Determination of Nitrate in water
AIM:
To determine the amount of nitrate ions present in a given sample by chromotropic acid method.
PRINCIPLE:
Nitrate ions react with chromotropic acid to form an unstable intermediate compound which further react with hydrogen sulphate ions to form a yellow product.
STEP 1:NO3 + chromotropic acid -----> unstable intermediate compound.
STEP 2:Unstable intermediate compound + HSO4- -----> yellow product.
The yellow product is a yellow color formation which increase with increase in nitrate ion concentration.
APPARATUS REQUIRED:
1)Standard volumetric flasks (10ml capacity).
2)Brown bottles.
3)UV Spectrophotometer.
4)Pipetts.
5)Blower.
CHEMICALS REQUIRED:
1)Chromotropic acid crystals.
2)Antimony metal powder.
3)Sulphuric acid.
4)Urea powder.
5)Reagent grade water.
6)Ice cold water.
Determination of total hardness in water.
REAGENTS AND PREPARATIONS:
1)Sulphite urea reagent:
Dissolve 5g of Urea poweder and 4g of anhydrous sodium sulphite in reagent grade water and make up to 1000ml in standard volumetric flask.
2)Antimony reagent:
Dissolve 500mg of antimony metal powder in 80ml of concentrated Sulphuric acid.then add 20ml ice cold water.
3)Chromotrophic acid reagent:
Dissolve 100mg of chromotropic acid crystals in 100ml concentrated sulphuric acid.store this solution in brown bottle.
PROCEDURE:
Take 2ml of sample in 10ml standard volumetric flask.add a drop of sulphite urea reagent.place the volumetric flasks to ice cold water.add 2ml of antimony reagent.let it stand for 4 minutes.add 1ml of chromotrophic acid reagent.then make up to 10ml mark with sulphuric acid.the appearance of yellow colour is directly proportional to the concentration of nitrate ions.after 45 minutes,read the absorbance in spectrophotometer at 410 nanometers.
Determination of ph and conductivity.
CALCULATION:
NO3 = A1 / A2 × S.C × 10 / 2
Where,
A1 = Sample absorbance of nitrate.
A2 = Standard absorbance of nitrate.
S.C = Standard concentration of nitrate.
10 = Constant (final make up volume).
2 = Constant (volume of sample taken).
EXAMPLE:
NO3 = 0.1532 / 0.5000 × 0.5 × 10 / 2 = 0.76mg/l.
Determination of Nitrite in water.
AIM:
To determine the amount of nitrite present in a given sample.
PRINCIPLE:
In acidic medium,nitrite ions react with sulphanilamaide to form diazonium compound.then N-(1Naphthyl)-ethylenediamine dihydrochloride react with that diazonium compound to form a pink colour compound which is detected by UV spectrophotometer at 543nanometers.
APPARATUS REQUIRED:
1)UV spectrophotometer.
2)Beakers.
3)Blower.
4)Pipetts.
5)Standard volumetric flasks (50ml capacity).
CHEMICALS REQUIRED:
1)Sulphanilamide.
2)NED dihydrochloride.(N-(1Naphthyl)-ethylenediamine dihydrochloride).
3)Reagent grade water.
4)Hydrochloric acid.
REAGENTS AND PREPARATIONS:
1)Sulphanilamide reagent:
Dissolve 5g of sulphanilamide in 50ml concentrated hydrochloric acid and add 300ml reagent grade water.
2)NED dihydrochloride reagent:
Dissolve 500mg of NED dihydrochloride reagent in 500ml reagent grade water.
Determination of sulphate and sulphite in water.
PROCEDURE:
Pour 50ml of samples in distilled water washed beakers.add 2ml of sulohanilamide reagent.wait for 2 to 8 minutes.then add 2ml of NED dihydrochloride reagent.the appearance of pink is directly proportional to the concentration of nitrite ions.after 8 minutes,read the sample absorbance at 543nm in uv spectrophotometer.
CALCULATION:
NO2 = Abs1 / Abs 2 × S.c × 50 / s.v
NO2 = Nitrite.
Abs1 = Sample absorbance of nitrite.
Abs2 = Standard absorbance of nitrite.
S.c = Standard concentration.
50 = Constant (final make up volume).
S.v = volume of sample taken.
EXAMPLE:
NO2 = 0.0143 / 0.0100 × 0.01 × 50 / 50 = 0.0143mg/l.
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