64. Purity & Formulations

Purity & Formulations

Based on the video, here are the notes on chemical purity, how to test for it, and the definition of formulations.

1. Chemical Purity

In chemistry, a pure substance is something that contains only one type of compound or element and is not mixed with anything else.

• Examples of Pure Substances: Pure water (only H2O molecules) or pure sodium chloride (NaCl).

• Impure Substances: Mixtures like salt water are considered impure because they contain more than one different compound.

2. Testing for Purity

Purity is determined by testing the physical properties of a substance, specifically its melting and boiling points.

• Pure Substances: Melt and boil at specific, fixed temperatures.

  • Example: Pure water boils at exactly 100°C.

  • Example: Pure sodium chloride (NaCl) melts at 801°C.

• Impure Substances: Do not have specific melting or boiling points. Instead, they melt and boil over a range of temperatures.

• Effect of Impurities: * They lower the melting point.

  • They increase the boiling point.

  • Example: Salt water boils at approximately 100.5°C and melts at -2°C.

3. Formulations

A formulation is a mixture that has been designed as a useful product. It is prepared using a specific "recipe" or formula so that it has a particular function.

• Key Feature: Each component in a formulation is present in a precise amount (specific proportions), and each contributes a different property to the final product.

• Examples of Formulations:

  • Fuels

  • Cleaning agents

  • Paints (contain pigments for color, binders to help it stick, etc.)

  • Medicines

  • Alloys

  • Fertilizers

  • Food and drink