One measure of the organic content of wateris chemical oxygen demand (COD). In the COD test, organic matter is oxidized with dichromate, Cr2O72-, at low pH to CO2and the dichromate is reduced to Cr 3.Write the balanced overall reaction for the oxidation of ethanol (CH3CH2OH) in the COD test.

answer : (a) volume of the gas = 8.67 ×   l

                (b) second virial coefficient b = -1.21226 l/mole

solution :   given,     t = 300k

                                p = 20atm

                                z = 0.86

                                n = 8.2 mmoles = 8.2 × moles

                                r =   0.082 l atm/k/mol

        find,     (a) volume of gas   and (b) second virial coefficient b at 300k.

formula used :            

                          and            

(a)            

                    = \times 0.082\times 300}{20}[/tex]

                    = 8.67 ×   l

(b)      

                    = (0.00867-1) × 8.659

                    = - 8.5839 l/mole

it's 3.2 on edge, i just took the test.