Batteries Flashcards
Lead-acid battery reaction
Pb (s) + PbO2 (s) + 4H+ (aq) + 2 SO4(2-)(aq) –> 2PbSO4 (s) + 2H2O (l) (half-reactions on chart)
Lead-acid battery components + model
Solid grids alternating from each other in H2SO4 (aq) solution, cathode made of solid PbO2 and anode made of spongy lead Pb (s).
Lead-acid battery initial charging reaction
Overall: Pb(s) + 2H2O(l) –> PbO2(s) + 2H2(g)
(cathode reaction reduces H+ ions because Pb(s) cannot be reduced
Lead-acid battery initial components + model
Lead grids alternating each other (anode and cathode) in H2SO4 solution
Voltaic cells flow of electrons
Anode to cathode
Voltaic cells flow of ions
cations to cathode, anions to anode
Voltaic cell components + model
Anode (solid in anode solution), cathode (solid in cathode solution), salt bridge, wire connecting cathode and anode to voltmeter
Voltaic cell standard notation
|Anode|Anode solution||Cathode solution|Cathode
Standard Hydrogen Electrode (SHE) purpose
Used to determine the standard cell potential of different substances
SHE reaction + model
2H+(aq) + 2e- –> H2(g) (oxidation of H2 and reduction of H+ occur on surface of Pt electrode)
Alkaline battery reaction
Zn + 2MnO2 + 2H2O –> Zn(OH)2 + 2MnO(OH)
Zn is oxidized, Mn is reduced
Alkaline battery components + model
May contain several voltaic cells so not rechargeable
Circular in shape, contains cathode on top (MnO2 + graphite) and anode on bottom (Zn + KOH), gasket, separator, KOH is electrolyte
Nickel-cadmium batteries
rechargeable batteries, spontaneous reaction of reduction of nickel and oxidation of cadmium
Nickel-cadmium batteries reaction
2NiO(OH) + Cd + H2O –> 2Ni(OH)2 + Cd(OH)2
Lithium-ion batteries
Rechargeable
Spontaneous reduction of Co and oxidation of lithium
high voltage but flammable
Lithium-ion batteries reaction
Li (in graphite) + CoO2 –> graphite + LiCoO2
Fuel cells
Uses redox reactions between organic combustible fuels and O2 (g) to generate electricity
Voltaic cell, used in cars in H2/O2 fuel cells
Hydrogen fuel cell reaction + model
2H2 + O2 –> 2H2O
(H2 oxidized to H+ first, then reacts w O2 to form water)
Rust reaction
4Fe + 3O2 –> 2Fe2O3
Rust reaction components
Anode: Fe (reactive anode, is getting oxidized)
Cathode: Fe2O3 (self-reducing)
Rust reaction characteristics
Self-accelerating, sped up by presence of electrolytes like NaCl, slowed down by painting Fe or covering with sacrificial anodes
Electrolytic cell
Nonspontaneous reaction run by outside source (electrolysis), uses electricity to split up a molten substance (ex. NaCl)
Electrolytic cell sample reaction + model
NaCl (molten) –> Na (l) + 1/2Cl2 (g)