This definitions covers Key Definitions 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 6 of 13 in this topic. Make sure you can use the exact wording confidently, because definition marks are often lost through vague language.
Topic position
Section 6 of 13
Practice
20 questions
Recall
12 flashcards
📖 Key Definitions
Pure substance (chemistry): A substance that contains only ONE type of element or compound. It has a sharp, fixed melting point and boiling point.
Formulation: A mixture that has been carefully designed so that each component is present in a measured quantity to give the product specific, desirable properties.
Melting point: The temperature at which a solid changes to a liquid at constant pressure. For a pure substance this is a fixed, sharp temperature.
Boiling point: The temperature at which a liquid changes to a gas at constant pressure.
Melting point depression: The lowering of a substance's melting point when impurities are present.