User:Velayudham T/sandbox

1.DETERMINATION OF CHLORIDE CONTENT IN WATER

PRINCIPLE: This method is based on the precipitation and titration in which from the burette silver nitrate solution is released to the chloride ions and indicator containing water sample. The silver ions will react with chloride ions and the chromate ions to form white precipitate of silver chloride and red precipitate of silver chromate.

Ag+ + Cl–               AgCl (white precipitate)

2Ag+ + CrO42-                    Ag2CrO4 +   CrO42- (red precipitate)

CHEMICALS: Silver Nitrate (0.1 N)	Potassium Chromate ( 5 %) Distlled water GLASSWARES : Burette 50 ml	Pipette 1 ml	Conical flask 250 ml	Measuring cylinder 50 ml PROCEDURE: Take 25 ml of test sample ( water) in a 250 ml conical flask. Add 1 ml of 5% potassium chromate solution to this. Mix well and titrate against 0.1 N silver nitrate solution. The end point is yellow to brown colour appearance.

CALCULATION:

Chloride = (T.V ×N of AgNo3)/25 × 35.45 × 1000 Mg/Ltr.

2.DETERMINATION OF TOTAL ALKALINITY IN WATER

PRINCIPLE: Alkalinity of water means the total content of those substances in it which causes an increased OH- ion concentration up on dissociation or due to hydrolysis. The alkalinity of water is attributed to the presence of	Caustic alkalinity ( Due to OH- and CO32- ) Temporary hardness ( Due to HCO3- ) Alkalinity is a measure of ability of water to neutralize the acids. P = OH- + 1⁄2 CO32- M = OH- + CO32- + HCO3- CHEMICALS : Hydrochloric acid 0.1 N	Phenolphthalein indicator Methyl orange indicator GLASSWARES : 50 ml Burette Pipette Conical flask Funnel Measuring cylinder PROCEDURE: Take 20 ml of test sample ( water ) in a 100 ml conical flask. Add 4-5 drops of phenolphthalein indicator to this. To titrate against 0.1 N Hydrochloric acid till the pink colour disappear. Again add 4-5 drops of methyl orange indicator to the same flask. To titrate against the 0.1 N Hydrochloric acid the colour turns orange to yellow. CALCULATION: Phenolphthalein Alkalinity (P) = (V1 × N × 50 × 1000)/V  Mg/ltr

Methyl Orange Alkalinity (M) = (V2 × N × 50 × 1000)/V Mg/ltr Here: V = Total volume of sample used. V1 = ml of standard HCL used for discolouring of phenolphthalein indicator. V2 = ml of standard HCL used for Methyl orange end point. N  = Normality of Hydrochloric acid. Alkalinity relationship table: Result of titration	Hydroxide alkalinity as CaCo3	Carbonate alkalinity as CaCo3	Bicarbonate alkalinity as CaCo3 P = 0	0	0	T P < 1⁄2 T	0	2P	T – 2P P = 1⁄2 T	0	2P	0 P > 1⁄2 T	2P – T	2 ( T – P )	0 P = T	T	0	0

P = Phenolphthalein Alkalinity. T = Total Alkalinity

3.DETERMINATION OF TOTAL DISSOLVED SOLIDS IN WATER

PRINCIPLE: The removal of  the water content of a compound can be determined by vaporizing the water using thermal energy (heat). Heat can also be used, if oxygen is present, for combustion to isolate the suspect species and obtain the desired results of mineral residues. EQUIPMENTS: Glass beaker 50 ml. Analytical Balance. Hot plate. Hot air oven. Pipette 10 ml. PROCEDURE: To take the 10 g of test sample ( water ) in a 50 ml of weighed beaker. Keep boiling to evaporate the water from beaker on hot plate. Then keep it into the hot air oven 1 hour at 100°c for removal of excess moisture. Then remove the beaker from oven and cool it at room temperature. After cooling weigh it and note down the beaker weight and calculate the TDS. CALCULATION:

TDS = (Dry Weight of the beaker ­ Empty Weight of the beaker)/(Sample weight) ×10×10×10×10×10×10 ppm

4.DETERMINATION OF HARDNESS OF WATER

PRINCIPLE: The estimation of water hardness is based on complexometric titration. The hardness of water is estimated by the titration against EDTA using Erichrome black-T as an indicator. Initially EBT forms a weak EBT Ca2+ / Mg2+ wine red coloured complex with Ca2+ / Mg2+ ions present in the hard water. On addition of EDTA solution, Ca2+ / Mg2+ ions preferably forms a stable EDTA - Ca2+ / Mg2+  complex with EDTA leaving the free EBT indicator in solution which is steel blue in colour in the presence of ammonia buffer.

Eriochrome Black-T + Ca2+ /Mg2+ → Eriochrome Black-T-Ca2+ /Mg2+  (Wine red) Eriochrome Black-T-Ca2+ /Mg2+ + (Wine red) + EDTA  →  EDTA- Ca2+ /Mg2+  + Eriochrome Black-T (Steel blue) CHEMICALS: Ammonium Chloride Ammonium Hydroxide Ethyline Diamine Tetra Acetic Acid ( EDTA ) Erichrome Black – T ( EBT ) Ethyl Alcohol ( Ethanol ) Distlled water GLASSWARE: 50 ml measuring cylinder 250 ml conical flask 2 ml pipette 1 ml pipette 50 ml burette

PROCEDURE: To take the 50 ml of test sample ( water ) in a clean 250 ml of conical flask. Add 2 ml of Ammonia Buffer to the flask and mix it. Add 0.1 or 0.2 ml of EBT indicator to the conical flask. To titrate against the standard burette solution of EDTA. The end point is wine red to steel blue colour appearance. Note the burette reading and calculate the total hardness of the water sample.

CALCULATION:

Total Hardness = (Titration Value ×1000)/50 ppm

CHEMICAL PREPARATION: 1.Standard EDTA (Ethyline Diamine Tetra Acetic Acid ) To take 3.798 g of EDTA in a 1000 ml of beaker add 1ltr of distilled water to this and mix with a glass rod it is 0.01 N of EDTA preserve it in a closed glass container. 2.Ammonia Buffer: Take 16.9 g of Ammonium Chloride in a 500 ml beaker and take add 250 ml of distilled water put it on magnetic stirrer mix well and then add slowly con.Ammonia solution to this measure the ph of the mixing solution the ph comes 10 then stop adding the Ammonia solution adding it takes approximate 143 ml of Ammonia solution. Then preserve it in a closed glass container. 3. Eriochrom Black – T : To take 100 ml of Ethanol in a glass bottle add 0.5 g of Eriochrom Black – T into that and mix it well it is 0.5 % of EBT solution.