A gas chromatography instrument is used to analyse a sample and reference substances under the same conditions. The table shows their retention times.
| Substance | Retention time (min) |
|---|---|
| Ethanol | 1.8 |
| Propan-1-ol | 3.2 |
| Butan-1-ol | 4.7 |
| Sample peaks | 1.8, 3.2, 4.1, 4.7 |
Identify the substances in the sample and explain what the peak at 4.1 minutes shows.
107 exam-style questions on OCR GCSE Chemistry 4.2 Identifying the products of chemical reactions, covering 4.2.1 Tests to identify gases, 4.2.2 Tests for aqueous ions and flame tests, and 4.2.3 Instrumental methods of analysis. Each one has a worked solution and a mark scheme showing where the marks go.