Electrochemistry

Oxidation Loss of electrons to become more positive Tends to occur to metals 2Mg(s) + O2(g)  2MgO(s) 2Mg(s) + O2(g)  2Mg2+ + 2O2- Does not have to be in the presence of oxygen Mg(s) + Cl2(g)  MgCl2(s) Mg(s) + Cl2(g)  Mg2+ + 2Cl-

Reduction Gain of electrons to become more negative Tends to occur to nonmetals Mg(s) + Cl2(g)  MgCl2(s) Mg(s) + Cl2(g)  Mg2+ + 2Cl- Oxidation-reduction reactions (redox reactions) involve the transfer of electrons

Loss of Electrons Oxidation Gain of Electrons Reduction the lion says

Oxidation Is a Loss Reduction Is a Gain

Redox Half Reactions Redox reactions can be separated into two half-reactions to represent the oxidation and reduction separately Zn(s) + CuSO4(aq)  Cu(s) + ZnSO4(aq) Zn(s) + Cu2+(aq) + SO42-(aq)  Cu(s) + Zn2+(aq) + SO42-(aq) Oxidation: Zn(s)  Zn2+(aq) + 2e- Reduction: Cu2+(aq) + 2e-  Cu(s)

Practice Worksheet: Writing REDOX reactions p. 656 #7-11