Question 19M.3.sl.TZ1.4c(i)
| Date | May 2019 | Marks available | [Maximum mark: 2] | Reference code | 19M.3.sl.TZ1.4c(i) |
| Level | sl | Paper | 3 | Time zone | TZ1 |
| Command term | Outline | Question number | c(i) | Adapted from | N/A |
Polybutadiene, used in truck tyres, is a polymer of buta-1,3-diene. The spatial arrangement of atoms in the polymer depends on the type of catalyst used.
Tyre fires emit trace quantities of polychlorinated dibenzofurans and polychlorinated dibenzo-p-dioxin.
Outline, using section 31 of the data booklet, why polychlorinated dibenzofuran is not classed chemically as a dioxin but considered “dioxin-like”.
[2]
does not contain heterocyclic ring with 2 oxygen atoms
OR
middle ring has only 1 oxygen atom [✔]
produces similar toxic effects to dioxins [✔]
Note: Accept “does not contain dioxin ring” for M1.
This was a question that highlighted a perennial problem; students appearing to know the answer but not having sufficient command of the English language to express it accurately. A number did identify similar toxic effects as the reason for being “dioxin like”.
