Question
Download Solution PDFWhat does Chemical Oxygen Demand (COD) indicate?
Answer (Detailed Solution Below)
Detailed Solution
Download Solution PDFExplanation:
(i) The COD (Chemical oxygen demand) test is used to measure the content of organic matter of waste water, both biodegradable and non-biodegradble. So, we can say that COD determines the strength of sewage
(ii) The COD test uses potassium dichromate (K2Cr2O7) in presence of concentrated sulfuric acid (H2SO4) solution that oxidizes both organic (predominate) and inorganic substances in a waste water sample.
(iii) The reagents for COD test are followings:
- Standard potassium dichromate solution (0.25N)
- Concentrated sulfuric acid
- Standard ferrous ammonium sulphate titrant (0.1N)
- Ferroin indicator solution.
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