Question

1. In the determination of the alkalinity of a wastewater sample, we have the following data

Final pH = 3.9

   Volume of H2SO4 0.2 N used in the titration = 4.95 mL

Multiplier = 20

Alkalinity in terms of bicarbonate HCO3^- = 97.23

Determine:

1. the total alkalinity (use the equations)
2. % error compared whit the experimental result
3. the alkalinity in terms of hydroxide

Answer 1

Answer :

Given that  sample is titrated with 0.2 N sulphuric acid and 4.95 ml of titrant was used as the end point.

(a) For calculating    the total alkalinity :

The concentration is = 4.95* 20 = 9.90 mg/ l as CaCO3 phenolphthalein alkalinity

* The total alkalinity = 4.9

(B) For calculating % error :

% error = (4.9 - 3.9)/ 4.9

*   % error = 20.40 %

(c) For calculating Alkalinity in terms of hydroxide   :

Alkalinity in terms of hydroxide

= (P alkalinity * 2) - total alkalinity

= 9.9 * 2 - 4.9

= 14.9

* Alkalinity in terms of hydroxide = 14.9