Deionized vs Distilled water
Water covers more than 70% of the earths’ surface. Out of this, a larger portion of water is in the oceans and seas, which is about 97%. Rivers, lakes, and ponds have 0.6% of water, and about 2% is there in polar ice caps and glaciers. Some amount of water is present in the underground, and a minute amount is in the gas form as vapors and clouds. Among this, there is less than 1% of water left for direct human use.
Water is used for many purposes in a laboratory. Water from rivers, lakes, or ponds contains many things such as microorganisms, suspended particles, ions, dissolved gases, etc. Rainwater also contains many other things except water molecules. Even the tap water, which is distributed after purification, has many dissolved compounds. These dissolved compounds may change the properties of the water. Water is a clear, colorless, tasteless, and odorless liquid. Pure water should have a neutral pH, whereas the water we are taking from various sources may be slightly acidic or basic. However, due to the impurities in the water, we cannot use them for certain purposes. In experiments, where accurate measurements have to be taken, purified water should be used. For example, if an acidity of a sample has to be measured in a titrimetric method, then very pure water should be used in the process from cleaning the glassware to making solutions, etc. Otherwise, using normal water will give an error in the measurements. Deionized water and distilled water are pure forms of water to use in such occasions.
This is a type of purified water in which all minerals have been removed. Mineral ions like sodium, calcium, chloride, bromide are present in natural water and are removed in the deionization process. In this process, normal water is send through an electrically charged resin that attracts and retains the mineral ions. However, this method only removes charged ions and does not remove microorganisms, other uncharged particles and impurities present in the water.
In distilled water, the impurities are removed during distillation process. The basis of distillation relies on the fact that other molecules and microscopic impurities in the water are heavier than the water molecules. Therefore, when distilling, only water molecules will evaporate. Water boils at 100 oC and water molecules will evaporate. Water steam is then allowed to travel inside a condensation tube where flow of water will absorb the heat in steam and make it condensed. Then the condensed water drops can be collected into another clean container. This water is known as distilled water. Distilled water should contain only water molecules without any bacteria, ions, gases, or other contaminants. It should have a pH of 7, which indicated that the water is neutral. Distilled water has no taste since all the minerals have been removed. However, it is safe to drink. However, distilled water is mainly used for the research purposes.
What is the difference between Deionized Water and Distilled Water?
• When preparing deionized water, normal water is sent through a charged resin column. Distilled water is prepared by distillation process.
• There are no mineral ions in deionized water; however, there can be other impurities and bacteria. In distilled water, most of the other impurities also are removed, and the water is more purified than deionized water.