An essential oil extract contains four active volatile compounds, W, X, Y, and Z, which are analyzed by gas chromatography and mass spectrometry. The results are summarized in the table below:
| Compound | Retention time / minutes | Relative peak area (relative molar proportion) | m/zm/zm/z of molecular ion peak |
|---|---|---|---|
| W | 1.8 | 2.4 | 136 |
| X | 2.9 | 4.5 | 150 |
| Y | 3.8 | 1.6 | 164 |
| Z | 4.5 | 5.8 | 164 |
The concentration of compound X in the essential oil extract is 1.35×10−1 g dm−31.35 \times 10^{-1}\text{ g dm}^{-3}1.35×10−1 g dm−3.
Using the results, calculate the concentration, in mol dm−3\text{mol dm}^{-3}mol dm−3, of the active compound Z in the extract.
Give your answer to two significant figures.
6 exam-style questions on OCR A A Level Chemistry Chromatography and qualitative analysis. Each one has a worked solution and a mark scheme showing where the marks go.