Determination of Sulphate and Sulphide - New Age International
Determination of Sulphate and Sulphide - New Age International Determination of Sulphate and Sulphide - New Age International
50 A Comprehensive Laboratory Manual for Environmental Science and Engineering Calculation Results mg of BaSO SO 4 in mg/L = 4 411.6 mL of sample × =......... Sample no. or description mg/L of SO 4 Discussion B. DETERMINATION OF SULPHIDE Aim To determine the amount of sulphide present in the sample by titrimetric method. Principle Sulphides often occur in ground water especially in hot springs, in wastewater and polluted waters. Hydrogen sulphide escaping into the air from sulphide containing wastewater causes odour nuisance. It is highly toxic and cause corrosion of sewers and pipes. Sulphides include H 2 S and HS – and acid soluble metallic sulphides present in the suspended matter. Iodine reacts with sulphide in acid solution, oxidising it to sulphur; a titration based on this reaction is an accurate method for determining sulphides at concentration above 1mg/L if interferences are absent and if loss of H 2 S is avoided.
Determination of Sulphate and Sulphide 51 Apparatus 1. Burette 2. Pipette 3. Erlenmeyer flask. Reagents 1. Hydrochloric acid 2. Standard iodine solution (0.025N) 3. Standard sodium thiosulphate solution (0.025N) 4. Starch solution Procedure 1. Measure from a burette 10mL of iodine into a 500 mL flask. 2. Add distilled water and bring the volume to 20 mL. 3. Add 2 mL of 6 N HCl. 4. Pipette 200 mL sample into the flask, discharging the sample under the surface of solution. 5. If the iodine colour disappears, add more iodine so that the colour remains. 6. Titrate with sodium thiosulphate solution, adding a few drops of starch solution, as the end point is approached and continuing until the blue colour disappears. Observation Sample no. or Volume of iodine Volume of sodium Volume of mg/L description solution used (a mL) thiosulphate solution sample used sulphide used (b mL) Calculation mg/L sulphide = 400 (a – b) mL of sample where, a = mL 0.025 N iodine used b = mL 0.025 N sodium thiosulphate solution used.
- Page 1 and 2: Experiment No. ___________________
- Page 3: Determination of Sulphate and Sulph
50 A Comprehensive Laboratory Manual for Environmental Science <strong>and</strong> Engineering<br />
Calculation<br />
Results<br />
mg <strong>of</strong> BaSO<br />
SO 4<br />
in mg/L =<br />
4<br />
411.6<br />
mL <strong>of</strong> sample × =.........<br />
Sample no. or description mg/L <strong>of</strong> SO 4<br />
Discussion<br />
B. DETERMINATION OF SULPHIDE<br />
Aim<br />
To determine the amount <strong>of</strong> sulphide present in the sample by titrimetric method.<br />
Principle<br />
<strong>Sulphide</strong>s <strong>of</strong>ten occur in ground water especially in hot springs, in wastewater <strong>and</strong> polluted waters. Hydrogen<br />
sulphide escaping into the air from sulphide containing wastewater causes odour nuisance. It is highly toxic <strong>and</strong><br />
cause corrosion <strong>of</strong> sewers <strong>and</strong> pipes. <strong>Sulphide</strong>s include H 2<br />
S <strong>and</strong> HS – <strong>and</strong> acid soluble metallic sulphides present in<br />
the suspended matter.<br />
Iodine reacts with sulphide in acid solution, oxidising it to sulphur; a titration based on this reaction is an<br />
accurate method for determining sulphides at concentration above 1mg/L if interferences are absent <strong>and</strong> if loss <strong>of</strong><br />
H 2<br />
S is avoided.
Change language