A technician has a waste mixture from a school laboratory.
The mixture contains sand, ethanol, water and dissolved sodium chloride.
The table shows information about the substances in the mixture.
| Substance | Melting point (°C) | Boiling point (°C) | Soluble in water? |
|---|---|---|---|
| sand | 1710 | 2230 | no |
| ethanol | −114 | 78 | yes |
| water | 0 | 100 | — |
| sodium chloride | 801 | 1413 | yes |
Ethanol is flammable.
Suggest how the technician should heat the mixture safely.
Describe how the technician could obtain pure samples of sand, ethanol and sodium chloride from the mixture.
Explain each step using the information in the table.
The technician collects some ethanol. It boils over a range of 78 °C to 84 °C.
What does this tell you about the ethanol?
51 exam-style questions on OCR GCSE Chemistry 2.1 Purity and separating mixtures, covering 2.1.1 Pure substances and melting point data, 2.1.2 Relative formula mass and empirical formula, 2.1.3 Formulations as useful mixtures, 2.1.4 Techniques for separating mixtures, and 2.1.5 Chromatography and Rf values. Each one has a worked solution and a mark scheme showing where the marks go.