| Date | May 2013 | Marks available | 1 | Reference code | 13M.1.hl.TZ1.21 |
| Level | HL | Paper | 1 | Time zone | TZ1 |
| Command term | Identify | Question number | 21 | Adapted from | N/A |
Question
Which graph best represents a second-order reaction?
Markscheme
B
Examiners report
One respondent stated that graphs A and B look too similar so students might not be able to clearly see that the answer is B. The initial gradient of curve B is clearly greater so candidates should have recognized the faster decrease in initial concentration for a second order reaction. Curve A clearly shows a constant half-life so candidates should have recognized that it refers to a first order reaction. 60.65% of the candidates chose the correct answer B.
Syllabus sections
Additional higher level (AHL) » Topic 16: Chemical kinetics » 16.1 Rate expression and reaction mechanism
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