Chemical AnalysisTopic Summary
Topic Summary: Purity and Formulations
Part of Purity & Formulations — GCSE Chemistry
This topic summary covers Topic Summary: Purity and Formulations within Purity & Formulations for GCSE Chemistry. Revise Purity & Formulations in Chemical Analysis for GCSE Chemistry with 20 exam-style questions and 12 flashcards. This topic appears regularly enough that it should still be part of a steady revision cycle. It is section 13 of 13 in this topic. Use this topic summary to connect the idea to the wider topic before moving on to questions and flashcards.
Topic position
Section 13 of 13
Practice
20 questions
Recall
12 flashcards
Topic Summary: Purity and Formulations
Key Definitions
- Pure substance: one type of element/compound only
- Formulation: designed mixture with measured component quantities
- Melting point depression: impurities lower melting point
- Boiling point elevation: impurities raise boiling point
Pure Substance Properties
- Sharp, fixed melting point
- Sharp, fixed boiling point
- Temperature constant during state change
- One spot on chromatogram
Effect of Impurities
- Lower the melting point
- Raise the boiling point
- Cause melting/boiling over a range
- Broader range = more impurities
Formulation Examples
- Paint: pigment + binder + solvent
- Medicines: active ingredient + binder + filler
- Petrol: hydrocarbons + octane improvers
- Alloys: e.g. steel = iron + carbon