The orange material that coats the base of this stream is ferric hydroxide (Fe(OH)3). It is characteristic of streams in areas polluted by acid mine drainage where oxygen-rich water comes in contact with pyrite-rich (FeS2) coal. The reaction responsible for the creation of this iron compound is an example of which of the following? A. hydration
B. hydrolysis
C. oxidation
D. dissolution

C. oxidation

Explanation:

Acid mine drainage occurs when acidic water flows forth from metal or coal mine. The oxidation of pyrite is one of the major causes of acid mine drainage. Sulfide is oxidized to sulfate which undergoes solubilization to Iron(II). Iron(II) is further oxidized to Ferric Iron or Iron(III). The reaction proceeds this way;

4Fe²⁺₍aq₎  + O₂₍g₎  + 4H⁺₍aq₎  ⇒ 4Fe³₍aq₎ ⁺ 2H₂O₍l₎

Ferric hydroxide, also known as Yellow boy is obtained when the pH of the acid mine rises above three. This resultant outcome of the oxidization of pyrites is detrimental to aquatic life and humans if they should consume water containing the Yellow Boy.