# Civil Engineering - UPSC Civil Service Exam Questions - Discussion

42.

A sample of ground water at a pH of 7.0 contains 122 mg/l of bicarbonates. What is the alkalinity of this water (in terms of CaC0 ) ?

 [A]. 120 mg/1 [B]. 60 mg/1 [C]. 100 mg/1 [D]. 200 mg/l

Explanation:

No answer description available for this question.

 Vikram Syal said: (Mar 5, 2018) bicarbonate means hco3 negative, equivalent wt of HCO3 IS 2. No of gram equivalent = given wt./equivalent wt of ca2co3 50. Given wt.= 2*50 = 100.

 Mudassir said: (Apr 28, 2019) Equivalent of hco3 is 1. So, 1*50 will be 50.

 Mohammad Rizwan said: (Nov 19, 2019) Alkalinity, in this case, can be calculated as, amount of sample in mg/L * (Equivalent wt of CaCo3/Equivalent wt of ion). Here, Amount of Sample = 122mg/L. Equivalent wt of CaCO3 = 50. Equivalent wt of HCO3-- = 61. Therefore : 122*(50/61)=100mg/L as CaCO3. Also, Eq wt can be calculated as, Eq Wt= Molecular Wt/Valancy. Eq wt of CaCO3 = 100/2. Wq wt of HCO3- = 61/1. Molecular wt of HCO3-= (1+12+(16*3)) = 61.