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Electrochemistry. Understand Redox reactions involve a transfer of electrons. Develop a metals activity series experimentally. Predict spontaneous reactions using an activity series. Burning and corrosion needs oxygen – oxidation.
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Understand Redox reactions involve a transfer of • electrons. • Develop a metals activity series experimentally. • Predict spontaneous reactions using an activity • series.
Burning and corrosion needs oxygen – oxidation. Oxidation-reduction reactions – (redox) Chemical changes when electrons are transferred from one reactant to another. Oxidation - an atom loses one or more electrons. Reduction- an atom gains one or more electrons. "LEO says GER” Losing Electrons is Oxidation, Gaining Electrons is Reduction
2 Ag+(aq) + Cu(s) ?? Atoms fight for electrons. The strongesttakes electrons from other substance. Strongest is reduced (gains), weakest is oxidized (loses). Metals do not gain electrons and are always oxidized.
2 Mg (s) + O2 (g) → 2 MgO (s) Mg – neutral Mg2+ ion O – neutral O2– ion Magnesium is . Oxygen is reduced. O + 2e- → O2- Mg → Mg2+ + 2e- These are called “half-reactions.”
Half-reactions show the oxidation or reduction reaction separated. +1 +2 0 0 Cu(s) + 2 AgNO3(aq) → Cu(NO3)2(aq) + 2 Ag(s) Oxidation: Cu → Cu2+ + 2e– Reduction: Ag+ + 1e– → Ag Half reactions are often shown as aqueous net ionic equations – spectator IONS not included.
Spontaneous rxns occurs without added energy. 2 Ag+(aq) + Cu(s) → Ag(s) + Cu2+(aq) → 2 Ag(s) + Cu2+(aq) no reaction Ag+ions can oxidizeCu metal. Cu2+cannot oxidize Ag metal. Cu metal can reduce Ag+ ions. Ag metal cannot reduce Cu2+ ions.
