Determination of sulphate in water
AIM:
To determine the amount of sulphate present in a given sample by gravimetric method.
PRINCIPLE:
This is gravimetric method in which the sulphate ions present in the water that react with barium chloride to precipitate as barium sulphate that measured by uv spectrophotometer.
SO4 + BaCl2 ------> BaSO4 + 2Cl-
APPARATUS REQUIRED:
1)UV spectrophotometer.
2)Standard volumetric flasks.
3)Pipetts.
4)Spatula.
5)Glass rods.
6)Blowers.
7)Beakers.
CHEMICALS REQUIRED:
1)Hydrochloric acid.
2)Glycerol.
3)Sodium chloride.
4)Isopropyl alcohol.
5)Reagent grade water.
6)Barium chloride.
REAGENTS AND PREPARATIONS:
1)Conditioning reagent:
Dissolve 75g of sodium chloride in 300ml reagent grade water.add 100ml iso propyl alcohol and 30ml concentrated hydrochloric acid.mix this solution with 50ml glycerol.
2)1:9 HCL.
Mix 10ml of concentrated hydrochloric acid with 90ml reagent grade water.
Determination of total hardness in water.
PROCEDURE:
Dilute the sample to 100ml in standard volumetric flask.pour in to beaker.add 1ml of 1:9 HCL and 1ml of conditioning reagent.add a spatula of barium chloride.barium chloride precipitate as barium sulphate if sulphate ions present.the appearance of white turbid is directly proportional to sulphate ions concentration.after 10 minutes,read the absorbance at 420 nm in UV spectrophotometer.
CALCULATION:
Abs 1 / Abs 2 × C × D / S.v
Abs 1 - Sample absorbance.
Abs 2 - Standard absorbance.
C - Standard concentration.
D - final diluted volume.
S.v - Sample taken volume.
MODEL CALCULATION:
SO4 = 0.2882 / 0.2046 × 25.0 × 100 / 50 = 70.43mg/l.
Determination of PH and electrical conductivity of water.
Determination of Sulphite in water.
AIM:
To determine the amount of sulphite present in a given sample by Iodometric titration method.
PRINCIPLE:
STEP 1:When iodate is added to a solution containing sulphite ions,the product will be iodide and sulphate ions.this is slow reaction.
IO3- + 2SO3 2- -------> I- + 2SO4 2-
STEP 2: the iodate ions further react with product of iodide ions to form iodine and 3 moles of water in acidic medium.this is fast reaction.
IO3- + 5I- + 6H+ --------> 3I2 + 3H2O
STEP 3: the iodine react with Sulphite ions and water.this is very fast reaction in which all the sulphite ions converted to sulphate ions.and end point occurred.
I2 + SO3 2- + H2O --------> SO4 2- + 2I- + 2H+
Determination of chloride in water.
APPARATUS REQUIRED:
1)Iodine flasks (250ml capacity).
2)Standard volumetric flasks.
3)Pipetts.
4)Burette.
5)Glass rods.
6)Spatula.
7)Weighing balance.
CHEMICALS REQUIRED:
1)Sulphuric acid.
2)Sulphamic acid.
3)Starch.
4)Potassium Iodate.
5)Reagent grade water.
6)Potassium iodide.
7)Disodium salt of EDTA.
8)Chloroform.
9)Sodium bicarbonate.
REAGENTS AND PREPARATIONS:
1)Starch indicator:
Dissolve 5g of starch in 800ml boiled reagent grade water.then make up to 1000ml in standard volumetric flask.
2)EDTA solution:
Dissolve 2.5g of disodium salt of EDTA in 100ml distilled water.
3)Standard 0.0125M Iodate - iodide solution:
Dissolve 0.4458g of potassium Iodate and 4.35g of potassium iodide in distilled water.add 310mg of sodium bicarbonate.Dilute this solution to 1000 ml.
PROCEDURE:
Adjust the sample PH below to 8.00.heat the sample to 50 degree Celsius and add 1ml of EDTA solution.take a 250 ml long necked iodine flask. add 1ml of sulphuric acid and 0.1g of sulphamic acid crystals.add the 100ml diluted sample aliquot and 1ml of starch indicator.then start titration immediately against 0.0125 Iodate-iodide solution.the emd point is pure blue.note the burette reading.
Determination of calcium and magnesium in water.
CALCULATION:
SO3 = (V2 - V1) × N × 40 × 1000 / S.v
SO3 - Sulphite.
V1 -burette reading of blank.
V2 - Final burette reading.
N - Normality of Iodate - iodide solution.
40 - Equivalent weight of sulphite.
1000 - For milligram conversion.
MODEL CALCULATION:
SO3 = (4.0 -0.0) × 0.0125 × 40 × 1000 / 100 = 20mg/l.
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