K c (in units of mol litre ) will be (a) 0.75 (b) 0.70 (c).75 (d) In the qualitative analysis of ferric ions, ammonium thiocyanate is added to the solution, which provides red colour with Fe + ions due to formation of complex according to the reaction Fe + + 6NH 4 CNS [Fe(CNS) 6 ]+ 6NH + 4 If some quantity of NH + is eliminated at 4 equilibrium, then (a) red colour is disappeared (b) the colour will be darken (c) no change in colour (d) red colour turns to blue. The following equilibria are given Px I: N + H NH ; K II: N +O NO ; K III: H + 5 O H O ; K, the equilibrium constant for the reaction NH + O NO + H O in terms of K, K and K will be (a) K, K, K (b) K K /K (c) KK K. If K p for a reaction, (d) KK K A(g) + B(g) C(g) + D(g) is 0.05 atm at 000 K. The equilibrium constant K c in terms of R will be given by Page No.:

4 (a) 5 0 R (b) 5 0 R (c) R (d) 5 0 R. 8 moles of a gas AB are introduced into a.0 dm vessel. It dissociates according to the equation, AB (g) A (g) +B (g). At equilibrium moles of A are found to be present. The equilibrium constant of the reaction is (a) mole L (b) mole L (c) 6 mole L (d) 7 mole L 4. A (g) and B (g) react to form AB(g) according to the reaction, A (g) + B (g) AB(g). The partial pressure of A (g), B (g) and AB(g) are observed to be 0. atm, 0. atm and 0. atm respectively. When volume of container is made half of the initial volume, of partial pressures of A (g) and AB(g) becomes 0. atm and 0.6 atm respectively. The partial pressure of B (g) in the new equilibrium will be (a) 0. atm (c) 0.6 atm (b) 0.4 atm (d) 0.8 atm 5. The reaction quotient (Q) for the reaction, N (g) + H (g) NH (g) is given by [NH ] Q ==. The reaction will be proceed [N ][H ] from right to left if (K c = equilibrium constant) (a) Q = K c (b) Q < K c (c) Q > K c (d) Q = 0 6. When mole of pure ethyl alcohol (C OH) is mixed with mole of acetic acid at 5 C, the equilibrium mixture contains mole each of ester and water C OH(l) + CH COOH(l) = CH COOC (l) + H O The G for the reaction at 98 K -4-5 (a) is +45 J (b) is 4 J (c) is 440 J (d) cannot be calculated from the data provided 7. Substances A and B react according to an hypothetical reaction, A + B C. If G = 000 cal/mole. The equilibrium constant for the above reaction would be (T = 00 K) (a) 0 0 (b) 0 (c) 0 0 (d) In the thermal decomposition of potassium chlorate in a closed container given as, KClO (g) KCl(s) + O (g), law of mass action: (a) Cannot be applied (b) Can be applied (c) Can be applied at low temperature (d) Can be applied at high temperature and pressure 9. The yield of product in the reaction would be higher at, A (g) + B(g) C(g) + Q kj: (a) High temperature and high pressure (b) High temperature and low pressure (c) Low temperature and high pressure (d) Low temperature and low pressure 40. HI was heated in a sealed tube at 440 C till the equilibrium was reached, HI was found to be % decomposed. The equilibrium constant for dissociation is : (a) 0.8 (b) (c) (d).99 Page No.: 4

5 ANSWER. B. D. A 4. B. A 5. C 4. B 6. C 5. B 7. D 6. B 8. B 7. B 9. C 8. D 40. C 9. A 0. C. C. B. D 4. D 5. A 6. B 7. A 8. D 9. A 0. A. A. A. A 4. A 5. B 6. D 7. B 8. B 9. D 0. B. D. D Page No.: 5