Galvanic Cell
AP* Chemistry ELECTROCHEMISTRY
Terms to Know: Electrochemistry—the study of the interchange of chemical and electrical energy OIL RIG – oxidation is loss, reduction is gain (of electrons) Oxidation – the loss of electrons, increase in charge Reduction – the gain of electrons, reduction of charge Oxidation number – the assigned charge on an atom Oxidizing agent (OA) – the species that is reduced and thus causes oxidation Reducing agent (RA) – the species that is oxidized and thus causes reduction ELECTROCHEMISTRY INVOLVES TWO MAIN TYPES OF PROCESSES: A. Galvanic (voltaic) cells – which are spontaneous chemical reactions (battery) B. Electrolytic cells – which are non-spontaneous and require external e− source (DC power source) C. BOTH of these fit into the category entitled Electrochemical cells
GALVANIC CELLS
Parts of the voltaic or galvanic cell: o Anode--the electrode where oxidation occurs. After a period of time, the anode may appear to become smaller as it falls into solution. o Cathode-- the anode where reduction occurs. After a period of time it may appear larger, due to ions from solution plating onto it. o inert electrodes—used when a gas is involved OR ion to ion involved such as Fe3+ being reduced to Fe2+ rather than Fe0. Made of Pt or graphite. o Salt bridge -- a device used to maintain electrical neutrality in a galvanic cell. This may be filled with agar which contains a neutral salt or it may be replaced with a porous cup. o Electron flow -- always from anode to cathode. (through the wire) o Standard cell notation (line notation) - anode/solution// cathode solution/ cathode Ex. Zn/Zn2+ (1.0 M) // Cu2+ (1.0 M) / Cu o Voltmeter - measures the cell potential (emf) . Usually is measured in volts. Balance this re-dox reaction: MnO4- + Fe2+ → Mn2+ + Fe3+ RED: OA: OX: RA Overall rxn:
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*AP is a registered trademark of the College Board, which was not involved in the production of, and does not endorse, this product. © 2008 by René McCormick. All
Terms to Know: Electrochemistry—the study of the interchange of chemical and electrical energy OIL RIG – oxidation is loss, reduction is gain (of electrons) Oxidation – the loss of electrons, increase in charge Reduction – the gain of electrons, reduction of charge Oxidation number – the assigned charge on an atom Oxidizing agent (OA) – the species that is reduced and thus causes oxidation Reducing agent (RA) – the species that is oxidized and thus causes reduction ELECTROCHEMISTRY INVOLVES TWO MAIN TYPES OF PROCESSES: A. Galvanic (voltaic) cells – which are spontaneous chemical reactions (battery) B. Electrolytic cells – which are non-spontaneous and require external e− source (DC power source) C. BOTH of these fit into the category entitled Electrochemical cells
GALVANIC CELLS
Parts of the voltaic or galvanic cell: o Anode--the electrode where oxidation occurs. After a period of time, the anode may appear to become smaller as it falls into solution. o Cathode-- the anode where reduction occurs. After a period of time it may appear larger, due to ions from solution plating onto it. o inert electrodes—used when a gas is involved OR ion to ion involved such as Fe3+ being reduced to Fe2+ rather than Fe0. Made of Pt or graphite. o Salt bridge -- a device used to maintain electrical neutrality in a galvanic cell. This may be filled with agar which contains a neutral salt or it may be replaced with a porous cup. o Electron flow -- always from anode to cathode. (through the wire) o Standard cell notation (line notation) - anode/solution// cathode solution/ cathode Ex. Zn/Zn2+ (1.0 M) // Cu2+ (1.0 M) / Cu o Voltmeter - measures the cell potential (emf) . Usually is measured in volts. Balance this re-dox reaction: MnO4- + Fe2+ → Mn2+ + Fe3+ RED: OA: OX: RA Overall rxn:
[acidic]
*AP is a registered trademark of the College Board, which was not involved in the production of, and does not endorse, this product. © 2008 by René McCormick. All