Why is soda ash needed in the treatment of water?

• A. To balance the water's temperature
• B. To serve as additional carbonate for forming calcium carbonate
• C. To enhance disinfection
• D. To improve taste

Answer: (B)

Soda ash, chemically known as sodium carbonate, plays a significant role in water treatment, particularly in the process of softening water. One of its primary functions is to provide additional carbonate ions that react with calcium ions present in the water. This reaction leads to the formation of calcium carbonate, which precipitates out of the solution. The precipitation of calcium carbonate is essential as it helps to reduce hardness in water, making it more suitable for domestic and industrial use. By lowering water hardness, soda ash enhances the effectiveness of detergents and other cleansing agents, while also minimizing scale buildup in pipes and equipment.

While soda ash can have minor effects on other aspects of water treatment, such as slight adjustments in temperature and possibly improving the taste, its main purpose lies in its ability to assist in the formation of calcium carbonate for the softening process. Its contribution to enhancing disinfection is not a primary function, as that is generally achieved through other methods, such as the use of chlorine or UV treatment. Thus, the most accurate reason soda ash is included in water treatment processes is its role in providing additional carbonate for the formation of calcium carbonate, helping to manage water hardness effectively.