Unit 2 Exam Flashcards
Redox Reactions involve….
The transfer of electrons
Oxidation
Loss of electrons
Reduction
Gain of Electrons
Oxidizing Agent
Thing being reduced
Reducing Agent
Thing being oxidized
What are the two types of Cells. Give a brief description
Voltaic (Galvanic)- Spontaneous, system does work on surroundings Anode (-) -> Cathode (+)
Electrolytic- nonspontaneous, energy comes from surroundings Anode (+) -> Cathode (-)
Where does Oxidation occur?
Reduction?
Anode
Cathode
What does the salt bridge do?
Prevents the buildup of electrons at the cathode and a lack of electrons at the anode
Which has a higher reduction potential, the anode or the cathode?
Cathode
Voltage
Potential energy, potential for electrons to flow
Standard Hydrogen Electrode
Accepted Zero voltage
Not practical because of the release of H2 gas
Indicator Electrode
Where the analyte is active, most likely the Cathode
Reference electrode
Maintains a constant potential for relative voltage measurements by the indicator electrode
Anode
Examples of reference electrodes
Copper in lab
Ag/AgCl electrode
Hydrogen electrode
Combination electrode
Saturate Calomel Ectectrode (S.C.E)
Examples of indicator electrodes
Metal (wire, lead)
Ion selective (detecting only one ion)
How does a pH indicator work
PH of internal solution is fixed, as the pH of the external solution changes, the electron potential across the glass changes
How does an ion selective electrode work?
Unknown ion on outside, known on the inside, influx tells you the concentration
How is the voltage and the flow of electrons related?
The bigger the voltage the better the flow of electrons
Overpotential
Voltage required to overcome the activation energy for a reaction at an electrode surface
Ohmic Potential
Voltage needed to overcome the inherent cell resistance
Concentration Polarization
Occurs when the concentrations of reactants and products are different from those in bulk solution
How does adding ions (salt) effect the resistance
By adding salt, you are increasing the ions and decreasing the resistance because the ions are passing on the charge
