How to Prepare Chemical Laboratory Water by Distillation?

Distilled water is pure water obtained by distillation, utilizing the difference in boiling points between water and its impurities. Many types of distillation apparatus are used to prepare distilled water; currently, internally heated distillation apparatuses are more commonly used than externally heated methods such as electric furnaces, gas stoves, or coal stoves. Laboratory distillation apparatuses are typically made of glass or metal. Distilled water still contains trace amounts of impurities.

There are two reasons:

1. Carbon dioxide and certain low-boiling-point volatile substances are carried into the distilled water with the water vapor;

2. Trace amounts of components from the materials of the condenser, distillation apparatus, and container are also introduced into the distilled water. Water used in chemical laboratory analysis is usually obtained through single distillation, known as first-grade distilled water. Some analyses require water obtained through double or triple distillation. For the analysis of high-purity substances, ultrapure water is essential. To achieve this, ultrapure water can be produced by increasing the number of distillations, slowing down the distillation rate, discarding the first and last distillates, and using distillation apparatus made of special materials such as quartz, silver, platinum, or polytetrafluoroethylene. Ultrapure water cannot be stored in glass containers but should be stored in plexiglass, polyethylene, or quartz containers.

Commonly used glassware for distillation is readily available in the market, including single- or double-distilled glass water distillers, suitable for general small and medium-sized laboratories. Distillation is a simple and convenient method for preparing laboratory water, widely used in laboratories.