Question

How much of the following chemicals would be required to remediate one kilogram of dichloromethane CH₂Cl₂)? (do not consider chemical impurities, soil porosity, or a safety factor here)

i) sodium permanganate (NaMnO₄) for chemical oxidation. (assume complete oxidation to co₂ and cl-)

Answer 1

We would need approximately 20.6 kg of sodium permanganate (NaMnO₄) to completely oxidize 1 kg of dichloromethane (CH₂Cl₂) to CO₂ and Cl⁻.

The complete oxidation of CH₂Cl₂ with NaMnO₄ can be represented as:

2CH₂Cl₂ + 7O₂ + 16MnO₄⁻ → 4CO₂ + 4Cl⁻ + 16MnO₂ + 8H₂O

The number of moles of CH₂Cl₂ is:

n(CH₂Cl₂) = (1 kg) / (85.5 g/mol)

= 11.7 mol

We determine the stoichiometric ratio of NaMnO₄ to CH₂Cl₂ and from the balanced equation, 16 moles of NaMnO₄ are required per 2 moles of CH₂Cl₂.

The number of moles of NaMnO₄ needed for 11.7 moles of CH₂Cl₂ is:

n(NaMnO₄) = (11.7 mol CH₂Cl₂) * (16 mol NaMnO₄ / 2 mol CH₂Cl₂)

= 93.6 mol

We finally convert moles of NaMnO₄ to grams

m(NaMnO₄) = n(NaMnO₄) * M(NaMnO₄)

= 93.6 mol * 219 g/mol

= 20604.4 g