GCSE Chemistry - The Reactivity Series - Metal Reactions | Displacement Reactions (2027/28 exams) — Transcript

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1. 0:06In today's video, we're going to take a
2. 0:08look at the reactivity series of metals
3. 0:11and see how metals react with both acids
4. 0:13and water.
5. 0:15Then to finish, we'll take a quick look
6. 0:17at how we use the reactivity series to
7. 0:19figure out what will happen in
8. 0:20displacement reactions.
9. 0:25If you remember the electron arrangement
10. 0:27of metals, what they all have in common
11. 0:29is that they have electrons in their
12. 0:31outermost shell that they want to get
13. 0:33rid of. And so when they react with
14. 0:36other substances, they get rid of these
15. 0:38outer shell electrons and form positive
16. 0:41ions.
17. 0:43So when we talk about the reactivity of
18. 0:45a metal, all we mean is how easily it
19. 0:48forms these positive ions.
20. 0:50The metals that form ions most easily
21. 0:52are the most reactive. And by comparing
22. 0:55all of the metals, we can arrange them
23. 0:57in order of their reactivity like this,
24. 0:59which we call the reactivity series.
25. 1:03Now, even though carbon and hydrogen
26. 1:05aren't metals, we often still include
27. 1:07them in reactivity series as references
28. 1:10to compare the metals against.
29. 1:13The most reactive metals are the group
30. 1:15one metals with the group two metals
31. 1:18being a bit less reactive and the
32. 1:20transition metals generally the least
33. 1:22reactive.
34. 1:24To figure out this list in the first
35. 1:25place though, we need to react each of
36. 1:27the metals with either acid or water and
37. 1:30compare their relative reactivity by
38. 1:33seeing how fast or violent the reactions
39. 1:35are.
40. 1:39If we react a metal with an acid, it
41. 1:42will form a salt and hydrogen gas.
42. 1:45For example, if we reacted potassium
43. 1:47with hydrochloric acid, it would form
44. 1:50potassium chloride and hydrogen.
45. 1:53And because potassium is so reactive, it
46. 1:55would react explosively, possibly
47. 1:58catching fire and whizzing around as it
48. 2:00produces loads of hydrogen.
49. 2:03The reactions would then get gradually
50. 2:05less violent as we go down the series.
51. 2:08And by the time we get to magnesium, it
52. 2:10would just produce lots of bubbles as
53. 2:12the solid metal disappears in the acid.
54. 2:16We'd then see fewer bubbles with zinc
55. 2:18and iron. And copper usually won't react
56. 2:21at all.
57. 2:24Rather than just watching the reactions
58. 2:26to see how violent they are, we can also
59. 2:28measure the temperature change of the
60. 2:29reactions. because the most reactive
61. 2:32metals will produce the most heat.
62. 2:35If we're going to compare the metals
63. 2:37though, we need to make sure it's a fair
64. 2:38test by ensuring that each of the metal
65. 2:41samples that we use has the same mass
66. 2:43and same surface area and that we use
67. 2:46the same type and concentration of acid
68. 2:48each time.
69. 2:52Now if we instead react metals with
70. 2:55water rather than acids, they form metal
71. 2:58hydroxides and hydrogen. For example,
72. 3:01lithium plus water would go to form
73. 3:03lithium hydroxide and hydrogen.
74. 3:07However, only the most reactive metals
75. 3:09are reactive enough to do this. Zinc,
76. 3:12iron, and copper won't react at all,
77. 3:15while magnesium will only react very
78. 3:17slightly.
79. 3:21Now the last thing we need to cover is
80. 3:23displacement reactions.
81. 3:25The idea here is that more reactive
82. 3:27metals can displace less reactive ones.
83. 3:31So if we put some magnesium into a
84. 3:33solution of iron sulfate, then the
85. 3:35magnesium would displace the iron to
86. 3:38form magnesium sulfate plus iron because
87. 3:41the magnesium is more reactive than the
88. 3:43iron.
89. 3:45Whereas if we added copper to a solution
90. 3:47of iron sulfate, then nothing would
91. 3:49happen because copper is less reactive
92. 3:51than iron, so can't displace it.
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