1ElectrochemistryTwo major electrochemical types:Voltaic (galvanic) cells: Voltaic (galvanic) cells: Voltaic (galvanic) cells: Voltaic (galvanic) cells: Using spontaneous chemical reactions to do work (i.e. provide electricity).Electrolytic Cells: Electrolytic Cells: Electrolytic Cells: Electrolytic Cells: Using electricity to force nonspontaneousreactions.Purification of MetalsElectroplatingElectrochemistry is also tied to Gibbs Free Energy and Chemical EquilibriumOxidation-Reduction: The Heart of ElectrochemistryGeneral Idea:Since redox reactions involve the transfer of electrons from one component of a reaction to another, intercepting that transfer (flow) of electrons, allows useful “work” to be done (i.e. electrical circuits can be powered).Don’t Forget: Leo Goes GerLoses Electrons OxidizedGains Electrons ReducedExpanded Definition of Redox ReactionsOxidation:Oxidation:Oxidation:Oxidation:-Lose electrons-Gain oxygen (special case)-Lose hydrogen (special case)Reduction:Reduction:Reduction:Reduction:-Gain electrons-Lose oxygen (special case)-Gain hydrogen (special case)Ex.Ex.Ex.Ex. Cu(s)+ 2AgNO3(aq)→Cu(NO3)2(aq)+ 2Ag(s)In this example copper loses two electrons and each silver atom gains an electronCu0→Cu2++ 2e-and is considered oxidizedThis is the oxidation half-reaction. It only shows the component oxidized and does not include any spectator ions.2Ag++ 2e-→2Ag and is considered reducedThis is the reduction half-reaction. It only shows the component reduced and does not include any spectator ions.Net Ionic: Cu(s)+ 2Ag+(aq)→Cu2+(aq)+ 2Ag(s)Characteristics:-Electrons are lost/gained by particles in the reaction-There must be a change in “oxidation number”.-You must know the rules for assigning oxidation numbers-Oxidation numbers are for “book keeping purposes” and may not represent actual charges-Oxidations and reductions must occur in pairs (i.e. electron loss must be accompanied by electron gain)-The oxidizing “agent” does the oxidizing and is itself reduced (agent refers to entire species)-The reducing “agent” does the reducing and is itself oxidized.-In a disproportionation reaction, an element in one oxidation state is simultaneously oxidized and reduced.