Question

GIVE THE Chemical oxygen demand (COD)

Glucose :

Dihydrogen ( H₂):

NH₄⁺ :

Answer 1

For these systems we have to conside that the theoretical oxygen demand is the chemical oxygen demand

The basis for the COD test is that nearly all organic compounds can be fully oxidized to carbon dioxide with a strong oxidizing agent under acidic conditions. The amount of oxygen required to oxidize an organic compound to carbon dioxide, ammonia, and water is given by:

For Glucose the formula is C6H12O6 so the amount of oxygen required will be

C6H12O6 + 6O2 ----> 6CO2 + 6H2O

1 mole of glucose requires 6 moles of oxygen

6 x 32 g of oxygen react with 180 g of glucose

192 g of oxygen react with 180 g of glucose

1.0667 g of oxygen react with 1 g of glucose.

For hydrogen the equation is

2H2 + O2 -------> H2O

2 moles of hydrogen react with 1 mole of oxygen

32 g of oxygen react with 4 g of hydrogen

8 g of oxygen react with 1 g of hydrogen.

For NH₄⁺ the equation is

NH₄⁺ + 2O₂ ---------> NO₃^- + 2H⁺ + H₂O

So 1 mole of NH₄⁺ reacts with 2 moles of oxygen

32 x 2 g of oxygen reacts with 18 g of ammonium

3.556 g of oxygen reacts with 1 g of ammonium.