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Rate of reaction by gas syringe
|
Time t / s |
Volume of CO2 Vt / cm3 |
Vfinal - Vt / cm3 |
|
0 |
0 |
95 |
|
10 |
10 |
85 |
|
20 |
20 |
75 |
|
31 |
30 |
65 |
|
43 |
40 |
55 |
|
58 |
50 |
45 |
|
74 |
60 |
35 |
|
97 |
70 |
25 |
|
137 |
80 |
15 |
|
¥ |
95 |
0 |
The graph shows two consecutive half-lives of 50s. A graph with a constant half-life shows a first order reaction. Bear in mind that real data is rarely perfect, so do not be surprised if, when you do your own experiment, the half-lives are slightly different. It is easy to distinguish a first order graph from a zero order one (this is a straight line), or from a second order graph which will have a clearly increasing half-life. For example two consecutive half-lives of 50 s and 54 s would be a first order graph whereas 50 s and 86 s would be a second order one.
