Instrumental test 4

• Electrochemistry- Electros and Electropotentials
• Redox reaction- e^- are transferred from one species to another
• Redox- Reduction and oxidation
• Reduced- gains electrons
• Oxidized- loses electrons
• Oxidizing agent-Takes the electron and becomes reduced (e acceptor)
• Reducing agent- gives electron and becomes oxidized (e donor)
• e- 1.602x10^-19 Coulombs
• Current- Flow of electrons per second e/s
• J=VxC (Joules = Volts x Current)
• Galvonic cell- a spontaneous reaction that generates electricity
• Salt Bridge- Isolates the reactants but keeps electrical contact between cells
• Electrical Potential- The work needed to move electrons from one point to another
• SHE- 0 volts
• K=10^nEcell/0.0592 (memorize this)
• Ecell= (+E)-(-E) (memorize this)
• Ion-selective electrode- a voltage difference is produced across a membrane due to difference in concentration of a select ion inside + outside of thte electrode
• Soda glass- Thin glass electrode with sodium
• Electrogravimetric Analysis- Analyte is plated out on an electrode + weighed
• 2 ways to check if its done- When all color is gone and Leave some of the electrode out of the solution, then when you think it is done put some of the electrode back into the solution + see if it changes
• Voltommetry- A group of electrochemical methods in which information about the analyze is derived from the measurement of current as a function of applied potential obtained under conditions that encourages polarization of an indicator (working electrode)
• Good things about Voltommetry: uses small electrode, uses small analyte
• Solution- contains analyte + supporting electrolyte
• Supporting electrolyte- an excess of nonreactive electrolyte
• Working electrode- a micro electrode whose potential is varied linearly with time
• Reference electrode- Has a known potential + is held constant
• Amalgon- mixture of two metals, mercury and another metal
• Auxiliary counter electrode- either a Pt wire or a pool of Hgthat conducts electricity fromth esource through the solution to the working electrode
• Hg micro electrodes (reasons to use them)- relatively large negative potential range, a fresh metallic surface is readily formed by a producing a new drop, many metal ions are reversibly reduced to amalgons at the surface of the Hg electrode
• Forward sweep (cathode sweep)-positive to negative potentials
• Reverse sweep (anodic sweep)- negative to positive potentials
• Cyclic Voltanagram- measured by current potential vs SCE
• Epc- peak potential cathode
• Epa- peak potential anode
• Ipa- Peak current of anode
• Ipc- peak current of cathode