EGEE 441 E4

In an electrolytic cell, the signs of the exchange current density (jo) and current density (j) are: [Note:see table 8.1 p168]

In a PEMFC, water is

If the total, voltage, and current efficiencies are, respectively, 40%, 50%, and 95%, the thermodynamic efficiency of an electrochemical energy conversion system (without heat exchange) is

Cation conductive membranes are used in [Note: DMFC is a type of PEMFC]

The metal dissolution half-reaction in a corrosion process is

If a hydrogen/oxygen generation [H2O(l) = H2(g) + 0.5 O2(g), E0 = -1.229V] electrolytic cell operates at 25 C under the following parameters for the potential-current density equation (AEC = 0.1V, BEC = 0.04 V, j0 = 0.001 A/cm^2, jp = 0.02 A/cm^2, jlim = -0.9 A/cm^2, rEC = 0.4 ohm cm^2), calculate the potential difference (cell voltage) when the electrolysis current density is (I) 0 A/cm^2 and (II) -0.2 A/cm^2.

The cathodic protection of Fe(s) against electrochemical corrosion, Fe(s) = Fe2 + 2 e-, can be provided using

Corrosion can not be decreased by

Immunity of Cu(s) at ambient conditions in an acidic solution at pH = 2 can be achieved at

Which of these fuel cells requires platinum as a catalyst?

What is the molar Gibbs energy of H2/O2 PEMFC reaction written as 2 H2(g) + O2(g) = 2 H2O(l), if the standard electrode potential difference is 1.2 V?

Using data from Chapter 10: Data Section, calculate the standard thermodynamic efficiency of a CO2/O2 electrolytic cell at 800 K [CO2(g) = C(s) + O2(g)].

When the entropy of an electrochemical reaction in a fuel or an electrolytic cell is negative, a part of the total available energy will be ____________ in the form of heat.

Corrosion resistance of a metal is considered poor if the corrosion rate is [Note; p181 Table 9.1]

If the corrosion current is 0.02 mA/cm^2, the corrosion rate of copper (M = 63.55 g/mol, p = 8.96 g/cm^3) due to Cu(s) -> Cu2+ (aq) + 2 e- reaction is _____. (Hint: 365.2 day/year)

In an fuel cell, the signs of the limiting current density and parasitic current density are

As temperature increases in a fuel cell, the charge transfer resistance

If the current density in a corrosion process 0.05 A/cm^2 and the overpotential is 200 mV, the area specific corrosion polarization resistance is [Note:eq9.4 pg179]

For the corrosion process with two-electron half-reactions at 25 C, if the overpotential from Ecorr is 10 mV and the measured current density response is 5 mA/cm^2, with the anodic and cathodic symmetry coefficients, respectively, 0.75 and 0.25, the corrosion current density, jcorr using the Stern Geary equation is [Note: p179-180]

Corrosion of Al(s) in aerated water is likely to take place at [Note: p177 Fig. 9.2]

The fuel cell was invented by

The fuel cell was discovered in

Aqueous KOH solution is used as electrolyte in

DMFC is a kind of

An anion conductive membrane is used in

In DMFC water is

Carbon monoxide can be used as a fuel in

At ambient temperature and pressure, for the PEMFC cathode, the main challenge to be addressed is the

At ambient pressure and temperature above 100 °C, for the PEMFC cathode, the main challenge to be addressed is the

In PEMFC, the electrolyte is

Using data from Chapter 10: Data Section, estimate the standard value of the Gibbs energy of an H2/O2 PEMFC [H2(g) + (1/2) O2(g) = H2O(g)] at 1000 K.

Using data from Chapter 10: Data Section, calculate the standard value of the decomposition potential (DP) of the H2O electrolysis [H2O(l) = H2(g) + (1/2) O2(g)] at 100 °C.

Using data from Chapter 10: Data Section, the standard thermodynamic efficiency of a C/O2 fuel cell [C(s) + O2(g) = CO2(g)] at 900 K is

Using data from Chapter 10: Data Sections, calculate the voltage efficiency of a C/O2 fuel cell [C(s) + O2(g) = CO2(g)] at 1000 K when the fuel cell potential is 0.5 V and all activities equal 1.

If the thermodynamic, voltage, and current efficiencies are, respectively, 93, 51, and 95 %, the total efficiency of an electrochemical energy conversion system (without heat exchange) I

Using the following parameters of the potential-current density equation (AFC = 0.08 V, BFC = 0.05 V, jo = 0.001 A/cm2, jp = 0.01 A/cm2 , jlim = 1.0 A/cm2, rFC = 0.2 Ω cm2) for a H2/O2 PEMFC, [H2(g) + (1/2) O2(g) = H2O(l), 25 °C] calculate the cell potential, EFC, at (I) 0 A/cm2 and (II) 0.7 A/cm2 with all species at unit activity.

The fuel cell was developed by

In a water electrolyzer at ambient conditions and at low current, the heat is

In a H2/O2 fuel cell at ambient conditions and at low current, the amount of heat released due to electrochemical reactions is about

Using data from Chapter 10: Data Section, calculate the standard thermodynamic efficiency of a water electrolyzer at ambient conditions.

The Flade potential is due to metal

The electrochemical corrosion involves

In an electrochemical corrosion process, the current of the anodic and cathodic reactions should be

In an electrochemical corrosion measurement

To correctly study a metal corrosion rates, the electrochemical cell should have

The current density in the passive region of a corrosion polarization curve is

If the corrosion current is 0.1 mA/cm2, the corrosion rate of iron due to Fe(s) → Fe2+(aq) + 2 e- reaction is

The potential-pH (Pourbaix) diagram can

Immunity of Al(s) at ambient conditions in pure water can be achieved at Eh

In the Cu(s) Pourbaix diagram, the line corresponding to Cu2+(aq) + 2 H2O(l) = Cu(OH)2(s) + 2 H+(aq) reaction is

In the Cu(s) Pourbaix diagram, the line corresponding to Cu2+(aq) + 2 e– = Cu(s) half-reaction is

In the Cu(s) Pourbaix diagram, the line corresponding to Cu2O(s) + 2 H+(aq) + 2 e- = 2 Cu(s) + H2O(l) half-reaction is

When pH = 0 and temperature is 25 °C, the oxygen reduction line [2 H+(aq) + (1/2) O2(g) + 2 e- = H2O(l)] in the Pourbaix diagram intersects the Eh axis at

When pH = 7 and temperature is 25 °C, the hydrogen evolution line [2 H+(aq) + 2 e- = H2(g)] in the Pourbaix diagram intersects the Eh axis at

Mitigation of corrosion can be provided by

If Zn(s) and Fe(s) are galvanically coupled, the metal to be corroded is Chapter 9: Electrochemical Corrosion & Chapter 4: Equilibrium Electrochemistry

The cathodic protection of Cu(s) can be provided, if Cu(s) is galvanically connected to

In any Pourbaix diagram, a line can represent

To calculate the corrosion current,

Transpassivation occurs due to