Question

Compare the theoretical stoichiometric reaction from (Wiedemeier):

• 1 mg of dissolved oxygen can be used by microbes to degrade 0.32 mg of BTEX

to the results you found from empirical observation:

Results from the stoichiometric problems showed that it requires: • 3.1 g of O2 to biodegrade 1 gram of Benzene CH6+7.502 +6CO2 + 3H20 2.5 g of O2 to biodegrade 1 gram of Toluene CH3 +902 7CO2 + 4H20 3.2 g of O2 to biodegrade 1 gram of Ethylbenzene (and isomer xylene) C8H10 + 10.502 8CO2 + 5H20

Compare the results from actual vs theoretical.

Answer 1

1). C6H6 + 7.5 O2 ---> 6 CO2 + 3 H2O

So, this means theoretically 1 mol C6H6 reacts with 7.5 mol O2 to produce 6 mol CO2 and 3 mol H2O.

M.W. of C6H6 = 78 g/mol

1g benzene = 1/78 mol.

Theoretical O2 required = 1/78 × 7.5 mol = 0.11538 mol

M.W. of O2 =32 g/mol

Theoretical O2 required = 0.11538 mol × 32 g/mol = 3.692 g while actual given is 2.5 g.

2). C7H8 + 9 O2 ----> 7 CO2 + 4 H2O

M.W. of C7H8 = 92 g/mol

In 1 g C7H8, no. of moles = 1/92 mol

Theoretical O2 required = 9 × 1/92 mol = 9/92 mol × 32 g/mol = 3.13 g while actual given is 2.5 g.

3). C8H10 + 10.5 O2 ----> 8 CO2 + 5 H2O

M.W. of C8H10 = 106 g/mol

1 g C8H10 = 1/106 mol

Theoretical O2 required = 10.5 × 1/106 mol = 10.5/106 mol = 32 g/mol × 10.5/106 mol = 3.17 g while actual given is 3.2 g.