Tue. Jul 16th, 2019


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What Is The Difference Between Heavy Water And Hard Water?

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Water acts as an excellent universal solvent. The primary difference between hard water and heavy water is hard water contains dissolved salts in it and does not lather readily with soap. Hard water originates from seas, rivers, wells, springs etc. on the other hand heavy water is deuterium oxide (D2O). Urey discovered heavy water and proved that ordinary water contains one part of heavy water in 6000 parts in it.

Another type of water is soft water which is free from the dissolved salts and lathers readily with soap. Soft water is present in rainwater or distilled water. Water can be easily prepared by combining hydrogen and oxygen with the help of electric current where for every one part of hydrogen eight parts of oxygen are required.

What is Heavy Water?

Heavy water is the oxide of heavy hydrogen (deuterium) and is also called deuterium oxide. Heavy water is chemically similar to ordinary water. Lewis and Donald in 1933 were able to isolate a few millilitres of heavy water by the prolonged electrolysis of alkaline water.

Heavy water is used as a neutron moderator and for the preparation of deuterium and as a tracer compound. Heavy water has some biological and physiological effects. High concentration of heavy water retards the growth of plants and animals. Pure heavy water kills small fishes, tadpoles and mice when fed with it. On contrary water containing a small quantity of D2O acts as a tonic and simulates vegetable growth.

Hard Water Types

There are two types of hard water.

  1. Temporary hardness
  2. Permanent hardness

Temporary hardness – This is due to the presence of bicarbonates of calcium and magnesium. The formation of bicarbonates in water is due to the dissolution of carbon dioxide of the atmosphere in rainwater which falls on rocks containing calcium carbonate as magnesium carbonate.

Permanent hardness – This is due to the presence of soluble sulphates and chlorides of magnesium and calcium. These are present in hard water due to the dissolution of rocks containing the sulphates and chlorides of both calcium and magnesium.

Water Softeners

A water softener is a device that uses sodium chloride that is common salt to treat hard water. Minerals such as calcium, magnesium, manganese and iron that are present in hard water are drawn up in the underground water supply and after heating; they crystallize and stubbornly stick to utensil surfaces. Sodium chloride the effective component of water, softeners acts to remove these unwanted minerals.

Hence, these were some differences between hard water and heavy water. Students who are interested to learn more fun facts can subscribe to our BYJU’S YouTube Channel.