Relative Strengths of Oxidizing and Reducing Agents
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Transcript of Relative Strengths of Oxidizing and Reducing Agents
Relative Strengths of Oxidizing and Reducing Agents
non-metals: gain electrons and are good oxidizing agents.
metals: lose electrons and are good reducing agents.
Brief Activity Series
Strong Reducing Agent.
Strong Oxidizing Agent
Li+(aq) + e- ↔ Li(s) Eo = -3.04 V (non-spontaneous as written)
Li+(aq) + e- → Li(s) Eo = -3.04 V (non-spontaneous)
Li+ is acting as a oxidizing agent (gaining an electron), but the negative sign shows this to be a non-spontaneous reaction.
Li(s) → Li+(aq) + e- Eo = +3.04 V (spontaneous)
Li(s) is acting as a reducing agent (losing an electron) and the positive sign shows this to be a spontaneous reaction.
So Li(s) makes a much better reducing agent than Li+(aq) makes as an
oxidizing agent.
Li+(aq) + e- ↔ Li(s) Eo = -3.04 V (non-spontaneous as written)
Li+(aq) + e- → Li(s) Eo = -3.04 V (non-spontaneous)
Li+ is acting as a oxidizing agent (gaining an electron), but the negative sign shows this to be a non-spontaneous reaction.
Li(s) → Li+(aq) + e- Eo = +3.04 V (spontaneous)
Li(s) is acting as a reducing agent (losing an electron) and the positive sign shows this to be a spontaneous reaction.
Zn2+(aq) + 2e- ↔ Zn(s) Eo = -0.76 V (non-spontaneous as written
Zn2+(aq) + 2e- → Zn(s) Eo = -0.76 V Zn2+ is acting as an oxidizing agent. Is it a stronger or weaker oxidizing agent than Li+? stronger,less
negative
Zn(s) → Zn2+(aq) + 2e- Eo = +0.76 V Zn(s) is acting as a reducing agent. Is it a stronger or weaker reducing agent than Li(s)?
Weaker, +3.04 > +0.76
Li(s) can reduce Zn2+(aq) or Zn2+(aq) can oxidize Li(s)
2Li(s) + Zn2+(aq) → 2Li+(aq) + Zn(s) Eocell= +3.04 + -0.76 = +2.28 V
What can be said about Mg(s) and Al3+(aq)?
What about Al3+(aq) and Zn2+(aq)?
Mg(s) can reduce Al3+(aq) or Al3+(aq) can oxidize Mg(s).
Nothing will happen, they are both fully oxidized.
Cr(s) can give electrons (reduce) any of the ions below it.
Cd2+ can (oxidize) gain electrons from the elements above.