1st Exam Revision Flashcards
What happens when water is heated above 70°C?
Bicarbonate converts into calcium carbonate, which precipitates out and releases carbon dioxide
This method is used for reducing bicarbonate levels and removing hardness.
What is the key sign of the heating method in decarbonation?
Scaling (calcium deposits) forms as a result
This indicates the precipitation of calcium carbonate.
What is the chemical formula for lime used in treatment?
Ca(OH)₂
Lime treatment is effective in softening water and removing bicarbonate and metals.
How does lime treatment work?
It reacts with bicarbonate to form calcium carbonate, which precipitates, and removes iron, manganese, and heavy metals
This method is used for softening water.
What is the effect of acid addition in decarbonation?
It reacts with bicarbonate, releasing CO₂ and forming calcium
This method is used to reduce alkalinity.
What is the function of Weakly Acidic Cation (WAC) exchange?
WAC resins swap hydrogen ions for calcium and magnesium in bicarbonate-rich water
This process helps in de-alkalizing water and removing temporary hardness.
What does Strongly Acidic Cation (SAC) exchange do?
Removes all metal cations at any pH and replaces them with hydrogen ions
This leads to pH reduction and converts bicarbonate into carbonic acid.
What is the purpose of Nanofiltration (NF)?
Partial demineralization and de-alkalization
NF uses membrane filtration at 0.001μm to remove organics and 20-80% of dissolved salts.
How does Reverse Osmosis (RO) work?
High-pressure membrane filtration removes most dissolved ions and problem compounds
This method achieves almost complete removal of alkalinity, minerals, and contaminants.
Fill in the blank: Heating water above 70°C converts bicarbonate into _______.
calcium carbonate
True or False: Acid addition increases alkalinity by adding bicarbonate.
False
