Reversible reactions and dynamic equilibrium

9.Which of the following are features of a system at dynamic equilibrium? (select all that apply)

10.Match each term with its correct description.

11.For the reaction N₂(g) + 3H₂(g) ⇌ 2NH₃(g), what is the effect of increasing the pressure on the position of equilibrium?

12.A catalyst increases the rate of both the forward and reverse reactions equally, so it does not change the position of equilibrium.

13.For the reaction 2SO₂(g) + O₂(g) ⇌ 2SO₃(g), which changes would increase the yield of SO₃? (select all that apply)

14.Match each change to its effect on the equilibrium N₂(g) + 3H₂(g) ⇌ 2NH₃(g) (forward reaction exothermic).

15.For the reaction 2NO₂(g) ⇌ N₂O₄(g), the forward reaction is exothermic. What is the effect of increasing the temperature on the position of equilibrium?

16.In a reversible reaction, if the forward reaction is exothermic, the reverse reaction is endothermic.

17.Place the following steps in order to describe how the equilibrium N₂(g) + 3H₂(g) ⇌ 2NH₃(g) is established in a closed system, starting with only N₂ and H₂.

18.Which statement about the Haber process is correct?

19.For the reaction ICl(l) + Cl₂(g) ⇌ ICl₃(s) (forward reaction exothermic, dark brown to yellow), which changes would cause the mixture to become more brown? (select all that apply)

20.In the Contact process, sulfur dioxide reacts with oxygen: 2SO₂(g) + O₂(g) ⇌ 2SO₃(g). The forward reaction is exothermic. A chemist wants to increase the equilibrium yield of sulfur trioxide. Which single change would increase the yield?

21.Hydrogen reacts with iodine: H₂(g) + I₂(g) ⇌ 2HI(g). Iodine gas is purple and hydrogen iodide gas is colourless. The forward reaction is exothermic. The pressure of the sealed container is increased. What colour change, if any, is seen?

22.A reversible reaction reaches equilibrium in a closed container. The forward reaction is endothermic. The temperature is then decreased. Which statement describes what happens?

23.A reversible reaction is at equilibrium in a closed vessel. The concentration of one of the reactants is suddenly increased. According to Le Chatelier's principle, what happens to the position of equilibrium?

24.A sealed container holds an equilibrium mixture of N₂O₄ and NO₂: 2NO₂(g) ⇌ N₂O₄(g), where NO₂ is dark brown and N₂O₄ is colourless. The mixture is compressed, reducing the volume and increasing the pressure. What is observed?

25.For a reversible reaction at equilibrium, if the forward reaction is exothermic then the reverse reaction is endothermic, and the same amount of energy is transferred in each direction.

26.Adding an iron catalyst to the Haber process increases the equilibrium yield of ammonia.

27.Match each change to the effect it has on the equilibrium N₂(g) + 3H₂(g) ⇌ 2NH₃(g) (forward reaction exothermic).

28.Place the steps in order to show how a dynamic equilibrium is established when nitrogen and hydrogen are mixed in a closed container, starting with only N₂ and H₂ present.

29.For the equilibrium 2SO₂(g) + O₂(g) ⇌ 2SO₃(g) (forward reaction exothermic), which changes would increase the equilibrium yield of SO₃? (select all that apply)

30.A reversible reaction A(g) + B(g) ⇌ C(g) is at equilibrium in a closed container. The forward reaction is endothermic. Which statements are correct? (select all that apply)

31.What does the graph show about the effect of increasing temperature on the yield of ammonia at constant pressure?

32.What does the graph show about the effect of increasing pressure on the yield of ammonia at constant temperature?

33.A student heats a small sample of blue hydrated copper(II) sulfate crystals in a dry test tube held in a clamp, using a gentle Bunsen flame. A clear, colourless liquid condenses near the top of the tube and the solid turns white. The student then allows the tube to cool and adds a few drops of water to the white solid. Which observation and explanation is correct?

34.A sealed gas syringe contains an equilibrium mixture of nitrogen dioxide and dinitrogen tetroxide: 2NO₂(g) ⇌ N₂O₄(g). NO₂ is dark brown and N₂O₄ is colourless. The plunger is pushed in so that the volume of the gas mixture is halved at constant temperature. Which statements about the new equilibrium are correct? (select all that apply)

35.Match each change made to a system at equilibrium with its effect on the position of equilibrium.

36.The Contact process produces sulfur trioxide: 2SO₂(g) + O₂(g) ⇌ 2SO₃(g). The forward reaction is exothermic. A manufacturer currently uses 450 °C and 200 kPa with a vanadium(V) oxide catalyst. Which change would increase the equilibrium yield of SO₃ without changing the rate at which equilibrium is reached?

37.At equilibrium, the concentrations of the reactants and products are always equal.

38.A student sets up a sealed container with nitrogen and hydrogen and allows the Haber process equilibrium to be reached. The student then adds more nitrogen to the container and waits for equilibrium to be re-established. Which statement describes what happens?

39.A reversible reaction A(g) + B(g) ⇌ C(g) + D(g) is at equilibrium in a closed container. The forward reaction is exothermic. Which statements are correct? (select all that apply)

40.Place the steps of the Haber process in the correct order, starting with the raw materials.

41.Complete the sentence about dynamic equilibrium.

42.A reaction is carried out at a pressure of 2 atmospheres. Given that 1 atmosphere = 101 325 Pa, calculate the pressure in Pascals.

43.Give the name of the type of reaction in which the products can react to reform the original reactants.

44.Name the white powder that forms at the top of the test tube when ammonium chloride is heated.

45.What is the name of the process used to manufacture ammonia from nitrogen and hydrogen?

46.In the Haber process, the pressure used is about 200 atmospheres. Given that 1 atmosphere = 101 325 Pa, calculate this pressure in Pascals. Give your answer in standard form.

47.Complete the sentences about dynamic equilibrium using the words: equal, constant, closed.

48.Complete the sentence about the effect of concentration on equilibrium.

49.In the Contact process, sulfur dioxide is converted to sulfur trioxide: 2SO₂(g) + O₂(g) ⇌ 2SO₃(g). If the pressure is increased, the equilibrium shifts to the right. How many gas molecules are on the left-hand side of the equation?

50.A reversible reaction is carried out at a pressure of 200 atmospheres. Given that 1 atmosphere = 101 325 Pa, calculate the pressure in kilopascals (kPa). Give your answer to 3 significant figures.

51.For the equilibrium N₂(g) + 3H₂(g) ⇌ 2NH₃(g), the forward reaction is exothermic. At a certain temperature the equilibrium mixture contains 1.5 mol of N₂, 2.0 mol of H₂ and 3.0 mol of NH₃ in a 2.0 dm³ container. Calculate the concentration of ammonia in mol/dm³.

52.Complete the sentences about the effect of increasing pressure on the equilibrium N₂(g) + 3H₂(g) ⇌ 2NH₃(g).

53.Explain what is meant by dynamic equilibrium.

54.Explain why a catalyst does not change the yield of ammonia in the Haber process.

55.Explain, in terms of Le Chatelier's principle, why increasing the pressure increases the yield of ammonia in the Haber process: N₂(g) + 3H₂(g) ⇌ 2NH₃(g).

56.A reversible reaction is at equilibrium in a closed container. The forward reaction is exothermic. Explain the effect of increasing the temperature on the position of equilibrium and on the yield of products.

57.Explain why a catalyst increases the rate of a reversible reaction but does not change the position of equilibrium.

58.A reaction is carried out at a pressure of 2 atmospheres. Given that 1 atmosphere = 101 325 Pa, calculate the pressure in Pascals.

59.In the Haber process, the pressure used is about 200 atmospheres. Given that 1 atmosphere = 101 325 Pa, calculate this pressure in Pascals. Give your answer in standard form.

60.In the Contact process, sulfur dioxide is converted to sulfur trioxide: 2SO₂(g) + O₂(g) ⇌ 2SO₃(g). If the pressure is increased, the equilibrium shifts to the right. How many gas molecules are on the left-hand side of the equation?

61.A reversible reaction is carried out at a pressure of 200 atmospheres. Given that 1 atmosphere = 101 325 Pa, calculate the pressure in kilopascals (kPa). Give your answer to 3 significant figures.

62.For the equilibrium N₂(g) + 3H₂(g) ⇌ 2NH₃(g), the forward reaction is exothermic. At a certain temperature the equilibrium mixture contains 1.5 mol of N₂, 2.0 mol of H₂ and 3.0 mol of NH₃ in a 2.0 dm³ container. Calculate the concentration of ammonia in mol/dm³.