A manufacturer checks two batches labelled benzoic acid. The accepted melting point of pure benzoic acid is 122 ∘C122\ ^\circ\text{C}122 ∘C.
| Batch | Melting result in ∘C^\circ\text{C}∘C |
|---|---|
| A | 122 |
| B | 118 to 121 |
Give the meaning of a pure substance in chemistry.
Use the table.
Give the letter of the batch whose melting result supports the conclusion that it is pure benzoic acid.
Give two reasons why the melting result for batch B suggests that it is impure.
113 exam-style questions on AQA GCSE Chemistry 8.1 Purity, formulations and chromatography, covering 8.1.1 Pure substances, 8.1.2 Formulations, and 8.1.3 Chromatography. Each one has a worked solution and a mark scheme showing where the marks go.