Question

use the half reaction method to balance (SHOW ALL WORK) the following overall redox reaction describing the formation of acid mine drainage emanating from coal mines

FeS2(s)+o2(g)+H2o(l)->FE(OH)3(s) +SO4 2-(aq) +H+(aq)

balance redox entirely

1)FeS2+o2+h2o->fe2+ +So4 2- +h+

Balance redox entirely

2)2Fe2+ . + 1/2 O2 + 2H+ . ->2Fe3+ +H20

Balance this precipitation reaction

Fe3+(aq) +3H2o(l) . -> F(OH)3 (s) +3H+(aq)

Answer 1

Answer 2

To balance the given redox reaction, we'll follow the half-reaction method. We'll first balance the oxidation half-reaction and then the reduction half-reaction, making sure that the number of electrons transferred is the same in both reactions.

Step 1: Write the unbalanced oxidation and reduction half-reactions.

Oxidation half-reaction: FeS2(s) -> Fe^2+(aq) + SO4^2-(aq)

Reduction half-reaction: O2(g) + 4H2O(l) + 4e^- -> 4OH^-(aq)

Step 2: Balance the atoms in each half-reaction, excluding oxygen and hydrogen.

Oxidation half-reaction (Fe): FeS2(s) -> Fe^2+(aq) + SO4^2-(aq)

Reduction half-reaction (O): O2(g) + 2H2O(l) + 4e^- -> 4OH^-(aq)

Step 3: Balance oxygen atoms by adding H2O to the side that needs oxygen.

Oxidation half-reaction (Fe): FeS2(s) -> Fe^2+(aq) + SO4^2-(aq)

Reduction half-reaction (O): O2(g) + 4H2O(l) + 4e^- -> 4OH^-(aq)

Step 4: Balance hydrogen atoms by adding H^+ to the side that needs hydrogen.

Oxidation half-reaction (Fe): FeS2(s) -> Fe^2+(aq) + SO4^2-(aq)

Reduction half-reaction (O): O2(g) + 4H2O(l) + 4e^- -> 4OH^-(aq) + 4H^+(aq)

Step 5: Balance the charge by adding electrons to the side that needs them.

Oxidation half-reaction (Fe): FeS2(s) -> Fe^2+(aq) + SO4^2-(aq) + 4e^-

Reduction half-reaction (O): O2(g) + 4H2O(l) + 4e^- -> 4OH^-(aq) + 4H^+(aq)

Step 6: Now, equalize the number of electrons transferred in both half-reactions.

To do this, we need to multiply the oxidation half-reaction by 4 and the reduction half-reaction by 1.

Balanced oxidation half-reaction: 4FeS2(s) -> 4Fe^2+(aq) + 4SO4^2-(aq) + 16e^-

Balanced reduction half-reaction: O2(g) + 4H2O(l) + 4e^- -> 4OH^-(aq) + 4H^+(aq)

Step 7: Add the two balanced half-reactions together.

4FeS2(s) + O2(g) + 4H2O(l) -> 4Fe^2+(aq) + 4SO4^2-(aq) + 4OH^-(aq) + 4H^+(aq)

Finally, the balanced overall redox reaction is: 4FeS2(s) + O2(g) + 4H2O(l) -> 4Fe^2+(aq) + 4SO4^2-(aq) + 4OH^-(aq) + 4H^+(aq)