Distillation Techniques and Water Purification

This page covers distillation techniques, including simple and fractional distillation techniques, and their applications in water purification. It explains the principles behind these separation methods and their practical uses.

Simple distillation is described as a method used to separate a solvent from a solution, particularly effective when the dissolved solute has a much higher boiling point than the solvent. Fractional distillation, on the other hand, is explained as a technique to separate two or more liquids in a solution based on their different boiling points.

Example: In simple distillation, when a solution is heated, the solvent vapor evaporates, moves away, and is cooled and condensed, leaving behind a more concentrated solution of the solute.

The page also discusses the importance of using pure water for chemical analysis, noting that tap water contains dissolved salts that may interfere with reactions. It explains how simple distillation can be used to purify seawater by separating water from dissolved salts.

Highlight: Water used for chemical analysis should not contain salt, as tap water with dissolved salts may cause unexpected cloudy precipitation in reactions.

Methods of Separating and Purifying Substances

This page introduces the fundamental concepts of pure substances and mixtures, as well as the methods used to separate them. It covers the definitions of pure substances and mixtures, and explains how melting point data can be used to identify them. The page also delves into the filtration and crystallisation process, providing step-by-step methods for each technique.

Definition: A pure substance consists of only one element or compound and has a fixed composition, while a mixture contains two or more substances that are not chemically joined.

Highlight: Melting point data can be used to identify whether a substance is pure or a mixture. Pure substances have a single melting point, while mixtures have multiple melting points.

The filtration process is described as a method to separate an insoluble solid from a liquid using a physical barrier such as filter paper. The crystallisation process is explained as a technique to produce crystals from a solution by evaporating the solvent.

Vocabulary:

• Solute: The substance that is dissolved in a solvent
• Solvent: The liquid in which a solute is dissolved
• Filtrate: The liquid that passes through the filter during filtration