20 A sample of solid potassium nitrate is placed in water Th

_____20. A sample of solid potassium nitrate is placed in water. The solid potassium nitrate comes to equilibrium with its dissolved ions by the endothermic process shown below. Which of the following changes to the system would increase the concentration of potassium ions at equilibrium?

KNO₃(s) K⁺ + NO₃^-  

A. The volume of the solution is increased

B. The volume of the solution is decreased

C. Additional solid KNO₃ is added to the solution

D. The temperature of the solution is increased

E. The temperature of the solution is decreased

_____21. Citric acid, H₃C₆H₅O₇, can give up three hydrogen ions in solution. The three dissociation reactions are listed below. Which of the following expressions gives the equilibrium constant for this reaction:   H₃C₆H₅O₇ 3H⁺   + C₆H₅O₇^3-

H₃C₆H₅O₇ H⁺ + H₂C₆H₅O₇^-                     K₁ = X

H₂C₆H₅O₇^- H⁺ + HC₆H₅O₇^2-                     K₂ = Y

HC₆H₅O₇^2- H⁺ + C₆H₅O₇^3-                       K₃ = Z

A. XYZ

B. XY/Z

C. X/YZ

D. Z/XY

E. 1/XYZ

_____22. A sealed isothermal container initially contained 2 moles of CO gas and 3 moles of H₂ gas. At equilibrium, there was found to be 1 mole of CH₃OH in the container. What is the total number of moles of gas present in the container at equilibrium if this is the reaction that occurred?

CO(g) + 2H₂(g) CH₃OH(g)

A. 1

B. 2

C. 3

D. 4

E. 5

Solution

C. Additional solid KNO₃ is added to the solution

D. The temperature of the solution is increased

21.H₃C₆H₅O₇ 3H⁺   + C₆H₅O₇^3-

      K   = [H^+][C6H5O7^3-]/[H3C6H5O7]

H₃C₆H₅O₇ H⁺ + H₂C₆H₅O₇^-                     K₁ = X

         K1   =[ H⁺ ] [H₂C₆H₅O₇^-]/[H₃C₆H₅O₇]

H₂C₆H₅O₇^- H⁺ + HC₆H₅O₇^2-                     K₂ = Y

    K2   = [ H⁺] [HC₆H₅O₇^2- ]/[H₂C₆H₅O₇^-]

HC₆H₅O₇^2- H⁺ + C₆H₅O₇^3-                       K₃ = Z

    K3    =[ H⁺ ] [C₆H₅O₇^3-]/[HC₆H₅O₇^2-]

K1K2K3 =   [ H⁺ ] [H₂C₆H₅O₇^-]/[H₃C₆H₅O₇] * [ H⁺] [HC₆H₅O₇^2- ]/[H₂C₆H₅O₇^-] *[ H⁺ ] [C₆H₅O₇^3-]/[HC₆H₅O₇^2-]

K1K2K3    = [H^+]^3[C6H5O7^3-]/[H3C6H5O7]

XYZ        = [H^+]^3[C6H5O7^3-]/[H3C6H5O7]

22.

          CO(g) + 2H₂(g) CH₃OH(g)

I           2           3                      0

C       -1        -2*1                      1

E       1           1                          1

    Kc    = [CH3OH]/[CO[H2]^2

    Kc   = 1/1*(1)^2

   Kc   = 1

A.1