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1.4 rate of reaction(1.2d)...biology
1.4 rate of reaction(1.2d)...biology
1.4 rate of reaction(1.2d)...biology
1.4 rate of reaction(1.2d)...biology
1.4 rate of reaction(1.2d)...biology
1.4 rate of reaction(1.2d)...biology
1.4 rate of reaction(1.2d)...biology
1.4 rate of reaction(1.2d)...biology
1.4 rate of reaction(1.2d)...biology
1.4 rate of reaction(1.2d)...biology
1.4 rate of reaction(1.2d)...biology
1.4 rate of reaction(1.2d)...biology
1.4 rate of reaction(1.2d)...biology
1.4 rate of reaction(1.2d)...biology
1.4 rate of reaction(1.2d)...biology
1.4 rate of reaction(1.2d)...biology
1.4 rate of reaction(1.2d)...biology
1.4 rate of reaction(1.2d)...biology
1.4 rate of reaction(1.2d)...biology
1.4 rate of reaction(1.2d)...biology
1.4 rate of reaction(1.2d)...biology
1.4 rate of reaction(1.2d)...biology
1.4 rate of reaction(1.2d)...biology
1.4 rate of reaction(1.2d)...biology
1.4 rate of reaction(1.2d)...biology
1.4 rate of reaction(1.2d)...biology
1.4 rate of reaction(1.2d)...biology
1.4 rate of reaction(1.2d)...biology
1.4 rate of reaction(1.2d)...biology
1.4 rate of reaction(1.2d)...biology
1.4 rate of reaction(1.2d)...biology
1.4 rate of reaction(1.2d)...biology
1.4 rate of reaction(1.2d)...biology
1.4 rate of reaction(1.2d)...biology
1.4 rate of reaction(1.2d)...biology
1.4 rate of reaction(1.2d)...biology
1.4 rate of reaction(1.2d)...biology
1.4 rate of reaction(1.2d)...biology
1.4 rate of reaction(1.2d)...biology
1.4 rate of reaction(1.2d)...biology
1.4 rate of reaction(1.2d)...biology
1.4 rate of reaction(1.2d)...biology
1.4 rate of reaction(1.2d)...biology
1.4 rate of reaction(1.2d)...biology
1.4 rate of reaction(1.2d)...biology
1.4 rate of reaction(1.2d)...biology
1.4 rate of reaction(1.2d)...biology
1.4 rate of reaction(1.2d)...biology
1.4 rate of reaction(1.2d)...biology
1.4 rate of reaction(1.2d)...biology
1.4 rate of reaction(1.2d)...biology
1.4 rate of reaction(1.2d)...biology
1.4 rate of reaction(1.2d)...biology
1.4 rate of reaction(1.2d)...biology
1.4 rate of reaction(1.2d)...biology
1.4 rate of reaction(1.2d)...biology
1.4 rate of reaction(1.2d)...biology
1.4 rate of reaction(1.2d)...biology
1.4 rate of reaction(1.2d)...biology
1.4 rate of reaction(1.2d)...biology
1.4 rate of reaction(1.2d)...biology
1.4 rate of reaction(1.2d)...biology
1.4 rate of reaction(1.2d)...biology
1.4 rate of reaction(1.2d)...biology
1.4 rate of reaction(1.2d)...biology
1.4 rate of reaction(1.2d)...biology
1.4 rate of reaction(1.2d)...biology
1.4 rate of reaction(1.2d)...biology
1.4 rate of reaction(1.2d)...biology
1.4 rate of reaction(1.2d)...biology
1.4 rate of reaction(1.2d)...biology
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1.4 rate of reaction(1.2d)...biology

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this is an experiment …

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  • 1. Effect of Catalyst on the rate of reaction
    • Experiment 1.4: To study the effect of a catalyst on the rate of decomposition of hydrogen peroxide
  • 2. Effect of Catalyst on the rate of reaction
    • Problem statement
    • How do catalyst affect the rate of decomposition of hydrogen peroxide
  • 3. Effect of Catalyst on the rate of reaction
    • Hypothesis
    • Manganese (IV) oxide speed up the decomposition of hydrogen peroxide
  • 4. Effect of Catalyst on the rate of reaction
    • Variables:
    • (a) Manipulated variable: The presence of manganese (IV) oxide
    • (b) Responding variable: The release of oxygen gas
    • (c) Fixed (controlled) variables: Volume and concentration of hydrogen peroxide
  • 5. Effect of Catalyst on the rate of reaction
    • Apparatus
    • Boiling tube and wooden splinter
    • Material
    • Hydrogen peroxide and manganese (IV) oxide
  • 6. Effect of Catalyst on the rate of reaction
    • Procedure
    • 1 A boiling tube is half-filled with hydrogen peroxide.
    • 2 A glowing splinter is placed at the mouth of the boiling tube to test for the gas evolved (Figure 1.25).
  • 7. Effect of Catalyst on the rate of reaction
    • Procedure
    • 3 The changes that take place inside the boiling tube and on the glowing splinter are recorded.
    • 4 0.5 g of manganese (IV) oxide, MnO 2 is added to hydrogen peroxide and shaken. The changes that take place in the boiling tube and on the glowing splinter are recorded.
  • 8. Effect of Catalyst on the rate of reaction
    • Results
  • 9. Effect of Catalyst on the rate of reaction
    • Discussion
    • 1 Hydrogen peroxide decomposes to oxygen gas and water according to the equation:
    • 2H 2 O 2 (aq)  2H 2 O(l) + O 2 (g)
  • 10. Effect of Catalyst on the rate of reaction
    • Discussion
    • 2 The glowing splinter is rekindled in the presence of oxygen gas.
  • 11. Effect of Catalyst on the rate of reaction
    • Conclusion
    • The rate of evolution of oxygen gas increases when manganese (IV) oxide is added to
    • hydrogen peroxide. This proves that manganese (IV) oxide acts as a catalyst and speeds up the decomposition of hydrogen peroxide to water and oxygen. The hypothesis is accepted.
  • 12. The effect of concentration of hydrogen peroxide on the rate of reaction
    • 1 The graph in Figure 1.21 shows the effect of concentration of hydrogen peroxide on the rate of decomposition of hydrogen peroxide.
  • 13. The effect of concentration of hydrogen peroxide on the rate of reaction
    • In Experiment I, 50 cm 3 of 0.14 mol dm -3 of hydrogen peroxide and 0.2 g of manganese (IV) oxide are used.
    • In Experiment II, a solution containing 25 cm 3 of the same hydrogen peroxide mixed with 25 cm 3 of water and 0.2 g of manganese (IV) oxide are used. For both the experiments, the temperature is kept constant.
  • 14. The effect of concentration of hydrogen peroxide on the rate of reaction
    • 2 (a) For Experiment I
    • Concentration of H 2 O 2 = 0.14 mol dm -3
    • For experiment II, hydrogen peroxide is diluted.
    • (M 1 V 1 )before dilution =(M 2 V 2 )after dilution
    • Concentration of H 2 O 2 after dilution
  • 15. The effect of concentration of hydrogen peroxide on the rate of reaction
    • 2 (b) At any particular instant, the gradient of graph I is greater than the gradient of graph II. This means that the rate of reaction in Experiment I is faster than the rate of reaction in experiment II. We can therefore conclude that the higher the concentration of hydrogen peroxide, the faster the rate of reaction.
  • 16. Factors that affect the rate of reaction
    • 2 (c) The maximum volume of oxygen gas produced in Experiment I is twice that produced in Experiment II. This is because the number of moles of hydrogen peroxide used in Experiment I is twice that used in Experiment II.
  • 17. Explaining the effectiveness of different catalysts on the rate of decomposition of hydrogen peroxide
    • 1 Figure 1.22 shows the results of an experiment carried out to study the effect of different catalysts (of the same mass) on the rate of decomposition of hydrogen peroxide.
  • 18. Explaining the effectiveness of different catalysts on the rate of decomposition of hydrogen peroxide
    • In Experiment I, 50 cm 3 of hydrogen peroxide and 0.5 g of manganese(IV) oxide are used.
    • In Experiment II, 50 cm 3 of hydrogen peroxide and 0.5 g of iron (III) oxide are used.
    • For both the experiments, the concentration and volume of hydrogen peroxide as well as the temperature are kept constant .
  • 19. Explaining the effectiveness of different catalysts on the rate of decomposition of hydrogen peroxide
    • 2 Analysis of the reaction rate curve in Figure 1.22
    • (a) At any particular instant, the gradient of graph I is greater than the gradient of graph II . This means that the rate of reaction in Experiment I is faster than the rate of reaction in Experiment II. Thus, the experiment proves that manganese(IV) oxide is a more effective catalyst than iron(III) oxide in the decomposition of hydrogen peroxide.
  • 20. Explaining the effectiveness of different catalysts on the rate of decomposition of hydrogen peroxide
    • 2 Analysis of the reaction rate curve in Figure 1.22
    • (b) The maximum volumes of oxygen gas collected in both the experiments are the same because the volume and concentration of hydrogen peroxide used are the same. This experiment shows that a catalyst does not change the yield of the products.
  • 21. Amount of catalysts on the rate of decomposition of hydrogen peroxide
    • Experiment 1.5: To Invstigate the effect of the amount of the catalyst, manganese (IV) oxide on the decomposition of hydrogen peroxide
  • 22. Amount of catalysts on the rate of decomposition of hydrogen peroxide
    • Problem statement
    • How does the amount of manganese(IV)oxide affect on the decomposition of hydrogen peroxide?
  • 23. Amount of catalysts on the rate of decomposition of hydrogen peroxide
    • Hypothesis
    • The rate of the decomposition of hydrogen peroxide increases when the amount of the catalyst used is increased
  • 24. Amount of catalysts on the rate of decomposition of hydrogen peroxide
    • Variables
    • (a) Manipulated variable: Amount of the catalyst used
    • (b) Responding variable: The volume of oxygen given off at half-minute intervals
    • (c) Fixed (controlled) variables: Volume and concentration of hydrogen peroxide, temperature of the experiment and type of the catalyst
  • 25. Amount of catalysts on the rate of decomposition of hydrogen peroxide
    • Apparatus
    • Measuring cylinder, conical flask, delivery tube, rubber stopper, retort stand clamp and burette.
    • Materials
    • 0.2 mol dm -3 hydrogen peroxide and manganese(IV) oxide.
  • 26. Amount of catalysts on the rate of decomposition of hydrogen peroxide
    • Experiment 1.5: To Invstigate the effect of the amount of the catalyst, manganese (IV) oxide on the decomposition of hydrogen peroxide
  • 27. Amount of catalysts on the rate of decomposition of hydrogen peroxide
    • Procedure
    • 1 Using a measuring cylinder, 25 cm 3 of 0.2 mol dm -3 hydrogen peroxide is measured into a conical flask and 0.5 g of manganese(IV) oxide is added to the hydrogen peroxide.
  • 28. Amount of catalysts on the rate of decomposition of hydrogen peroxide
    • Procedure
    • 2 The conical flask is immediately closed with a stopper fitted with a delivery tube (Figure 1.28) and the stopwatch is started simultaneously. The conical flask is swirled gently.
  • 29. Amount of catalysts on the rate of decomposition of hydrogen peroxide
    • Procedure
    • 3 The total volume of oxygen gas given off is determined from the burette reading at intervals of ½ minute for 4 minutes.
  • 30. Amount of catalysts on the rate of decomposition of hydrogen peroxide
    • Procedure
    • 4 The experiment is repeated using 0.20 g of manganese(IV) oxide instead of 0.50 g of manganese(IV) oxide.
  • 31. Amount of catalysts on the rate of decomposition of hydrogen peroxide
    • Results
    • Experiment l.
    • Decomposition of hydrogen peroxide in the presence of 0.5 g of manganese(IV) oxide
  • 32. Amount of catalysts on the rate of decomposition of hydrogen peroxide
    • Results
    • Experiment l.
    • Decomposition of hydrogen peroxide in the presence of 0.2 g of manganese(IV) oxide
  • 33. Amount of catalysts on the rate of decomposition of hydrogen peroxide
    • Discussion
    • 1 Based on the results of Experiments I and II, two graphs of total volume of oxygen gas against time for the decomposition of hydrogen peroxide are plotted on the same axes (Figure 1.29).
  • 34. Amount of catalysts on the rate of decomposition of hydrogen peroxide
    • Discussion
    • 1 Graph I refers to the decomposition of hydrogen peroxide catalysed by 0.5 g of manganese(IV) oxide, while graph II refers to the decomposition of hydrogen peroxide catalysed by 0.2 g of manganese(IV) oxide.
  • 35. Amount of catalysts on the rate of decomposition of hydrogen peroxide
    • Discussion
    • 2 The gradient of graph I is steeper than the gradient of graph II, This shows that the rate of reaction I is faster than the rate of reaction II.
  • 36. Amount of catalysts on the rate of decomposition of hydrogen peroxide
    • Discussion
    • 3 If the decomposition of hydrogen peroxide in both the experiments is allowed to complete, the maximum volumes of oxygen gas collected for both the experiments will be the same .
  • 37. Amount of catalysts on the rate of decomposition of hydrogen peroxide
    • Discussion
  • 38. Amount of catalysts on the rate of decomposition of hydrogen peroxide
    • Discussion
    • 4 The quantity of catalyst does not affect the amount of products formed.
  • 39. Amount of catalysts on the rate of decomposition of hydrogen peroxide
    • Conclusion
    • The larger the amount of the catalyst manganese(IV) oxide used, the higher the rate of decomposition of hydrogen peroxide.
  • 40. Applications of factors that affect rates of reaction in daily life and in industrial processes
    • Combustion of charcoal
    • 1 Large pieces of charcoal will not catch fire easily because the total surface area exposed to oxygen is small.
  • 41. Applications of factors that affect rates of reaction in daily life and in industrial processes
    • Combustion of charcoal
    • 2 If small pieces of charcoal are used, they can burn easily. This is because the total surface area exposed to the air increases. Thus, the rate of reaction with oxygen (combustion) increases.
  • 42. Applications of factors that affect rates of reaction in daily life and in industrial processes
    • Storing food in refrigerators
    • 1 The decomposition and decay of food is a chemical reaction caused by the action of microorganisms such as bacteria and fungi. These microorganisms multiply very rapidly at the temperature range of 10-60 °C.
  • 43. Applications of factors that affect rates of reaction in daily life and in industrial processes
    • Storing food in refrigerators
    • 2 Room temperature is the optimum temperature for the breeding of microorganisms in food. As a result, food turns bad quickly at room temperature.
  • 44. Applications of factors that affect rates of reaction in daily life and in industrial processes
    • Storing food in refrigerators
    • 3 At low temperatures, for example, 5 °C (the normal temperature of a refrigerator), the activities of bacteria are slowed down . Hence, food that is kept in a refrigerator will last longer because the decaying reaction that destroys the food can be slowed down.
  • 45. Applications of factors that affect rates of reaction in daily life and in industrial processes
    • Storing food in refrigerators
    • 4 In the supermarkets, fish, meat and other types of fresh foods are kept in deep-freeze compartments where the temperature is about -20 °C. This keeps the food fresh for a few months because the very low temperature slows down the chemical reactions that cause the food to decay.
  • 46. Applications of factors that affect rates of reaction in daily life and in industrial processes
    • Cooking food in pressure cookers
    • 1 Pressure cookers are used to speed up cooking.
  • 47. Applications of factors that affect rates of reaction in daily life and in industrial processes
    • Cooking food in pressure cookers
    • 2 In the pressure cooker, the higher pressure enables water or oil to boil at a temperature higher than their normal boiling points. Furthermore, an increase in pressure causes an increase in the number of water molecules or cooking oil molecules coming into contact and colliding with the food particles.
  • 48. Applications of factors that affect rates of reaction in daily life and in industrial processes
    • Cooking food in pressure cookers
    • 3 At a higher temperature and pressure, the rate of reaction becomes faster. Thus, food cook faster in pressure cookers.
  • 49. Applications of factors that affect rates of reaction in daily life and in industrial processes
    • Uses of catalysts in industry
    • 1 From the economic point of view, catalysts play a vital role in industrial processes.
  • 50. Applications of factors that affect rates of reaction in daily life and in industrial processes
    • Uses of catalysts in industry
    • 2 Catalysts do not increase the yields of reactions . However, catalysts are used widely in industrial processes to speed up the rates of reactions so that the same amount of products can be obtained in a shorter time. As a result, the use of catalysts brings down the cost of production .
  • 51. Applications of factors that affect rates of reaction in daily life and in industrial processes
    • Uses of catalysts in industry
    • 3 In the chemical industry, small pellets of solid catalysts are used instead of big lumps. This is to give a larger surface for catalytic reaction to occur and hence a faster reaction will result.
  • 52. Applications of factors that affect rates of reaction in daily life and in industrial processes
    • The manufacture of ammonia (Haber process)
    • 1 The Haber process is an industrial process for the manufacture of ammonia from nitrogen and hydrogen.
  • 53. Applications of factors that affect rates of reaction in daily life and in industrial processes
    • The manufacture of ammonia (Haber process)
    • 2 Nitrogen and hydrogen do not react at room temperature and pressure. High temperature and pressure and the presence of a catalyst are required for nitrogen to react with hydrogen.
  • 54. Applications of factors that affect rates of reaction in daily life and in industrial processes
    • The manufacture of ammonia (Haber process)
    • 3 The optimum conditions for obtaining a maximum yield of ammonia in the Haber process are as follows:
    • (a) Temperature: 450-550 o C
    • (b) Pressure : 200-500 atmospheres
    • (c) Catalyst: Finely divided iron ( Fe )
  • 55. Applications of factors that affect rates of reaction in daily life and in industrial processes
    • The manufacture of ammonia (Haber process)
    • 4 In terms of industrial processes, a temperature of 450 °C is considered as moderately high but the rate of reaction is slow at this temperature. Thus, a catalyst is required to increase the rate of reaction.
  • 56. Applications of factors that affect rates of reaction in daily life and in industrial processes
    • 5 In the Haber process, ammonia is produced when a mixture of nitrogen and hydrogen (in the ratio of 1:3 by volume) is passed over finely divided iron as catalyst at 450-500 °C and 200-500 atmospheres. Under these conditions, about 10% yield of ammonia is obtained.
  • 57. Applications of factors that affect rates of reaction in daily life and in industrial processes
    • The manufacture of sulphuric add (Contact process)
    • 1 The contact process is the industrial process for the manufacture of sulphuric acid from sulphur and oxygen .
  • 58. Applications of factors that affect rates of reaction in daily life and in industrial processes
    • The manufacture of sulphuric add (Contact process)
    • Raw materials required: sulphur, air and water.
    • Conditions for the reaction of SO 2 with O 2 (from the air):
    • (a) Temperature: 450-500 °C
    • (b) Pressure: 1-2 atmospheres
    • (c) Catalyst: Vanadium(V) oxide, V 2 O 5
  • 59. Applications of factors that affect rates of reaction in daily life and in industrial processes
    • 2 The following reaction scheme shows the steps involved in the manufacture of sulphuric acid:
  • 60. Applications of factors that affect rates of reaction in daily life and in industrial processes
    • 3 In Step 2, sulphur dioxide is oxidised to sulphur trioxide. The mixture of sulphur dioxide and oxygen is passed over vanadium(V) oxide, V 2 O 5 , as catalyst at 450-500 °C and a pressure of 1-2 atmospheres to form sulphur trioxide. Under these conditions, a yield of 98% of sulphur trioxide is obtained.
  • 61. Applications of factors that affect rates of reaction in daily life and in industrial processes
    • The manufacture of nitric acid (Ostwald process)
    • 1. The Ostwald process is used to manufacture nitric acid .
    • Raw materials required: ammonia , air and water
    • Conditions:
    • (a) Temperature: 900 ° C
    • (b) Pressure: 1-8 atmospheres
    • (c) Catalyst: platinum
  • 62. Applications of factors that affect rates of reaction in daily life and in industrial processes
    • The manufacture of nitric acid (Ostwald process)
    • The following reaction scheme shows the steps involved in the manufacture of nitric acid.
  • 63. Applications of factors that affect rates of reaction in daily life and in industrial processes
    • The manufacture of nitric acid (Ostwald process)
    • 2 In the Ostwald process, nitrogen monoxide, NO , is produced (step 1) when ammonia gas is passed over the platinum (Pt) catalyst at about 900 ° C and 1-8 atmospheres.
    • In this reaction, ammonia is oxidised to nitrogen monoxide.
  • 64. Applications of factors that affect rates of reaction in daily life and in industrial processes
    • Example 5
    • Two experiments were carried out to determine the rate of producing oxygen gas during the decomposition of hydrogen peroxide. In Experiment I, 20 cm 3 of 2 moldm -3 hydrogen peroxide were used and the results of the experiment are shown on graph I in Figure 1.26.
  • 65. Applications of factors that affect rates of reaction in daily life and in industrial processes
    • Example 5
    • (a) Sketch a graph on the same axes to show the results of the experiments that will be obtained if 5 cm 3 of 4 mol dm -3 hydrogen peroxide were used for the reaction.
  • 66. Applications of factors that affect rates of reaction in daily life and in industrial processes
    • Example 5
    • Solution
    • (a)
  • 67. Applications of factors that affect rates of reaction in daily life and in industrial processes
    • Example 5
    • (b) Explain your answer in (a).
  • 68. Applications of factors that affect rates of reaction in daily life and in industrial processes
    • Example 5
    • Solution
    • (b) Differences in terms of rate of reaction
    • Graph II is steeper than graph I because the rate of reaction in Experiment II is expected to be faster than Experiment I. When the concentration of hydrogen peroxide is increased from 2 moldm -3 to 4 mol dm -3 , the rate of reaction also increases
  • 69. Applications of factors that affect rates of reaction in daily life and in industrial processes
    • Example 5
    • Solution
    • (b) Number of moles of H 2 O 2 used in Experiment I
  • 70. Applications of factors that affect rates of reaction in daily life and in industrial processes
    • Experiment 6
    • Solution
    • (b) Number of moles of H 2 O 2 used in Experiment I
    •  Volume of oxygen collected at room temperature in Experiment I
    2H 2 O 2 (aq)  2H 2 O(l) + O 2 (g) 2mol 1mol
  • 71. Applications of factors that affect rates of reaction in daily life and in industrial processes
    • Experiment 6
    • Solution
    • (b) Number of moles of H 2 O 2 used in
    • Experiment II=
  • 72. Applications of factors that affect rates of reaction in daily life and in industrial processes
    • Example 5
    • Solution
    • (b) Volume of oxygen collected at room temperature in Experiment II
    • =
  • 73. Applications of factors that affect rates of reaction in daily life and in industrial processes
    • Example 5
    • (c) State the controlled variables for both the experiments.
  • 74. Applications of factors that affect rates of reaction in daily life and in industrial processes
    • Example 5
    • Solution
    • (c) Fixed (controlled) variables:
    • In both the experiments, the same mass of the catalyst and the same temperature of reaction are used.

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