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Chemistry · Textbook solutions

Equilibrium

Every solved example, exercise, and miscellaneous question — in the order the textbook teaches them. · 99 questions

Worked Examples

28 q

Solved Examples

Worked · 28
  1. Eg 6.1
    The following concentrations were obtained for the formation of NH3\text{NH}_3 from N2\text{N}_2 and H2\text{H}_2 at equilibrium at 500 K. [N2]=1.5×10−2 M[\text{N}_2] = 1.5 \times 10^{-2}\,\text{M}, [H2]=3.0×10−2 M[\text{H}_2] = 3.0 \times 10^{-2}\,\text{M} and [NH3]=1.2×10−2 M[\text{NH}_3] = 1.2 \times 10^{-2}\,\text{M}. Calculate equilibrium constant.
  2. Eg 6.2
    At equilibrium, the concentrations of N2=3.0×10−3 M\text{N}_2 = 3.0 \times 10^{-3}\,\text{M}, O2=4.2×10−3 M\text{O}_2 = 4.2 \times 10^{-3}\,\text{M} and NO=2.8×10−3 M\text{NO} = 2.8 \times 10^{-3}\,\text{M} in a sealed vessel at 800 K. What will be KcK_c for the reaction N2(g)+O2(g)⇌2NO(g)\text{N}_2(g) + \text{O}_2(g) \rightleftharpoons 2\text{NO}(g)
  3. Eg 6.3
    PCl5\text{PCl}_5, PCl3\text{PCl}_3 and Cl2\text{Cl}_2 are at equilibrium at 500 K and having concentration 1.59 M1.59\,\text{M} PCl3\text{PCl}_3, 1.59 M1.59\,\text{M} Cl2\text{Cl}_2 and 1.41 M1.41\,\text{M} PCl5\text{PCl}_5. Calculate KcK_c for the reaction, PCl5⇌PCl3+Cl2\text{PCl}_5 \rightleftharpoons \text{PCl}_3 + \text{Cl}_2
  4. Eg 6.4
    The value of Kc=4.24K_c = 4.24 at 800 K for the reaction, CO(g)+H2O(g)⇌CO2(g)+H2(g)\text{CO}(g) + \text{H}_2\text{O}(g) \rightleftharpoons \text{CO}_2(g) + \text{H}_2(g) Calculate equilibrium concentrations of CO2\text{CO}_2, H2\text{H}_2, CO\text{CO} and H2O\text{H}_2\text{O} at 800 K, if only CO\text{CO} and H2O\text{H}_2\text{O} are present initially at concentrations of 0.10 M0.10\,\text{M} each.
  5. Eg 6.5
    For the equilibrium, 2NOCl(g)⇌2NO(g)+Cl2(g)2\text{NOCl}(g) \rightleftharpoons 2\text{NO}(g) + \text{Cl}_2(g) the value of the equilibrium constant, KcK_c is 3.75×10−63.75 \times 10^{-6} at 1069 K. Calculate the KpK_p for the reaction at this temperature?
  6. Eg 6.6
    The value of KpK_p for the reaction, CO2(g)+C(s)⇌2CO(g)\text{CO}_2(g) + \text{C}(s) \rightleftharpoons 2\text{CO}(g) is 3.0 at 1000 K. If initially pCO2=0.48 barp_{\text{CO}_2} = 0.48\,\text{bar} and pCO=0 barp_{\text{CO}} = 0\,\text{bar} and pure graphite is present, calculate the equilibrium partial pressures of CO\text{CO} and CO2\text{CO}_2.
  7. Eg 6.7
    The value of KcK_c for the reaction 2A⇌B+C2\text{A} \rightleftharpoons \text{B} + \text{C} is 2×10−32 \times 10^{-3}. At a given time, the composition of reaction mixture is [A]=[B]=[C]=3×10−4 M[\text{A}] = [\text{B}] = [\text{C}] = 3 \times 10^{-4}\,\text{M}. In which direction the reaction will proceed?
  8. Eg 6.8
    13.8 g13.8\,\text{g} of N2O4\text{N}_2\text{O}_4 was placed in a 1 L1\,\text{L} reaction vessel at 400 K and allowed to attain equilibrium N2O4(g)⇌2NO2(g)\text{N}_2\text{O}_4(g) \rightleftharpoons 2\text{NO}_2(g) The total pressure at equilibrium was found to be 9.15 bar9.15\,\text{bar}. Calculate KcK_c, KpK_p and partial pressure at equilibrium.
  9. Eg 6.9
    3.00 mol3.00\,\text{mol} of PCl5\text{PCl}_5 kept in 1 L1\,\text{L} closed reaction vessel was allowed to attain equilibrium at 380 K. Calculate composition of the mixture at equilibrium. Kc=1.80K_c = 1.80
  10. Eg 6.10
    The value of ΔG⊖\Delta G^\ominus for the phosphorylation of glucose in glycolysis is 13.8 kJ/mol13.8\,\text{kJ/mol}. Find the value of KcK_c at 298 K.
  11. Eg 6.11
    Hydrolysis of sucrose gives, Sucrose + H2O⇌+\ \text{H}_2\text{O} \rightleftharpoons Glucose ++ Fructose Equilibrium constant KcK_c for the reaction is 2×10132 \times 10^{13} at 300 K. Calculate ΔG⊖\Delta G^\ominus at 300 K.
  12. Eg 6.12
    What will be the conjugate bases for the following Brönsted acids: HF\text{HF}, H2SO4\text{H}_2\text{SO}_4 and HCO3−\text{HCO}_3^-?
  13. Eg 6.13
    Write the conjugate acids for the following Brönsted bases: NH2−\text{NH}_2^-, NH3\text{NH}_3 and HCOO−\text{HCOO}^-.
  14. Eg 6.14
    The species: H2O\text{H}_2\text{O}, HCO3−\text{HCO}_3^-, HSO4−\text{HSO}_4^- and NH3\text{NH}_3 can act both as Bronsted acids and bases. For each case give the corresponding conjugate acid and conjugate base.
  15. Eg 6.15
    Classify the following species into Lewis acids and Lewis bases and show how these act as such: (a) HO−\text{HO}^- (b) F−\text{F}^- (c) H+\text{H}^+ (d) BCl3\text{BCl}_3
  16. Eg 6.16
    The concentration of hydrogen ion in a sample of soft drink is 3.8×10−3 M3.8 \times 10^{-3}\,\text{M}. What is its pH?
  17. Eg 6.17
    Calculate pH of a 1.0×10−8 M1.0 \times 10^{-8}\,\text{M} solution of HCl\text{HCl}.
  18. Eg 6.18
    The ionization constant of HF\text{HF} is 3.2×10−43.2 \times 10^{-4}. Calculate the degree of dissociation of HF\text{HF} in its 0.02 M0.02\,\text{M} solution. Calculate the concentration of all species present (H3O+\text{H}_3\text{O}^+, F−\text{F}^- and HF\text{HF}) in the solution and its pH.
  19. Eg 6.19
    The pH of 0.1 M0.1\,\text{M} monobasic acid is 4.50. Calculate the concentration of species H+\text{H}^+, A−\text{A}^- and HA\text{HA} at equilibrium. Also, determine the value of KaK_a and pKa\text{p}K_a of the monobasic acid.
  20. Eg 6.20
    Calculate the pH of 0.08 M0.08\,\text{M} solution of hypochlorous acid, HOCl\text{HOCl}. The ionization constant of the acid is 2.5×10−52.5 \times 10^{-5}. Determine the percent dissociation of HOCl\text{HOCl}.
  21. Eg 6.21
    The pH of 0.004 M0.004\,\text{M} hydrazine solution is 9.7. Calculate its ionization constant KbK_b and pKb\text{p}K_b.
  22. Eg 6.22
    Calculate the pH of the solution in which 0.2 M0.2\,\text{M} NH4Cl\text{NH}_4\text{Cl} and 0.1 M0.1\,\text{M} NH3\text{NH}_3 are present. The pKb\text{p}K_b of ammonia solution is 4.75.
  23. Eg 6.23
    Determine the degree of ionization and pH of a 0.05 M0.05\,\text{M} of ammonia solution. The ionization constant of ammonia can be taken from Table 6.7. Also, calculate the ionization constant of the conjugate acid of ammonia.
  24. Eg 6.24
    Calculate the pH of a 0.10 M0.10\,\text{M} ammonia solution. Calculate the pH after 50.0 mL50.0\,\text{mL} of this solution is treated with 25.0 mL25.0\,\text{mL} of 0.10 M0.10\,\text{M} HCl\text{HCl}. The dissociation constant of ammonia, Kb=1.77×10−5K_b = 1.77 \times 10^{-5}
  25. Eg 6.25
    The pKa\text{p}K_a of acetic acid and pKb\text{p}K_b of ammonium hydroxide are 4.76 and 4.75 respectively. Calculate the pH of ammonium acetate solution.
  26. Eg 6.26
    Calculate the solubility of A2X3\text{A}_2\text{X}_3 in pure water, assuming that neither kind of ion reacts with water. The solubility product of A2X3\text{A}_2\text{X}_3, Ksp=1.1×10−23K_{sp} = 1.1 \times 10^{-23}.
  27. Eg 6.27
    The values of KspK_{sp} of two sparingly soluble salts Ni(OH)2\text{Ni(OH)}_2 and AgCN\text{AgCN} are 2.0×10−152.0 \times 10^{-15} and 6×10−176 \times 10^{-17} respectively. Which salt is more soluble? Explain.
  28. Eg 6.28
    Calculate the molar solubility of Ni(OH)2\text{Ni(OH)}_2 in 0.10 M0.10\,\text{M} NaOH\text{NaOH}. The ionic product of Ni(OH)2\text{Ni(OH)}_2 is 2.0×10−152.0 \times 10^{-15}.

Exercises

71 q
  1. Ex 6.1
    A liquid is in equilibrium with its vapour in a sealed container at a fixed temperature. The volume of the container is suddenly increased. a) What is the initial effect of the change on vapour pressure? b) How do rates of evaporation and condensation change initially? c) What happens when equilibrium is restored finally and what will be the final vapour pressure?
  2. Ex 6.2
    What is KcK_c for the following equilibrium when the equilibrium concentration of each substance is: [SO2]=0.60 M[\text{SO}_2] = 0.60\,\text{M}, [O2]=0.82 M[\text{O}_2] = 0.82\,\text{M} and [SO3]=1.90 M[\text{SO}_3] = 1.90\,\text{M}? 2SO2(g)+O2(g)⇌2SO3(g)2\text{SO}_2(g) + \text{O}_2(g) \rightleftharpoons 2\text{SO}_3(g)
  3. Ex 6.3
    At a certain temperature and total pressure of 105 Pa10^5\,\text{Pa}, iodine vapour contains 40% by volume of I\text{I} atoms I2(g)⇌2I(g)\text{I}_2(g) \rightleftharpoons 2\text{I}(g) Calculate KpK_p for the equilibrium.
  4. Ex 6.4
    Write the expression for the equilibrium constant, KcK_c for each of the following reactions: (i) 2NOCl(g)⇌2NO(g)+Cl2(g)2\text{NOCl}(g) \rightleftharpoons 2\text{NO}(g) + \text{Cl}_2(g) (ii) 2Cu(NO3)2(s)⇌2CuO(s)+4NO2(g)+O2(g)2\text{Cu(NO}_3)_2(s) \rightleftharpoons 2\text{CuO}(s) + 4\text{NO}_2(g) + \text{O}_2(g) (iii) CH3COOC2H5(aq)+H2O(l)⇌CH3COOH(aq)+C2H5OH(aq)\text{CH}_3\text{COOC}_2\text{H}_5(aq) + \text{H}_2\text{O}(l) \rightleftharpoons \text{CH}_3\text{COOH}(aq) + \text{C}_2\text{H}_5\text{OH}(aq) (iv) Fe3+(aq)+3OH−(aq)⇌Fe(OH)3(s)\text{Fe}^{3+}(aq) + 3\text{OH}^-(aq) \rightleftharpoons \text{Fe(OH)}_3(s) (v) I2(s)+5F2⇌2IF5\text{I}_2(s) + 5\text{F}_2 \rightleftharpoons 2\text{IF}_5
  5. Ex 6.5
    Find out the value of KcK_c for each of the following equilibria from the value of KpK_p: (i) 2NOCl(g)⇌2NO(g)+Cl2(g)2\text{NOCl}(g) \rightleftharpoons 2\text{NO}(g) + \text{Cl}_2(g); Kp=1.8×10−2K_p = 1.8 \times 10^{-2} at 500 K (ii) CaCO3(s)⇌CaO(s)+CO2(g)\text{CaCO}_3(s) \rightleftharpoons \text{CaO}(s) + \text{CO}_2(g); Kp=167K_p = 167 at 1073 K
  6. Ex 6.6
    For the following equilibrium, Kc=6.3×1014K_c = 6.3 \times 10^{14} at 1000 K NO(g)+O3(g)⇌NO2(g)+O2(g)\text{NO}(g) + \text{O}_3(g) \rightleftharpoons \text{NO}_2(g) + \text{O}_2(g) Both the forward and reverse reactions in the equilibrium are elementary bimolecular reactions. What is KcK_c for the reverse reaction?
  7. Ex 6.7
    Explain why pure liquids and solids can be ignored while writing the equilibrium constant expression?
  8. Ex 6.8
    Reaction between N2\text{N}_2 and O2\text{O}_2 takes place as follows: 2N2(g)+O2(g)⇌2N2O(g)2\text{N}_2(g) + \text{O}_2(g) \rightleftharpoons 2\text{N}_2\text{O}(g) If a mixture of 0.482 mol0.482\,\text{mol} N2\text{N}_2 and 0.933 mol0.933\,\text{mol} of O2\text{O}_2 is placed in a 10 L10\,\text{L} reaction vessel and allowed to form N2O\text{N}_2\text{O} at a temperature for which Kc=2.0×10−37K_c = 2.0 \times 10^{-37}, determine the composition of equilibrium mixture.
  9. Ex 6.9
    Nitric oxide reacts with Br2\text{Br}_2 and gives nitrosyl bromide as per reaction given below: 2NO(g)+Br2(g)⇌2NOBr(g)2\text{NO}(g) + \text{Br}_2(g) \rightleftharpoons 2\text{NOBr}(g) When 0.087 mol0.087\,\text{mol} of NO\text{NO} and 0.0437 mol0.0437\,\text{mol} of Br2\text{Br}_2 are mixed in a closed container at constant temperature, 0.0518 mol0.0518\,\text{mol} of NOBr\text{NOBr} is obtained at equilibrium. Calculate equilibrium amount of NO\text{NO} and Br2\text{Br}_2.
  10. Ex 6.10
    At 450 K, Kp=2.0×1010/barK_p = 2.0 \times 10^{10}/\text{bar} for the given reaction at equilibrium. 2SO2(g)+O2(g)⇌2SO3(g)2\text{SO}_2(g) + \text{O}_2(g) \rightleftharpoons 2\text{SO}_3(g) What is KcK_c at this temperature?
  11. Ex 6.11
    A sample of HI(g)\text{HI}(g) is placed in flask at a pressure of 0.2 atm0.2\,\text{atm}. At equilibrium the partial pressure of HI(g)\text{HI}(g) is 0.04 atm0.04\,\text{atm}. What is KpK_p for the given equilibrium? 2HI(g)⇌H2(g)+I2(g)2\text{HI}(g) \rightleftharpoons \text{H}_2(g) + \text{I}_2(g)
  12. Ex 6.12
    A mixture of 1.57 mol1.57\,\text{mol} of N2\text{N}_2, 1.92 mol1.92\,\text{mol} of H2\text{H}_2 and 8.13 mol8.13\,\text{mol} of NH3\text{NH}_3 is introduced into a 20 L20\,\text{L} reaction vessel at 500 K. At this temperature, the equilibrium constant, KcK_c for the reaction N2(g)+3H2(g)⇌2NH3(g)\text{N}_2(g) + 3\text{H}_2(g) \rightleftharpoons 2\text{NH}_3(g) is 1.7×1021.7 \times 10^2. Is the reaction mixture at equilibrium? If not, what is the direction of the net reaction?
  13. Ex 6.13
    The equilibrium constant expression for a gas reaction is, Kc=[NH3]4[O2]5[NO]4[H2O]6K_c = \dfrac{[\text{NH}_3]^4[\text{O}_2]^5}{[\text{NO}]^4[\text{H}_2\text{O}]^6} Write the balanced chemical equation corresponding to this expression.
  14. Ex 6.14
    One mole of H2O\text{H}_2\text{O} and one mole of CO\text{CO} are taken in 10 L10\,\text{L} vessel and heated to 725 K. At equilibrium 40% of water (by mass) reacts with CO\text{CO} according to the equation, H2O(g)+CO(g)⇌H2(g)+CO2(g)\text{H}_2\text{O}(g) + \text{CO}(g) \rightleftharpoons \text{H}_2(g) + \text{CO}_2(g) Calculate the equilibrium constant for the reaction.
  15. Ex 6.15
    At 700 K, equilibrium constant for the reaction: H2(g)+I2(g)⇌2HI(g)\text{H}_2(g) + \text{I}_2(g) \rightleftharpoons 2\text{HI}(g) is 54.8. If 0.5 mol L−10.5\,\text{mol L}^{-1} of HI(g)\text{HI}(g) is present at equilibrium at 700 K, what are the concentration of H2(g)\text{H}_2(g) and I2(g)\text{I}_2(g) assuming that we initially started with HI(g)\text{HI}(g) and allowed it to reach equilibrium at 700 K?
  16. Ex 6.16
    What is the equilibrium concentration of each of the substances in the equilibrium when the initial concentration of ICl\text{ICl} was 0.78 M0.78\,\text{M}? 2ICl(g)⇌I2(g)+Cl2(g)2\text{ICl}(g) \rightleftharpoons \text{I}_2(g) + \text{Cl}_2(g); Kc=0.14K_c = 0.14
  17. Ex 6.17
    Kp=0.04 atmK_p = 0.04\,\text{atm} at 899 K for the equilibrium shown below. What is the equilibrium concentration of C2H6\text{C}_2\text{H}_6 when it is placed in a flask at 4.0 atm4.0\,\text{atm} pressure and allowed to come to equilibrium? C2H6(g)⇌C2H4(g)+H2(g)\text{C}_2\text{H}_6(g) \rightleftharpoons \text{C}_2\text{H}_4(g) + \text{H}_2(g)
  18. Ex 6.18
    Ethyl acetate is formed by the reaction between ethanol and acetic acid and the equilibrium is represented as: CH3COOH(l)+C2H5OH(l)⇌CH3COOC2H5(l)+H2O(l)\text{CH}_3\text{COOH}(l) + \text{C}_2\text{H}_5\text{OH}(l) \rightleftharpoons \text{CH}_3\text{COOC}_2\text{H}_5(l) + \text{H}_2\text{O}(l) (i) Write the concentration ratio (reaction quotient), QcQ_c, for this reaction (note: water is not in excess and is not a solvent in this reaction) (ii) At 293 K, if one starts with 1.00 mol1.00\,\text{mol} of acetic acid and 0.18 mol0.18\,\text{mol} of ethanol, there is 0.171 mol0.171\,\text{mol} of ethyl acetate in the final equilibrium mixture. Calculate the equilibrium constant. (iii) Starting with 0.5 mol0.5\,\text{mol} of ethanol and 1.0 mol1.0\,\text{mol} of acetic acid and maintaining it at 293 K, 0.214 mol0.214\,\text{mol} of ethyl acetate is found after sometime. Has equilibrium been reached?
  19. Ex 6.19
    A sample of pure PCl5\text{PCl}_5 was introduced into an evacuated vessel at 473 K. After equilibrium was attained, concentration of PCl5\text{PCl}_5 was found to be 0.5×10−1 mol L−10.5 \times 10^{-1}\,\text{mol L}^{-1}. If value of KcK_c is 8.3×10−38.3 \times 10^{-3}, what are the concentrations of PCl3\text{PCl}_3 and Cl2\text{Cl}_2 at equilibrium? PCl5(g)⇌PCl3(g)+Cl2(g)\text{PCl}_5(g) \rightleftharpoons \text{PCl}_3(g) + \text{Cl}_2(g)
  20. Ex 6.20
    One of the reaction that takes place in producing steel from iron ore is the reduction of iron(II) oxide by carbon monoxide to give iron metal and CO2\text{CO}_2. FeO(s)+CO(g)⇌Fe(s)+CO2(g)\text{FeO}(s) + \text{CO}(g) \rightleftharpoons \text{Fe}(s) + \text{CO}_2(g); Kp=0.265 atmK_p = 0.265\,\text{atm} at 1050 K What are the equilibrium partial pressures of CO\text{CO} and CO2\text{CO}_2 at 1050 K if the initial partial pressures are: pCO=1.4 atmp_{\text{CO}} = 1.4\,\text{atm} and pCO2=0.80 atmp_{\text{CO}_2} = 0.80\,\text{atm}?
  21. Ex 6.21
    Equilibrium constant, KcK_c for the reaction N2(g)+3H2(g)⇌2NH3(g)\text{N}_2(g) + 3\text{H}_2(g) \rightleftharpoons 2\text{NH}_3(g) at 500 K is 0.061 At a particular time, the analysis shows that composition of the reaction mixture is 3.0 mol L−13.0\,\text{mol L}^{-1} N2\text{N}_2, 2.0 mol L−12.0\,\text{mol L}^{-1} H2\text{H}_2 and 0.5 mol L−10.5\,\text{mol L}^{-1} NH3\text{NH}_3. Is the reaction at equilibrium? If not in which direction does the reaction tend to proceed to reach equilibrium?
  22. Ex 6.22
    Bromine monochloride, BrCl\text{BrCl} decomposes into bromine and chlorine and reaches the equilibrium: 2BrCl(g)⇌Br2(g)+Cl2(g)2\text{BrCl}(g) \rightleftharpoons \text{Br}_2(g) + \text{Cl}_2(g) for which Kc=32K_c = 32 at 500 K. If initially pure BrCl\text{BrCl} is present at a concentration of 3.3×10−3 mol L−13.3 \times 10^{-3}\,\text{mol L}^{-1}, what is its molar concentration in the mixture at equilibrium?
  23. Ex 6.23
    At 1127 K and 1 atm1\,\text{atm} pressure, a gaseous mixture of CO\text{CO} and CO2\text{CO}_2 in equilibrium with soild carbon has 90.55% CO\text{CO} by mass C(s)+CO2(g)⇌2CO(g)\text{C}(s) + \text{CO}_2(g) \rightleftharpoons 2\text{CO}(g) Calculate KcK_c for this reaction at the above temperature.
  24. Ex 6.24
    Calculate a) ΔG⊖\Delta G^\ominus and b) the equilibrium constant for the formation of NO2\text{NO}_2 from NO\text{NO} and O2\text{O}_2 at 298 K NO(g)+12O2(g)⇌NO2(g)\text{NO}(g) + \tfrac{1}{2}\text{O}_2(g) \rightleftharpoons \text{NO}_2(g) where ΔfG⊖(NO2)=52.0 kJ/mol\Delta_f G^\ominus(\text{NO}_2) = 52.0\,\text{kJ/mol} ΔfG⊖(NO)=87.0 kJ/mol\Delta_f G^\ominus(\text{NO}) = 87.0\,\text{kJ/mol} ΔfG⊖(O2)=0 kJ/mol\Delta_f G^\ominus(\text{O}_2) = 0\,\text{kJ/mol}
  25. Ex 6.25
    Does the number of moles of reaction products increase, decrease or remain same when each of the following equilibria is subjected to a decrease in pressure by increasing the volume? (a) PCl5(g)⇌PCl3(g)+Cl2(g)\text{PCl}_5(g) \rightleftharpoons \text{PCl}_3(g) + \text{Cl}_2(g) (b) CaO(s)+CO2(g)⇌CaCO3(s)\text{CaO}(s) + \text{CO}_2(g) \rightleftharpoons \text{CaCO}_3(s) (c) 3Fe(s)+4H2O(g)⇌Fe3O4(s)+4H2(g)3\text{Fe}(s) + 4\text{H}_2\text{O}(g) \rightleftharpoons \text{Fe}_3\text{O}_4(s) + 4\text{H}_2(g)
  26. Ex 6.26
    Which of the following reactions will get affected by increasing the pressure? Also, mention whether change will cause the reaction to go into forward or backward direction. (i) COCl2(g)⇌CO(g)+Cl2(g)\text{COCl}_2(g) \rightleftharpoons \text{CO}(g) + \text{Cl}_2(g) (ii) CH4(g)+2S2(g)⇌CS2(g)+2H2S(g)\text{CH}_4(g) + 2\text{S}_2(g) \rightleftharpoons \text{CS}_2(g) + 2\text{H}_2\text{S}(g) (iii) CO2(g)+C(s)⇌2CO(g)\text{CO}_2(g) + \text{C}(s) \rightleftharpoons 2\text{CO}(g) (iv) 2H2(g)+CO(g)⇌CH3OH(g)2\text{H}_2(g) + \text{CO}(g) \rightleftharpoons \text{CH}_3\text{OH}(g) (v) CaCO3(s)⇌CaO(s)+CO2(g)\text{CaCO}_3(s) \rightleftharpoons \text{CaO}(s) + \text{CO}_2(g) (vi) 4NH3(g)+5O2(g)⇌4NO(g)+6H2O(g)4\text{NH}_3(g) + 5\text{O}_2(g) \rightleftharpoons 4\text{NO}(g) + 6\text{H}_2\text{O}(g)
  27. Ex 6.27
    The equilibrium constant for the following reaction is 1.6×1051.6 \times 10^5 at 1024 K H2(g)+Br2(g)⇌2HBr(g)\text{H}_2(g) + \text{Br}_2(g) \rightleftharpoons 2\text{HBr}(g) Find the equilibrium pressure of all gases if 10.0 bar10.0\,\text{bar} of HBr\text{HBr} is introduced into a sealed container at 1024 K.
  28. Ex 6.28
    Dihydrogen gas is obtained from natural gas by partial oxidation with steam as per following endothermic reaction: CH4(g)+H2O(g)⇌CO(g)+3H2(g)\text{CH}_4(g) + \text{H}_2\text{O}(g) \rightleftharpoons \text{CO}(g) + 3\text{H}_2(g) (a) Write as expression for KpK_p for the above reaction. (b) How will the values of KpK_p and composition of equilibrium mixture be affected by (i) increasing the pressure (ii) increasing the temperature (iii) using a catalyst?
  29. Ex 6.29
    Describe the effect of: a) addition of H2\text{H}_2 b) addition of CH3OH\text{CH}_3\text{OH} c) removal of CO\text{CO} d) removal of CH3OH\text{CH}_3\text{OH} on the equilibrium of the reaction: 2H2(g)+CO(g)⇌CH3OH(g)2\text{H}_2(g) + \text{CO}(g) \rightleftharpoons \text{CH}_3\text{OH}(g)
  30. Ex 6.30
    At 473 K, equilibrium constant KcK_c for decomposition of phosphorus pentachloride, PCl5\text{PCl}_5 is 8.3×10−38.3 \times 10^{-3}. If decomposition is depicted as, PCl5(g)⇌PCl3(g)+Cl2(g)\text{PCl}_5(g) \rightleftharpoons \text{PCl}_3(g) + \text{Cl}_2(g) ΔrH⊖=124.0 kJ mol−1\Delta_r H^\ominus = 124.0\,\text{kJ mol}^{-1} a) write an expression for KcK_c for the reaction. b) what is the value of KcK_c for the reverse reaction at the same temperature? c) what would be the effect on KcK_c if (i) more PCl5\text{PCl}_5 is added (ii) pressure is increased (iii) the temperature is increased?
  31. Ex 6.31
    Dihydrogen gas used in Haber's process is produced by reacting methane from natural gas with high temperature steam. The first stage of two stage reaction involves the formation of CO\text{CO} and H2\text{H}_2. In second stage, CO\text{CO} formed in first stage is reacted with more steam in water gas shift reaction, CO(g)+H2O(g)⇌CO2(g)+H2(g)\text{CO}(g) + \text{H}_2\text{O}(g) \rightleftharpoons \text{CO}_2(g) + \text{H}_2(g) If a reaction vessel at 400 ∘C400\,^\circ\text{C} is charged with an equimolar mixture of CO\text{CO} and steam such that pCO=pH2O=4.0 barp_{\text{CO}} = p_{\text{H}_2\text{O}} = 4.0\,\text{bar}, what will be the partial pressure of H2\text{H}_2 at equilibrium? Kp=10.1K_p = 10.1 at 400 ∘C400\,^\circ\text{C}
  32. Ex 6.32
    Predict which of the following reaction will have appreciable concentration of reactants and products: a) Cl2(g)⇌2Cl(g)\text{Cl}_2(g) \rightleftharpoons 2\text{Cl}(g) Kc=5×10−39K_c = 5 \times 10^{-39} b) Cl2(g)+2NO(g)⇌2NOCl(g)\text{Cl}_2(g) + 2\text{NO}(g) \rightleftharpoons 2\text{NOCl}(g) Kc=3.7×108K_c = 3.7 \times 10^8 c) Cl2(g)+2NO2(g)⇌2NO2Cl(g)\text{Cl}_2(g) + 2\text{NO}_2(g) \rightleftharpoons 2\text{NO}_2\text{Cl}(g) Kc=1.8K_c = 1.8
  33. Ex 6.33
    The value of KcK_c for the reaction 3O2(g)⇌2O3(g)3\text{O}_2(g) \rightleftharpoons 2\text{O}_3(g) is 2.0×10−502.0 \times 10^{-50} at 25 ∘C25\,^\circ\text{C}. If the equilibrium concentration of O2\text{O}_2 in air at 25 ∘C25\,^\circ\text{C} is 1.6×10−21.6 \times 10^{-2}, what is the concentration of O3\text{O}_3?
  34. Ex 6.34
    The reaction, CO(g)+3H2(g)⇌CH4(g)+H2O(g)\text{CO}(g) + 3\text{H}_2(g) \rightleftharpoons \text{CH}_4(g) + \text{H}_2\text{O}(g) is at equilibrium at 1300 K in a 1 L1\,\text{L} flask. It also contain 0.30 mol0.30\,\text{mol} of CO\text{CO}, 0.10 mol0.10\,\text{mol} of H2\text{H}_2 and 0.02 mol0.02\,\text{mol} of H2O\text{H}_2\text{O} and an unknown amount of CH4\text{CH}_4 in the flask. Determine the concentration of CH4\text{CH}_4 in the mixture. The equilibrium constant, KcK_c for the reaction at the given temperature is 3.90.
  35. Ex 6.35
    What is meant by the conjugate acid-base pair? Find the conjugate acid/base for the following species: HNO2\text{HNO}_2, CN−\text{CN}^-, HClO4\text{HClO}_4, F−\text{F}^-, OH−\text{OH}^-, CO32−\text{CO}_3^{2-}, and S2−\text{S}^{2-}
  36. Ex 6.36
    Which of the followings are Lewis acids? H2O\text{H}_2\text{O}, BF3\text{BF}_3, H+\text{H}^+, and NH4+\text{NH}_4^+
  37. Ex 6.37
    What will be the conjugate bases for the Brönsted acids: HF\text{HF}, H2SO4\text{H}_2\text{SO}_4 and HCO3−\text{HCO}_3^-?
  38. Ex 6.39
    The species: H2O\text{H}_2\text{O}, HCO3−\text{HCO}_3^-, HSO4−\text{HSO}_4^- and NH3\text{NH}_3 can act both as Brönsted acids and bases. For each case give the corresponding conjugate acid and base.
  39. Ex 6.40
    Classify the following species into Lewis acids and Lewis bases and show how these act as Lewis acid/base: (a) OH−\text{OH}^- (b) F−\text{F}^- (c) H+\text{H}^+ (d) BCl3\text{BCl}_3.
  40. Ex 6.42
    The pH of a sample of vinegar is 3.76. Calculate the concentration of hydrogen ion in it.
  41. Ex 6.43
    The ionization constant of HF\text{HF}, HCOOH\text{HCOOH} and HCN\text{HCN} at 298 K are 6.8×10−46.8 \times 10^{-4}, 1.8×10−41.8 \times 10^{-4} and 4.8×10−94.8 \times 10^{-9} respectively. Calculate the ionization constants of the corresponding conjugate base.
  42. Ex 6.44
    The ionization constant of phenol is 1.0×10−101.0 \times 10^{-10}. What is the concentration of phenolate ion in 0.05 M0.05\,\text{M} solution of phenol? What will be its degree of ionization if the solution is also 0.01 M0.01\,\text{M} in sodium phenolate?
  43. Ex 6.45
    The first ionization constant of H2S\text{H}_2\text{S} is 9.1×10−89.1 \times 10^{-8}. Calculate the concentration of HS−\text{HS}^- ion in its 0.1 M0.1\,\text{M} solution. How will this concentration be affected if the solution is 0.1 M0.1\,\text{M} in HCl\text{HCl} also? If the second dissociation constant of H2S\text{H}_2\text{S} is 1.2×10−131.2 \times 10^{-13}, calculate the concentration of S2−\text{S}^{2-} under both conditions.
  44. Ex 6.46
    The ionization constant of acetic acid is 1.74×10−51.74 \times 10^{-5}. Calculate the degree of dissociation of acetic acid in its 0.05 M0.05\,\text{M} solution. Calculate the concentration of acetate ion in the solution and its pH.
  45. Ex 6.47
    It has been found that the pH of a 0.01 M0.01\,\text{M} solution of an organic acid is 4.15. Calculate the concentration of the anion, the ionization constant of the acid and its pKa\text{p}K_a.
  46. Ex 6.48
    Assuming complete dissociation, calculate the pH of the following solutions: (a) 0.003 M0.003\,\text{M} HCl\text{HCl} (b) 0.005 M0.005\,\text{M} NaOH\text{NaOH} (c) 0.002 M0.002\,\text{M} HBr\text{HBr} (d) 0.002 M0.002\,\text{M} KOH\text{KOH}
  47. Ex 6.49
    Calculate the pH of the following solutions: a) 2 g2\,\text{g} of TlOH\text{TlOH} dissolved in water to give 22 litre of solution. b) 0.3 g0.3\,\text{g} of Ca(OH)2\text{Ca(OH)}_2 dissolved in water to give 500 mL500\,\text{mL} of solution. c) 0.3 g0.3\,\text{g} of NaOH\text{NaOH} dissolved in water to give 200 mL200\,\text{mL} of solution. d) 1 mL1\,\text{mL} of 13.6 M13.6\,\text{M} HCl\text{HCl} is diluted with water to give 11 litre of solution.
  48. Ex 6.50
    The degree of ionization of a 0.1 M0.1\,\text{M} bromoacetic acid solution is 0.132. Calculate the pH of the solution and the pKa\text{p}K_a of bromoacetic acid.
  49. Ex 6.51
    The pH of 0.005 M0.005\,\text{M} codeine (C18H21NO3)(\text{C}_{18}\text{H}_{21}\text{NO}_3) solution is 9.95. Calculate its ionization constant and pKb\text{p}K_b.
  50. Ex 6.52
    What is the pH of 0.001 M0.001\,\text{M} aniline solution? The ionization constant of aniline can be taken from Table 6.7. Calculate the degree of ionization of aniline in the solution. Also calculate the ionization constant of the conjugate acid of aniline.
  51. Ex 6.53
    Calculate the degree of ionization of 0.05 M0.05\,\text{M} acetic acid if its pKa\text{p}K_a value is 4.74. How is the degree of dissociation affected when its solution also contains (a) 0.01 M0.01\,\text{M} (b) 0.1 M0.1\,\text{M} in HCl\text{HCl}?
  52. Ex 6.54
    The ionization constant of dimethylamine is 5.4×10−45.4 \times 10^{-4}. Calculate its degree of ionization in its 0.02 M0.02\,\text{M} solution. What percentage of dimethylamine is ionized if the solution is also 0.1 M0.1\,\text{M} in NaOH\text{NaOH}?
  53. Ex 6.55
    Calculate the hydrogen ion concentration in the following biological fluids whose pH are given below: (a) Human muscle-fluid, 6.83 (b) Human stomach fluid, 1.2 (c) Human blood, 7.38 (d) Human saliva, 6.4.
  54. Ex 6.56
    The pH of milk, black coffee, tomato juice, lemon juice and egg white are 6.8, 5.0, 4.2, 2.2 and 7.8 respectively. Calculate corresponding hydrogen ion concentration in each.
  55. Ex 6.57
    If 0.561 g0.561\,\text{g} of KOH\text{KOH} is dissolved in water to give 200 mL200\,\text{mL} of solution at 298 K. Calculate the concentrations of potassium, hydrogen and hydroxyl ions. What is its pH?
  56. Ex 6.58
    The solubility of Sr(OH)2\text{Sr(OH)}_2 at 298 K is 19.23 g/L19.23\,\text{g/L} of solution. Calculate the concentrations of strontium and hydroxyl ions and the pH of the solution.
  57. Ex 6.59
    The ionization constant of propanoic acid is 1.32×10−51.32 \times 10^{-5}. Calculate the degree of ionization of the acid in its 0.05 M0.05\,\text{M} solution and also its pH. What will be its degree of ionization if the solution is 0.01 M0.01\,\text{M} in HCl\text{HCl} also?
  58. Ex 6.60
    The pH of 0.1 M0.1\,\text{M} solution of cyanic acid (HCNO)(\text{HCNO}) is 2.34. Calculate the ionization constant of the acid and its degree of ionization in the solution.
  59. Ex 6.61
    The ionization constant of nitrous acid is 4.5×10−44.5 \times 10^{-4}. Calculate the pH of 0.04 M0.04\,\text{M} sodium nitrite solution and also its degree of hydrolysis.
  60. Ex 6.62
    A 0.02 M0.02\,\text{M} solution of pyridinium hydrochloride has pH=3.44\text{pH} = 3.44. Calculate the ionization constant of pyridine.
  61. Ex 6.63
    Predict if the solutions of the following salts are neutral, acidic or basic: NaCl\text{NaCl}, KBr\text{KBr}, NaCN\text{NaCN}, NH4NO3\text{NH}_4\text{NO}_3, NaNO2\text{NaNO}_2 and KF\text{KF}
  62. Ex 6.64
    The ionization constant of chloroacetic acid is 1.35×10−31.35 \times 10^{-3}. What will be the pH of 0.1 M0.1\,\text{M} acid and its 0.1 M0.1\,\text{M} sodium salt solution?
  63. Ex 6.65
    Ionic product of water at 310 K is 2.7×10−142.7 \times 10^{-14}. What is the pH of neutral water at this temperature?
  64. Ex 6.66
    Calculate the pH of the resultant mixtures: a) 10 mL10\,\text{mL} of 0.2 M0.2\,\text{M} Ca(OH)2+25 mL\text{Ca(OH)}_2 + 25\,\text{mL} of 0.1 M0.1\,\text{M} HCl\text{HCl} b) 10 mL10\,\text{mL} of 0.01 M0.01\,\text{M} H2SO4+10 mL\text{H}_2\text{SO}_4 + 10\,\text{mL} of 0.01 M0.01\,\text{M} Ca(OH)2\text{Ca(OH)}_2 c) 10 mL10\,\text{mL} of 0.1 M0.1\,\text{M} H2SO4+10 mL\text{H}_2\text{SO}_4 + 10\,\text{mL} of 0.1 M0.1\,\text{M} KOH\text{KOH}
  65. Ex 6.67
    Determine the solubilities of silver chromate, barium chromate, ferric hydroxide, lead chloride and mercurous iodide at 298 K from their solubility product constants given in Table 6.9. Determine also the molarities of individual ions.
  66. Ex 6.68
    The solubility product constant of Ag2CrO4\text{Ag}_2\text{CrO}_4 and AgBr\text{AgBr} are 1.1×10−121.1 \times 10^{-12} and 5.0×10−135.0 \times 10^{-13} respectively. Calculate the ratio of the molarities of their saturated solutions.
  67. Ex 6.69
    Equal volumes of 0.002 M0.002\,\text{M} solutions of sodium iodate and cupric chlorate are mixed together. Will it lead to precipitation of copper iodate? (For cupric iodate Ksp=7.4×10−8K_{sp} = 7.4 \times 10^{-8}).
  68. Ex 6.70
    The ionization constant of benzoic acid is 6.46×10−56.46 \times 10^{-5} and KspK_{sp} for silver benzoate is 2.5×10−132.5 \times 10^{-13}. How many times is silver benzoate more soluble in a buffer of pH 3.19\text{pH } 3.19 compared to its solubility in pure water?
  69. Ex 6.71
    What is the maximum concentration of equimolar solutions of ferrous sulphate and sodium sulphide so that when mixed in equal volumes, there is no precipitation of iron sulphide? (For iron sulphide, Ksp=6.3×10−18K_{sp} = 6.3 \times 10^{-18}).
  70. Ex 6.72
    What is the minimum volume of water required to dissolve 1 g1\,\text{g} of calcium sulphate at 298 K? (For calcium sulphate, KspK_{sp} is 9.1×10−69.1 \times 10^{-6}).
  71. Ex 6.73
    The concentration of sulphide ion in 0.1 M0.1\,\text{M} HCl\text{HCl} solution saturated with hydrogen sulphide is 1.0×10−19 M1.0 \times 10^{-19}\,\text{M}. If 10 mL10\,\text{mL} of this is added to 5 mL5\,\text{mL} of 0.04 M0.04\,\text{M} solution of the following: FeSO4\text{FeSO}_4, MnCl2\text{MnCl}_2, ZnCl2\text{ZnCl}_2 and CdCl2\text{CdCl}_2, in which of these solutions precipitation will take place?