Pyrite oxidation leads to acidic conditions due to A a slow

Pyrite oxidation leads to acidic conditions due to:

A. a slow chemical oxidation of FeS2

B.  a rapid chemical oxidation of FeS2

C. Bacterial oxidation of Fe++

D. All of these

Solution

Pyrite(FeS2) is a irion sulphide allso called fools gold found i n earth\'s crust especially in coals and mineral ores.

The various steps of pyrite oxidation is as follws

2 FeS₂ + 7 O₂ + 2 H₂O => 2 Fe²⁺ + 4 SO₄^2- + 4 H⁺
Pyrite + Oxygen + Water => Ferrous Iron + Sulfate + Acidity

4 Fe²⁺ + O₂ + 4 H⁺ => 4 Fe₃₊ + 2 H₂O
Ferrous Iron + Oxygen + Acidity => Ferric Iron + Water

4 Fe³⁺ + 12 H₂O => 4 Fe(OH)³ ¯ + 12 H⁺
Ferric Iron + Water => Ferric Hydroxide (yellowboy) + Acidity

FeS₂ + 14 Fe³⁺ + 8 H₂O => 15 Fe²⁺ + 2 SO₄^2- + 16 H⁺
Pyrite + Ferric Iron + Water => Ferrous Iron + Sulfate + Acidity

pyrite oxidation occurs at slow rate in rocks but some bacterias increases the rate of pyryte oxidation