Question 19N.3.sl.TZ0.12
| Date | November 2019 | Marks available | [Maximum mark: 4] | Reference code | 19N.3.sl.TZ0.12 |
| Level | sl | Paper | 3 | Time zone | TZ0 |
| Command term | Deduce, Suggest | Question number | 12 | Adapted from | N/A |
Octane number is a measure of the performance of engine fuel.
Suggest why a high-octane number fuel is preferable.
[1]
low knocking/auto-ignition
NOTE: Do not accept “pre-ignition”.
OR
more efficient fuel
NOTE: Accept “less CO2 emissions since knocking engine uses more fuel «to produce the same power»”.
OR
high compression
OR
more power extracted
OR
more air going into engine / turbocharging
OR
less engine damage ✔
Reforming reactions are used to increase the octane number of a hydrocarbon fuel.
Suggest the structural formulas of two possible products of the reforming reaction of heptane, C7H16.
[2]
Any two of:
NOTE: Accept skeletal formulas or full or condensed structural formulas.
Accept any other branched cycloalkane that contains 7 carbons.
Do not accept any alkenes.
Penalise missing hydrogens or bond connectivities once only in Option C.
Accept hydrogen as the second product if the first product is toluene or a cycloalkane.
The 1H NMR spectrum of one of the products has four signals. The integration trace shows a ratio of the areas under the signals of 9 : 3 : 2 : 2.
Deduce the structural formula of the product.
[1]
NOTE: Accept a skeletal formula or a full or condensed structural formula.
Penalise missing hydrogens or bond connectivities once only in Option C.
