EGEE 420 CORRECT FINALS ANSWERS AND
QUESTIONS SET A+
✔✔The rxn Zn + CuSO4 -> Cu + ZnSO4 takes place in_____ - ✔✔a galvanic cell
✔✔What's the equation for power (P)? - ✔✔P = i E
✔✔Calculate the mass of copper dissolved during electrolysis in Daniell cell if teh
charge passed through the electrode is 30.62C - ✔✔0.0101G
✔✔The expression for the Faraday's law of electrolysis is____. - ✔✔m = v.i M.i Q / (F v)
m = v.i M.i t i / (F v)
✔✔Three reasons for polishing the metal electrodes with sand paper before performing
electrochemical measurements are to______. - ✔✔>avoid an undesirable reaction
>remove the impurities
>remove the metal oxide layer
✔✔What are the experimental procedures for the open circuite potential measurement?
- ✔✔1. polish electrodes
2. weigh electrodes
3. connect electrochemical cell and electrometer
4. assemble the cell
✔✔How to deal with the waste solutions after the Daniell Cell? - ✔✔should be collected
in containers
✔✔What's the purpose of using a DC power supply in the Daniell Cell? - ✔✔To provide
electrical power
✔✔The exchange current density is defined when there is:
-zero overpotential
-no net current at an electrode - ✔✔both of these
, ✔✔In the rxn profile, the activated complex is located at:
-b/t potential energy min and max
-the pot. energy min
-the pot. energy max - ✔✔The potential energy maximum
✔✔The net current density is defined as: - ✔✔anodic - cathodic
✔✔If transfer coefficient is approaching 1, the barrier topmost is______. - ✔✔shifted to
the left
✔✔When the exchange current density is 10^-1 A/cm2 the electrochemical reaction
is___________. - ✔✔electrochemically reversible
✔✔The two main contributors to an electrochemical reaction are___________. -
✔✔electron (charge) transfer and mass transfer
✔✔the charge transfer kinetics of a half-reaction is based on_____. - ✔✔transition state
theory & chemical kinetics
✔✔If the exchange current density is 10^-7 A/cm2 the electrochemical reaction is_____.
- ✔✔slow
✔✔Using B-V equation, calculate the current density for hydrogen half-rxn at 25C and
overpotential of 30mV if the exchange current density (jo) is 0.002 A/cm2 and transfer
coeff (alpha) is 0.5. - ✔✔0.00247 A/cm2
✔✔In three electrode electrochemical cell, the current flows between________. - ✔✔the
working and counter electrodes
✔✔If transfer coefficient is 0.5, the energy barrier is______. - ✔✔exactly symmetrical
✔✔A Tafel plot can be used to experimentally estimate:
-transfer coeff only
-the exchange current density only - ✔✔bot
✔✔Base on generalized B-V equation, we can conclude that when the anodic current
approaches it limiting value the overpotential goes to_________. - ✔✔(+) infinity
✔✔Current density is proportional to:
-the reaction rate
-the concentration
-both - ✔✔both
QUESTIONS SET A+
✔✔The rxn Zn + CuSO4 -> Cu + ZnSO4 takes place in_____ - ✔✔a galvanic cell
✔✔What's the equation for power (P)? - ✔✔P = i E
✔✔Calculate the mass of copper dissolved during electrolysis in Daniell cell if teh
charge passed through the electrode is 30.62C - ✔✔0.0101G
✔✔The expression for the Faraday's law of electrolysis is____. - ✔✔m = v.i M.i Q / (F v)
m = v.i M.i t i / (F v)
✔✔Three reasons for polishing the metal electrodes with sand paper before performing
electrochemical measurements are to______. - ✔✔>avoid an undesirable reaction
>remove the impurities
>remove the metal oxide layer
✔✔What are the experimental procedures for the open circuite potential measurement?
- ✔✔1. polish electrodes
2. weigh electrodes
3. connect electrochemical cell and electrometer
4. assemble the cell
✔✔How to deal with the waste solutions after the Daniell Cell? - ✔✔should be collected
in containers
✔✔What's the purpose of using a DC power supply in the Daniell Cell? - ✔✔To provide
electrical power
✔✔The exchange current density is defined when there is:
-zero overpotential
-no net current at an electrode - ✔✔both of these
, ✔✔In the rxn profile, the activated complex is located at:
-b/t potential energy min and max
-the pot. energy min
-the pot. energy max - ✔✔The potential energy maximum
✔✔The net current density is defined as: - ✔✔anodic - cathodic
✔✔If transfer coefficient is approaching 1, the barrier topmost is______. - ✔✔shifted to
the left
✔✔When the exchange current density is 10^-1 A/cm2 the electrochemical reaction
is___________. - ✔✔electrochemically reversible
✔✔The two main contributors to an electrochemical reaction are___________. -
✔✔electron (charge) transfer and mass transfer
✔✔the charge transfer kinetics of a half-reaction is based on_____. - ✔✔transition state
theory & chemical kinetics
✔✔If the exchange current density is 10^-7 A/cm2 the electrochemical reaction is_____.
- ✔✔slow
✔✔Using B-V equation, calculate the current density for hydrogen half-rxn at 25C and
overpotential of 30mV if the exchange current density (jo) is 0.002 A/cm2 and transfer
coeff (alpha) is 0.5. - ✔✔0.00247 A/cm2
✔✔In three electrode electrochemical cell, the current flows between________. - ✔✔the
working and counter electrodes
✔✔If transfer coefficient is 0.5, the energy barrier is______. - ✔✔exactly symmetrical
✔✔A Tafel plot can be used to experimentally estimate:
-transfer coeff only
-the exchange current density only - ✔✔bot
✔✔Base on generalized B-V equation, we can conclude that when the anodic current
approaches it limiting value the overpotential goes to_________. - ✔✔(+) infinity
✔✔Current density is proportional to:
-the reaction rate
-the concentration
-both - ✔✔both
