A manufacturer makes a solid cosmetic stick from wax, oil and pigment.
The required recipe and melting range are shown in the table.
| Wax (%) | Oil (%) | Pigment (%) | Required melting range (∘C^\circ\mathrm{C}∘C) |
|---|---|---|---|
| 55 | 40 | 5 | 50 to 55 |
The manufacturer tests three batches.
| Batch | Wax (%) | Oil (%) | Pigment (%) | Measured melting range (∘C^\circ\mathrm{C}∘C) |
|---|---|---|---|---|
| A | 55 | 40 | 5 | 50 to 55 |
| B | 50 | 45 | 5 | 46 to 53 |
| C | 58 | 37 | 5 | 52 to 58 |
A student claims that all three batches are poor quality because none of them has a single melting point.
Evaluate the student's claim. Use the information in the tables and your knowledge of formulations.
102 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.