Equilibrium Review - Chemistry 4U 1. When dinitrogen tetroxide gas N2O4 (g), is placed in a sealed container at 100°C, it decomposes into nitrogen dioxide gas, NO2 (g), according to the following balanced equation: N2O4 (g)
⇌
2 NO2 (g)
A laboratory technician places 0.25mol of dinitrogen tetroxide gas in a 1.0L closed container. At equilibrium, the concentration of nitrogen dioxide gas is 0.25mol/L. Use an ICE table to determine the equilibrium concentration of dinitrogen tetroxide gas.
2. At 35°C, 3.00mol of pure nitrosyl chloride gas, NOCl (g), is contained in a sealed 3.00L flask. The nitrosyl chloride gas decomposes to nitric oxide gas, NO (g), and chlorine gas until equilibrium is reached. 2 NOCl (g)
⇌
2 NO (g)
+
Cl2 (g)
At equilibrium, the concentration of nitric oxide gas is 0.043 mol/L. Use an ICE table to determine the equilibrium concentrations of nitrosyl chloride chloride gas and chlorine gas under the conditions used.
3. Calculate the pH of a 0.85mol/L solution of sodium hypochlorite, NaClO. (aq)
4. Will a precipitate form in an aqueous solution in which the concentration of copper (I) nitrate, CuNO3 (aq), is 0.015mol/L and the concentration of potassium iodide is 0.075mol/L?
5. Will a precipitate form is a student mixes 100.0mL of an aqueous solution of 0.100mol/L calcium chloride, CaCl2, with 100.0mL of an aqueous solution os 0.0400mol/L sodium sulfate, Na2SO4 (aq)? If so, identify the precipitate.
6. In a 250mL sealed container at 150°C, 0.50mol of both iodine gas, I2 (g), and bromine gas, Br2 (g), are mixed and allowed to react until they form an equilibrium with iodine monobromide gas, IBr. The equilibrium content for this reaction is 1.2 x 102. What are the equilibrium concentrations for iodine gas and bromine gas?
7. In a 2.00L reaction vessel at 440°C, hydrogen gas and iodine vapour form gaseous hydrogen iodide. The equilibrium constant is 49.7. Determine the equilibrium concentrations for all entities if 4.00mol of hydrogen gas and 1.99mol of iodine vapour are combined and the equilibrium concentration of hydrogen gas 1.07mol/L.
8. Write the acid ionization content equations for the following acid at equilibrium: HNO2
9. What is the pH of a 6.18 x 10 ^ -3 mol/L solution of hydrocyanic acid, HCN (aq)?
10. What is the pH of a 0.10 mol/L solution of nitrous acid, HNO2 (aq)?
11. Cyclopropane gas, C3H6 (g) will spontaneously undergo isomerization to form propene gas, C3H6 (g). If 2.50mol of cyclopropane is placed in a sealed 0.500L container, it will come to equilibrium with its isomer, propene. The value of the equilibrium constant, K, for this chemical system is 5.6. Determine the concentration of each gas at equilibrium.
12. If 0.200mol of hydrogen gas and 0.200mol of iodine gas are placed in a 1.00L sealed flask, an equilibrium system will be established with hydrogen iodine gas. Determine the concentration of all gases at SATP, given that the equilibrium constant is 49.5.
13. The following balanced chemical equation represents a chemical system at equilibrium: C2H4 (g) colourless
+
Br2 (g) brown
a) What visual changes will you see at equilibrium?
b) What is occurring at the molecular level?
c) Is the equilibrium static or dynamic?
⇌
C2H4Br2 (g) colourless
14. In a saturated solution of calcium phosphate, Ca3(PO4)2, at 25°C, the concentrations of the calcium ions and phosphate ions are 4.53 x 10 ^ -7 mol/L and 3.02 x 10 ^ -7 mol/L, respectively. Calculate the Ksp of calcium phosphate.
15. Calculate the pOH of a solution that has a pH of 4.
16. Calculate the pH with a solution with a pOH of 2.41. Is this solution acidic, basic or neutral?
17. A hydrochloric acid solution has a concentration of 0.0700mol/L. Calculate [OH-]
18. When heated, solid silver oxide, Ag2O(s), will decompose into silver metal, Ag(s), and oxygen gas. In a sealed vessel, the chemical system will form an equilibrium with an equilibrium constant, K, of 2.5 X 10 ^ -3. a) Write the equilibrium constant equation
b) When the instantaneous concentration of oxygen gas is 5.0 x 10 ^ -2 mol/L, is the chemical system at equilibrium? If not, in which direction will if shift to reach equilibrium
19. Calculate the molar solubility of silver iodide, AgI(s), at 25°C. Its Ksp value at this temperature is 8.5 x 10 ^ -17.
20. Determine Kb for the ethanoate ion, C2H3O2 -
21. Calculate the pH of a 0.20 mol/L solution of a base, where Kb = 3.82 x 10 ^ -10
22. Determine the pH of a 4.5 mol/L solution of hydrazine
23. A buffer solution contains 2.250mol/L ethnic acid, HC2H3O2 (aq). (Ka = 1.8 x 10 ^ -5) and 2.250mol/L sodium ethanoate, NaC2H3O2 (aq). Calculate the pH of this buffer solution.
24. A buffer contains 0.10mol/L hydrofluoric acid, (Ka = 6.6 x 10 ^ -4) and 0.10mol/L fluoride ions. Calculate the pH of the buffer solution.
25. The following balanced chemical equation represents a reaction at equilibrium: C2H4
+
H2
⇌
C2H6
+
energy
Predict how the equilibrium might respond to the following changes. Explain your answers. a) The volume of the container is decreased b) The temperature of the container is increased c) The concentration of C2H6 is decreased by removing the product d) More hydrogen gas is added
26. Calculate the pH of a solution with an [H+] of 1.8 x 10^ -9
27. Calculate the pH and the pOH of a solution in which [OH-] is 1.0 mol/L
28. The value of Ka for the ammonium ion, NH4, is 5.8 x 10 ^ -10. What is the value of the base ionization constant, Kb, for ammonia, NH3, at SATP
29. Calculate the percent ionization of the 0.050 mol/L solution of propanoic acid, HC3H5O2, with a pH of 2.78.
30. A 0.100 mol/L solution of hydrofluoric acid has a percent ionization 7,8%. Calculate the Ka for hydrofluoric acid.
31. In a sealed, rigid container, nitrogen dioxide gas, NO2 (g), is in equilibrium with dinitrogen tetroxide gas, N2H4 (g): K = 1.15 at 55°C 2NO2 (g)
⇌
N2H4 (g)
Find the equilibrium concentration of gaseous nitrogen dioxide and dinitrogen tetroxide if the initial concentration of nitrogen dioxide gas is 0.850M
32. A lab technician places 12.0mol of sulphur trioxide gas into a 3.0L sealed, rigid container. The sulphur trioxide gas dissociates into gaseous sulphur dioxide and oxygen gas until equilibrium is reached and 3.0mol of sulphur dioxide is present. Calculate the equilibrium constant.
33. Calculate the pH of a 0.525mol/L solution of ammonium chloride, NH4Cl (aq). (The Kb for ammonia NH3 is 1.8 x 10 ^ -5)
34. The Ksp of silver chloride, AgCl, is 1.8 x 10 ^ - 10 at 25°C. a) What is the molar solubility of solid silver chloride in pure water?
b) What is the molar solubility of solid silver chloride in 0.10mol/L aqueous solution of sodium chloride?
c) Compare your answers in a and b and explain if they can make sense
35. Predict whether a solution of copper (II) oxide, CuO, will be acidic, basic or neutral. Write a hydrolysis equation to support your answer.
36. A solution is made by bubbling nitrogen dioxide gas, NO2, into water. Predict whether the solution will be acidic, basic or neutral.
37. Calculate the molar solubility of solid zinc hydroxide, Zn(OH)2 at 25°C.
38. A student adds 100.0mL of 4.0 x 10 ^ -4 mol/L magnesium nitrate Mg(NO3)2 (aq) solution to 100.0mL of 2.0 x 10 ^ -3 mol/L sodium hydroxide, NaOH (aq), solution. Will a precipitate form? Justify your answer.
39. Calculate the [H+] and [OH-] in a 0.00100mol/L solution of potassium hydroxide, KOH (aq)
40. Calculate the pH of a 2.00L solution prepared by dissolving 0.042mol of strontium hydroxide, Sr(OH)2 in water.