Chemical Oxygen Demand (COD)
Apparatus -COD test tube, COD oil Bath, Beaker,Burette, condenser, Pipette
Chemical – Mercury sulfate (0.4g) ,Potassium Bicarbonate (0.2g), Sulfuric Acid (H2SO4), Ferron Indicator, Distill Water.
Sample – Stone Four Sample (Grey, Poly, Drink Water).
COD – chemical oxygen demand.
COD is a measured of the capacity of to consume oxygen during decomposition of organic matter & Oxidation of inorganic chemical such as Ammonia & nitrite.
COD test is used to amount of organic compound in a water sample.
- Firstly washed COD four test tube
- Add into the 2 to 3 piece of stone.
- Add Mercury sulfate (4g) ineach tube.
- Then add (40ml) distill water in only blank tube and other three tube in (20ml) distill water.
- Add three tube (Grey,KHP,PABAL WATER) in (20ml)distill water.
- Then again add the (30ml) sulfuric acid.
- Then this four tube put in the COD oil Bath for (2hours).
- After heating take out tube in the oil Bath and put the cool tube for (30min).
- After cooling add 150ml distill water and add one drop of ferron indicator in each tube.
- Then do the titration until come to the brown colour of the sample.
COD = (Blank-sample)*0.255*8000/20
PABAL WATER – (7.8- 6.8)*0.255*8000/20 = 102
GREY -(7.8- 6.8)*0.255*8000/20 = 367.
KHP – (7.8-6.8)*0.255*8000/20 = 499