SHANMUGANATHAN ENGINEERING COLLEGE
1. What are the salt responsible for carbonate & non-carbonate hardness of water?
Carbonate hardness: Ca(HCO)2 and Mg(HCO)2
It give wine red colour with EBT indicator It does not give colour with EBT indicator
3. How hardness of water is expressed?
The concentration of hardness producing salts are usually expressed interms of an equivalent
amount of CaCO3
6. Calculate the hardness of a water sample containing 2.4 mg of CaCl2 in 500 ml of water.
The amount of CaCl2 =2.4 mgs/500 ml
Reg. No.
Internal Conditioning External Conditioning
Its carried out with in the boiler Its carried out before feeding the water into the boiler
It is used for low pressure boilers It is used for high pressure boilers
(or)
The amount of CaCl2 =4.8 mgs/1 lit
Molecular weight of CaCl2 = 111
Amount equivalent to CaCO3 = X x molecular weight of CaCO3
molecular weight of hardness producing substance
Amount equivalent to CaCO3 = 4.8 x 100
111
= 4.324 mgs/lit
PART -B (1 x 13 = 13)
7. (a) Explain the EDTA method of estimation of hardness of water (13) Formula (2)
Principle (2) Procedure (5)
Calculation (4)
(OR)
(b) (i) How is internal treatment of boiler water carried out using Phosphate and Sodium
aluminate conditioning. (08) Phosphate conditioning (4)
Sodium aluminate conditioning (4) (ii) What are Scale and Sludges . Describe the disadvantages of scale formation. (05) Scale (3)
Sludge (2)
