Tap water is not suitable for various laboratory purposes such as tests, solution preparation, equipment calibration, or glassware cleaning. Purified water is preferred in laboratories, and common methods include reverse osmosis, distillation, and deionization.
Distilled water, obtained through the distillation process, removes salts and particulates by boiling source water and condensing the steam. Deionized water, achieved through the removal of ions, is another purified form suitable for specific laboratory applications.
While both distillation and deionization eliminate ionic impurities, they are not interchangeable in the lab. The source water’s purity is crucial in distillation, with spring water commonly used. Some impurities, like volatile organics and mercury, can vaporize along with the water, emphasizing the importance of source water purity.
Difference between Distilled water and Deionized water are listed below:
| Characteristic | Distilled Water | Deionized Water |
|---|---|---|
| Production Method | Distillation (boiling and condensation) | Deionization (ion-exchange resins or other methods) |
| Purity | Relatively pure, removal of impurities through distillation | Highly purified, removal of both cations and anions |
| pH Level | Neutral (close to 7) | Slightly acidic due to the removal of ions |
| Applications | Laboratory experiments, medical procedures, household appliances | Laboratory work, manufacturing processes, industrial applications |
Significance of Distilled Water and Deionized Water
Distilled Water: Assuming the source water is tap or spring water, distilled water is pure enough for nearly all lab applications. It is used for:
- Solvent to prepare a solution
- Analytical blank
- Calibration standard
- Cleaning glassware
- Equipment sterilization
- Making high-purity water
Deionized Water: The purity of deionized water depends on the source water. Deionized water is used when a soft solvent is needed. It is used for:
- Cooling applications where it’s important to avoid depositing minerals
- Microbiology autoclaves
- Many chemistry experiments involving ionic compounds
- Washing glassware, especially the final rinse
- Solvent preparation
- Analytical blanks
- Calibration standards
- In batteries
Drinking Distilled and Deionized Water
Distilled water, though consumed by some, is not recommended as the primary choice for drinking water due to its lack of minerals found in spring and tap water, which contribute to better taste and health benefits. While it is acceptable to drink distilled water, deionized water is not advisable for consumption.
Deionized water lacks minerals, is corrosive, and can potentially harm tooth enamel and soft tissues. Moreover, deionization does not eliminate pathogens, making deionized water less effective in protecting against infectious diseases. However, after exposure to air, both distilled and deionized water can be safely consumed.
