EGEE 420 LATEST UPDATED ANSWERS AND QUESTIONS SET A.pdf

EGEE 420 LATEST UPDATED ANSWERS AND
QUESTIONS SET A+
✔✔Molecular hydrogen exists in
-very large quantities in nature
-significant quantities in nature
-small quantities in nature - ✔✔small quantities in nature

✔✔Commercialization of fuel cell technologies is mainly for
-portable, stationary and automotive power generation applications
-portable power generation applications only
-portable and stationary power generation applications only - ✔✔portable, stationary
and automotive power generation applications

✔✔Pt
-can form an s-block hydride
-can form a metallic hydride
-can not form a metallic hydride - ✔✔can not form a metallic hydride

✔✔A galvanic electrochemical cell produces
-electricity using chemicals
-chemicals using electricity
-either chemicals or electricity - ✔✔electricity using chemicals

✔✔Based on the IUPAC recommendation, the potential difference of the cell
Cu(s)|CuSO4(aq)||ZnSO4(aq)|Zn(s)|Cu(s) should be calculated as

E = EZn2+/Zn - ECu2+/Cu
E = ECu2+/Cu - ESHE
E = ECu2+/Cu - EZn2+/Zn - ✔✔E = EZn2+/Zn - ECu2+/Cu

✔✔Calculate the standard electrode potential difference (E°) of the Daniell cell (at 1 bar)
if temperature is 473.15 K.

,1.088 V
1.095 V
1.102 V - ✔✔1.088 V

✔✔What is the standard electrode potential of the Zn/Zn2+ electrode?

1.104 V
-0.762 V
0.342 V - ✔✔-0.762 V

✔✔In Nernst's equation the standard electrode potential depends
-on both of these
-on temperature
-on the concentration scales chosen for activities - ✔✔on both of these

✔✔In a galvanic cell, the electric potential
-of the cathode is more positive than the electric potential of the anode
-of the cathode is the same as the electric potential of the anode
-of the anode is more positive than the electric potential of the cathode - ✔✔of the
cathode is more positive than the electric potential of the anode

✔✔Using the CRC Handbook data, calculate the standard electrode potential of the O2
gas electrode at 1.014 bar and 100 oC.

1.167 V
1.229 V
0.998 V - ✔✔1.167 V

✔✔Using the CRC Handbook data, estimate the standard electrode potential (at 25 °C
and 1.013 bar) of the oxygen gas electrode.

1.229 V
2.020 V
0.695 V - ✔✔1.229 V

✔✔H2(g) = 2 H+(aq) + 2 e- is
-a reduction reaction
-an oxidation reaction
-a combustion reaction - ✔✔an oxidation reaction

✔✔A reduction process occurs at
-the cathode
-either the cathode or the anode

, -the anode - ✔✔the cathode

✔✔Using the CRC Handbook data, estimate the standard Gibbs energy, (ΔrG°) of
reaction of decomposition of liquid water to gaseous hydrogen and oxygen at 25 °C and
1 bar.

+237.141 kJ/mol
0 kJ/mol
-237.141 kJ/mol - ✔✔+237.141 kJ/mol

✔✔What is the electron number in an electrochemical reaction written as 2 H2(g) +
O2(g) = 2H2O(l)?

1
4
2 - ✔✔4

✔✔A Daniell cell consists of
-electrodes and electrolytes
-electrodes
-electrodes, electrolytes, and a salt bridge - ✔✔electrodes, electrolytes, and a salt
bridge

✔✔Activity of a solute in an aqueous solution is defined as
-activity coefficient times partial pressure
-activity coefficient times mole fraction
-activity coefficient times molality - ✔✔activity coefficient times molality

✔✔Calculate the standard electrode potential difference (E°) of the Daniell cell (at 25
°C) if pressure is 500 MPa.

1.102 V
1.099 V
1.080 V - ✔✔1.099 V

✔✔Oxidation is

-gathering of electrons in a half-reaction
-release of electrons in a half-reaction
-release of protons in a half-reaction - ✔✔release of electrons in a half-reaction

✔✔Using the CRC Handbook data, calculate the standard electrode potential difference
(E°) of a fuel cell, which consumes hydrogen and oxygen and produces gaseous water
at 1000 K and 1 bar.