Question

Why is distilled water considered to be the purest form of water?

Answer 1

Hint: We should recall the concept of distillation process. We should know that distillation is the process of separating the components or substances from a liquid mixture by using selective boiling and condensation.

Complete step by step solution:
We should know that distilled water is water that has been boiled into vapour and condensed back into liquid in a separate container. Impurities in the original water that do not boil below or near the boiling point of water remain in the original container. Thus, distilled water is one type of purified water.

We should know that distillation is one of the oldest methods of water treatment and is still in use today, though not commonly as a home treatment method. It can effectively remove many contaminants from drinking water, including bacteria, inorganic and many organic compounds. As we know that distillation relies on evaporation to purify water. Contaminated water is heated to form steam. Inorganic compounds and large non-volatile organic molecules do not evaporate with the water and are left behind. The steam then cools and condenses to form purified water. We know that distillation effectively removes inorganic compounds such as metals (lead), nitrate, and other nuisance particles such as iron and hardness from a contaminated water supply. The boiling process also kills microorganisms such as bacteria and some viruses.

Working: Now, we should know about working the distillation process. We should know that distillation is a water purification process that uses a heat source to vaporize water and separate it from the contaminants within. Most frequently, the undesirable elements are what we find naturally in ground or surface water.

We should know that distillation heats untreated water until the water reaches its relatively low boiling point and begins to vaporize. The heat of the water is then kept at this temperature to maintain the water vaporization while stopping other elements from vaporizing as well. This process also helps to separate the water molecules from any microscopic disease-causing organisms. Once, the water has vaporized, that vapour is then funnelled into a condenser. Removed from the heat source, the water cools and reverts back to its liquid form and flows into a receiving container. This water is a purified form of water.
So, from above reasons we can say that distilled water is the purest form of water.

Note: It should be noted that distillation's effectiveness in removing organic compounds varies, depending on such chemical characteristics of the organic compound as solubility and boiling point. Organic compounds with boiling points lower than the boiling point of water (ex. benzene and toluene) vaporize along with the water. These harmful compounds will re-contaminate the purified product if not removed prior to condensation.