Join 60,000+ competitive exam aspirants
or with email
Your Cart
SubtotalтВ╣0
TotalтВ╣0
Examoogle тАв User тАв info@examoogle.com тАв EE-2024-8821
Chapter 1 of 12 тАв Page 1 of 248ЁЯФТ Protected PDF тАв Watermarked
Join 60,000+ competitive exam aspirants
Which chemical is commonly used to soften hard water by precipitating calcium and magnesium ions?
Sodium carbonate
Sodium chloride
Calcium hydroxide
Magnesium sulfate
Sodium carbonate
Sodium carbonate, commonly known as washing soda, is used to soften both temporary and permanent hard water. It removes hardness by precipitating the soluble calcium and magnesium ions as insoluble carbonates.
Sodium carbonate, commonly known as washing soda, is used to soften both temporary and permanent hard water. It removes hardness by precipitating the soluble calcium and magnesium ions as insoluble carbonates.
Think of it like a bouncer at a club who identifies the unwanted 'troublemakers' (calcium and magnesium ions) and forces them to settle down outside (precipitate) so the 'party' (the water) can remain clean and soft.
NaCO3 (Sodium Carbonate) = Water Softening Hero.
Ca2++Na2тАЛCO3тАЛтЖТCaCO3тАЛтЖУ+2Na+ тАФ precipitation of calcium carbonate
Mg2++Na2тАЛCO3тАЛтЖТMgCO3тАЛтЖУ+2Na+ тАФ precipitation of magnesium carbonate
The process is known as the soda process. When sodium carbonate is added to hard water, it reacts with the dissolved calcium and magnesium salts (chlorides, sulfates, or nitrates) to form insoluble precipitates of calcium carbonate and magnesium carbonate, which can then be removed by filtration.
Permanent hardness is caused by chlorides and sulfates of Calcium and Magnesium.
Sodium carbonate is effective for large-scale industrial water treatment.
The process removes the ions that prevent soap from forming a lather.
Efficiently removes permanent hardness.
Cost-effective for large-scale applications.
Produces sludge (precipitates) that must be filtered out.
Can increase the alkalinity of water if used in excess.
Industrial boiler water treatment.
Domestic water softening using washing soda.
Sodium carbonate is represented as Na2тАЛCO3тАЛ.
Option B (Sodium chloride) is common salt and does not remove hardness.
Option C (Calcium hydroxide) is used in Clark's process to remove temporary hardness.
Option D (Magnesium sulfate) is actually a cause of permanent hardness, not a remover.
A is correct тАФ Sodium carbonate reacts with soluble hardness-causing ions to form insoluble carbonates, thereby removing them from the water.
Always distinguish between Clark's method (using slaked lime for temporary hardness) and the Soda process (using washing soda for permanent hardness) for exams.