23. Rate of = physical changes reaction time average rate of reaction rate of reaction at a given time Average rate = total changes of reaction total time taken Rate of reaction at a given time = gradient of the curve at that instant = y 2 – y 1 / X 2 – X 1
24. Total changes Total time taken Average rate = total changes of reaction total time taken Volume of hydrogen gas ( cm 3 ) Time ( s )
31. Here’s the result : Time / s Reading of burette / cm 3 Volume of gas / cm 3
32. Then we plot the graph: Volume of hydrogen gas ( cm 3 ) Time ( s ) 5 10 0 35 30 25 20 15 60 30 90 180 210 240 270 300 150 120
33.
34. Average rate of reaction = total changes / total time taken Average rate of reaction = 34 cm 3 300 s = 0.113 cm 3 s -1 ** you’ll get the same answer by using graph
35.
36. b) Calculate the average rate of reaction in the first 90 seconds . Solution: this is accumulated !! Time / s Reading of burette / cm 3 Volume of gas / cm 3
37. Average rate of reaction = total changes / total time taken Average rate of reaction = 20 cm 3 90 s = 0.222 cm 3 s -1 ** you’ll get the same answer by using graph
38.
39.
40. Solution (a) : 22.00 – 10.50 = 11.50 cm 3 90-30 = 60 s Rate of reaction at 60 second = y 2 – y 1 x 2 - x 1 = 22.00 -10.50 90 -30 = 11.50 cm 3 60 s = 0.192 cm 3 s -1 ** 5 10 35 30 25 20 15 Time ( s ) 90 Volume of hydrogen gas ( cm 3 ) 0 60 30 180 210 240 270 300 150 120
41. Solution (b) : 35.50 – 30.00 = 5.50 cm 3 255-160 = 95 s Rate of reaction at 210 second = 35.50 -30.00 255 -160 = 5.50 cm 3 95 s = 0.058 cm 3 s -1 ** 5 10 35 30 25 20 15 Time ( s ) 90 Volume of hydrogen gas ( cm 3 ) 0 60 30 180 210 240 270 300 150 120
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47. Conclusion Rate of reaction very high Rate of reaction lower Curve becomes horizontal line No more reaction occur Rate of reaction = 0 cm 3 s -1 Rate of reaction More lower Total volume of gas Liberated (cm 3 ) Time (s / min)
51. Some reactions are fast & some reactions are very slow So do the chemical reactions in laboratory
52. What are the factors affect the rate of reaction ??
53. 2. T emperature 1. T otal surface area 4. C atalyst 5. P ressure 3. C oncentration 2T 2C 1P
54. How does the factors of Total surface area, Temperature, Concentration, Catalyst & Pressure affect the reaction rate?? 2T 2C 1P
55. Let’s do the experiment to investigate that: 1.Surface area smaller , rate of reaction 2.Concentration higher, rate of reaction 3.Temperature higher, rate of reaction 4.Catalyst added, rate of reaction
67. 1. the curves of graph for Magnesium mass against the time Magnesium Excess >>>
68. 2. the curves of graph for hydrochloric acid concentration against the time Hydrochloric acid Limited reactant
69. 3. the curves of graph for magnesium chloride concentration against the time Hydrochloric acid has been used up & reaction stopped
70. 4. the curves of graph for hydrogen gas volume against the time Hydrochloric acid has been used up & reaction stopped
71.
72. Hydrogen Gas / cm 3 Time / s Set 2 Set 1 The number of moles of chemical subtances are same Factor : total of surface area / Particle size
73.
74. Hydrogen Gas / cm 3 Time / s Set 4 Set 3 The number of moles of chemical subtances are same Factor : Concentration
75.
76. Hydrogen Gas / cm 3 Time / s Set 6 Set 5 The number of moles of chemical subtances are same Factor : Concentration
77.
78. Hydrogen Gas / cm 3 Time / s Set 8 Set 7 The number of moles of chemical subtances in Set 8 is higher, so the volume of gas realeased is higher Factor : Concentration
87. therefore some main ways of increasing the rate of a reaction: 1) increase the number of collisions 2) increase the amount of kinetic energy so that more collisions lead to a reaction 3) decrease the energy activation so that more reactants could be reacted what factors could cause 1, 2, 3?
