Purity and Formulations

Introduction to Chemical Analysis

• Chemical Analysis: Also known as analytical chemistry; involves instruments and methods for separating, identifying, and quantifying substances.

• Upcoming topics:

  • Paper chromatography for pigments separation

  • Filtration and crystallization for solids isolation

  • Distillation for liquid separation

  • Chemical tests for common gases

Key Terminology

• Pure Substance: Contains one type of compound or element; not mixed with anything else. Examples:

  • Pure water (only water molecules)

  • Pure sodium chloride

• Impurity: When substances mix, e.g., saltwater is a mixture of two compounds and isn't pure.

Importance of Purity

• Melting and Boiling Points: Only pure substances have specific melting/boiling points (e.g., water boils at 100°C, sodium chloride melts at 801°C).

• Physical Tests: Identifying substances using physical properties.

• Chemical Tests: Using reactions to identify substances.

• Impurities: Affects melting/boiling points; impure substances have these properties over a range of temperatures.

  • Example: Saltwater melting point ~ -2°C (lower) and boiling point ~ 100.5°C (higher).

Formulations

• Definition: Mixtures prepared with specific ratios of components for particular functions; akin to a recipe.

• Usage Examples: Fuels, cleaning agents, paints, medicines, alloys, fertilizers, food, and drink.

• Components Role: Each contributes different properties; e.g., in green paint, components ensure color and adhesion.

• Consistency in Proportions: Formulations must maintain the same proportions of components for reproducibility.

Conclusion

• Summary of key points on chemical analysis and the importance of purity and formulations.