Question

Consider a hydrogen-oxygen fuel cell, an electrochemical cell that generates electricity from the chemical reaction 2...

Consider a hydrogen-oxygen fuel cell, an electrochemical cell that generates electricity from the chemical reaction

2 H2(g) + O2(g) → 2 H2O(l) .
Yes, this is the same reaction as in additional question 1, but now we are looking at electrochemical aspects of it. On one side of the cell, H2 is pumped in, and the half-cell reaction is

2 H2(g) + 4 OH(aq) → 4 H2O(l) + 4 e– ; at the other side, O2 is pumped in:

O2(g) + 2 H2O(l) + 4 e- → 4 OH(aq) .

a) Which half-cell is oxidation? Which is reduction?

b) Compute the standard cell potential, E°, from the standard half cell potentials given in your textbook.

c) Suppose the cell operates at room temperature (25°C) and with H2 partial pressure of 0.10 bar and O2 partial pressure 0.20 bar. Use the Nernst equation to compute the cell potential under these conditions.

Homework Answers

Answer #1

2 H2(g) + 4 OH(aq) → 4 H2O(l) + 4 e– oxidation half reaction

O2(g) + 2 H2O(l) + 4 e- → 4 OH(aq) . reduction half reaction

b.2 H2(g) + 4 OH(aq) → 4 H2O(l) + 4 e–      E0 = 0.83v

O2(g) + 2 H2O(l) + 4 e- → 4 OH(aq) .       E0 = 0.4v

------------------------------------------------------------------------

2 H2(g) + O2(g)----------------------> 2 H2O(l) E0 cell = 1.23v

c.

n = 4

Ecell   = E0 cell - 0.0592/n logQ

           = 1.23- 0.0592/4 log1/P2H2 PO2

        = 1.23- 0.0592/4 log1/(0.1)^2*0.2

      = 1.23- 0.0148*-2.6989    = 1.2699v >>>>answer

Know the answer?
Your Answer:

Post as a guest

Your Name:

What's your source?

Earn Coins

Coins can be redeemed for fabulous gifts.

Not the answer you're looking for?
Ask your own homework help question
Similar Questions
Consider an electrochemical cell based on the following reaction: Zn(s) + 2H2O(l) + 2OH-(aq) ⇄ [Zn(OH)4]2-(aq)...
Consider an electrochemical cell based on the following reaction: Zn(s) + 2H2O(l) + 2OH-(aq) ⇄ [Zn(OH)4]2-(aq) + H2(g) All dissolved species are at 2.5 x 10-3 M; pressure of H2 is 1 bar (standard state) Use the Nernst equation to calculate E.
An aqueous ScF3 solution is electrolyzed under 1 bar pressure using platinum electrodes. (a) Write the...
An aqueous ScF3 solution is electrolyzed under 1 bar pressure using platinum electrodes. (a) Write the half-reactions predicted to occur at the anode and cathode, based on the standard cell potentials given below. Standard Reduction Potentials (Volts) at 25 °C F2(g) + 2 e- ---------> 2 F-(aq) 2.870 O2(g) + 4 H3O+(aq) + 4 e- --------> 6 H2O(l) 1.229 2 H2O(l) + 2 e- -------> H2(g) + 2 OH-(aq) -0.828 Sc3+(aq) + 3 e- ---------> Sc(s) -2.080 Half-reaction at anode:...
3. Consider a Ni2+ solution. How much NI deposits on the cathode if a current of...
3. Consider a Ni2+ solution. How much NI deposits on the cathode if a current of 0.150A is applied for 12.2 minutes? 4. Consider an electrochemical cell based on the following reaction: Zn(s) + 2H2O(l) + 2OH-(aq) ⇄ [Zn(OH)4]2-(aq) + H2(g) All dissolved species are at 2.5 x 10-3 M; pressure of H2 is 1 bar (standard state) Use the Nernst equation to calculate E.
What is the calculated value of the cell potential at 298 K for an electrochemical cell...
What is the calculated value of the cell potential at 298 K for an electrochemical cell with the following reaction, when the H2 pressure is 5.00×10-3 bar, the H+ concentration is 1.46 M, and the Zn2+concentration is 3.42×10-4 M ? 2H+(aq) + Zn(s) ----> H2(g) + Zn2+(aq) Answer: _____ V ? The cell reaction as written above is product-favored (spontaneous) for the concentrations given: _______(true/false)?
Answer the following questions related to the given electrochemical cell. IO−(aq) + H2O(l) + 2e− ⇌...
Answer the following questions related to the given electrochemical cell. IO−(aq) + H2O(l) + 2e− ⇌ I−(aq) + 2OH−(aq) E° = 0.485 V 2NO(g) + H2O(l) + 2e− ⇌ N2O(g) + 2OH−(aq) E° = 0.760 V 3. The other cell compartment is comprised of a Pt electrode in a solution containing NO(g) at a pressure of 0.543 atm and N2O(g) at a pressure of 0.345 atm at a temperature of 353.7 K. The concentration of OH− is 8.67 × 10-1...
A) What is the calculated value of the cell potential at 298K for an electrochemical cell...
A) What is the calculated value of the cell potential at 298K for an electrochemical cell with the following reaction, when the Cl2 pressure is 8.15×10-4 atm, the Cl- concentration is 1.48M, and the Pb2+ concentration is 1.07M ? Cl2(g) + Pb(s) ---> 2Cl-(aq) + Pb2+(aq) Answer: _____ V The cell reaction as written above is spontaneous for the concentrations given:____ ( TRUE/FALSE ) B)What is the calculated value of the cell potential at 298K for an electrochemical cell with...
What is the OCP (open circuit potential) of the H2(g)/Cl2(g) electrochemical cell [Pt(s)|H2(g)|HCl(aq)|Cl2(g)|Pt(s)] at 25 oC,...
What is the OCP (open circuit potential) of the H2(g)/Cl2(g) electrochemical cell [Pt(s)|H2(g)|HCl(aq)|Cl2(g)|Pt(s)] at 25 oC, if partial pressure of hydrogen and chlorine are 0.5 bar and the concentration of HCl(aq) is 5 mol/kg?
What is the standard cell potential for an electrochemical cell based on the following half-reactions? IO3-(aq)...
What is the standard cell potential for an electrochemical cell based on the following half-reactions? IO3-(aq) + 6 H+(aq) + 6 e- ----> I-(aq) + 3 H2O(l ) E° = 1.085 V Zn2+(aq) + 2 e- ---> Zn(s) E° = -0.762 V
Shown below are the reactions occurring in the direct methanol fuel cell (DMFC). I 2 CH3OH(aq)...
Shown below are the reactions occurring in the direct methanol fuel cell (DMFC). I 2 CH3OH(aq) + 2 H2O(l) → 2 CO2(g) +12 H+(aq) +12 e- II 3 O2(g) + 12 H+(aq) + 12 e- → 6 H2O(l) Overall 2 CH3OH(aq) + 3 O2(g) → 2 CO2(g) + 4 H2O(l) Which is the anode reaction, and what is being oxidized in the overall reaction? II, O2 I, H2O II, H+ IV, CH3OH
Standard Reduction (Electrode) Potentials at 25 oC Half-Cell Reaction Eo (volts) Standard Reduction (Electrode) Potentials at...
Standard Reduction (Electrode) Potentials at 25 oC Half-Cell Reaction Eo (volts) Standard Reduction (Electrode) Potentials at 25 oC Half-Cell Reaction Eo (volts) F2(g) + 2 e- 2 F-(aq) 2.87 Ce4+(aq) + e- Ce3+(aq) 1.61 MnO4-(aq) + 8 H+(aq) + 5 e- Mn2+(aq) + 4 H2O(l) 1.51 Cl2(g) + 2 e- 2 Cl-(aq) 1.36 Cr2O72-(aq) + 14 H+(aq) + 6 e- 2 Cr3+(aq) + 7 H2O(l) 1.33 O2(g) + 4 H+(aq) + 4 e- 2 H2O(l) 1.229 Br2(l) + 2 e-...
ADVERTISEMENT
Need Online Homework Help?

Get Answers For Free
Most questions answered within 1 hours.

Ask a Question
ADVERTISEMENT