Estimation of Free CO2 in Water: Practical Approach
Estimation of free CO2 in water samples is a crucial aspect of environmental analysis. This practical guide covers the methodology using NaOH and Na2CO3 titration methods, along with detailed procedures, reagent details, and observation tables for accurate results. The process involves the conversion of free CO2 to sodium bicarbonate and the use of phenolphthalein indicator for endpoint detection. Understand the calculations involved for determining chloride content in water samples through titration.
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Presentation Transcript
Estimation of Free CO2 in given Water Sample Class- B.Sc. III Year Practical Date: 15.10.2020 Time: 03:00-05:00PM Presented by Manoj Joshi Department of Zoology UCoS,MLSU, Udaipur.
CO2 present in water is called free CO2. Free CO2 react with H2O and form carbonic acid which is titrated with strong base (NaOH) or weak base (Na2CO3). Carbonic acid convert into nutral sodium bicarbonate, by adding phenolphtalin indicator during titration at pH 8.3 it gives pink colour. 2NaOH + CO2=== Na2CO3 + H2O Na2CO3 + H2O + H2O + CO2 == 2NaHCO3. Free CO2 titratte by two methods:- (a) NaOH (b) Na2CO3
(a) By NaOH:- Reagents:- i. 0.05 N NaOH:- 40 gm + 1000 ml DW Heat and then Cool. ii. Phenolpthalien:- 50 ml 95% Ethenol + 500 mg Phenolpthalien. Procedure:- Collect 250-300 ml sample in Nessler tube carefully. Take 100 ml sample from collected sample in a conical flask. Add few drops of indicator if it shows pink colour then no free CO2 present in sample. If it remain colourless then titrate it up to pink colour appearance. Note the reading and repeat the process three times for better results.
Observation table:- Burette Reading End Sample Vol. (ml) S. No Mean Start 0.0 0.0 0.0 Total 1 2 3 100 100 100 Calculation:- Chloride mg/L= A x N of NaOH X 1000 x 44 ml of sample = A x 0.05 x 1000 x 44 100 = A x 22mg/L.
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