Question

REDOX. Three Problems... need assistance. For the equations below, write the oxidation and reduction half reactions. In addition, Identify the substance oxidized, reduced, and agents for oxidation and reduction.

1. 2H2 + O2 > 2H2O

2. Fe + Zn2 > Fe2 + Zn

3. 2Al + 3Fe2 > 2Al3 + 3Fe

Answer 1

I'll do the first one for you as an example,

First assign oxidation states to all the atoms

\(\Large 2\underbrace{H_2}_0 + \underbrace{O_2}_0 \rightarrow 2\underbrace{H_2}_{+1}\underbrace{O}_{-2}\)

Overall there was a transfer of 4 electrons.

Hydrogen was oxidized because it went from 0 to +1 (4 atoms lost 1 electron each)

half-reaction: \(H_2\rightarrow 4~H^++4e^-\)

Since it was oxidized, \(H_2\) is the reducing agent.

Oxygen was reduced because it went from 0 to -2 (2 atoms gained 2 electrons each)

half-reaction: \(O_2 + 4e^-\rightarrow 2~O^{2-}\)

Since it was reduced, \(O_2\) is the oxidizing agent.