|
|
|
|
Multiple Choice Questions on Corrosion Kinetics |
|
| Questions 1 - 5 |
Page 1 of 3 |
|
1. |
A low value of H2 over-voltage, in general, |
|
|
[ ] |
increases the rate of corrosion of steel in acids |
|
|
[ ] |
retards the rate of combination of hydrogen atoms into molecules |
|
|
[ ] |
decreases the rate of corrosion |
|
|
[ ] |
is caused by a good catalyst like mercury or lead |
|
|
2. |
The exchange current density (Io) for a cathodic reaction is determined |
|
|
[ ] |
by extrapolating from the Tafel region to the reversible potential Erev) |
|
|
[ ] |
by extrapolating from the Tafel region to the reversible potential Erev(a) |
|
|
[ ] |
by extrapolating from either the anodic or Tafel region to the corrosion potential, Ecorr |
|
| [ ] | from the corrosion potential determined experimentally | |
|
3. |
The absolute value of hydrogen over-voltage for a given metal decreases |
|
|
[ ] |
if the metal surface is polished |
|
|
[ ] |
if the temperature is lowered |
|
|
[ ] |
if a catalyst, like platinum, is added |
|
| [ ] | by increasing current density | |
|
4. |
Limiting current density is reached when |
|
|
[ ] |
the concentration at the electrode/electrolyte surface become larger than in the body of the solution |
|
|
[ ] |
the rate of reduction of species exceeds the rate of oxidation |
|
|
[ ] |
the concentration of ionic species at the metal/electrolytic surface reaches zero |
|
|
[ ] |
the concentration of ionic species at the metal/electrolyte surface is larger than in the bulk solution |
|
|
5. |
In the cathodically polarizing steel in an electrolyte |
|
|
[ ] |
the steel is connected to the positive terminal of the source of potential and the voltage is impressed in the positive direction |
|
|
[ ] |
the steel is made the counter-electrode in a polarization cell |
|
|
[ ] |
steel is connected to the negative terminal and the current is impressed in the negative direction |
|
|
[ ] |
steel is connected to the negative terminal and voltage applied in the noble direction |
|
|
|