Are My Electrochemistry Homework Answers Correct?

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SUMMARY

This discussion focuses on verifying answers related to electrochemistry homework, specifically balancing reactions, calculating cell voltages, and determining equilibrium constants. The user presents multiple questions, including balancing a reaction in acidic solution, calculating the cell voltage for a voltaic cell, and determining the oxidation state of a metal in an electrolytic cell. Key conclusions include the balanced reaction for the first question and the calculated cell voltage of 3.18V for the voltaic cell. The user seeks confirmation and guidance on their calculations and concepts.

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  • Understanding of redox reactions and balancing chemical equations
  • Familiarity with electrochemical cells and standard electrode potentials
  • Knowledge of Gibbs free energy and its relation to cell voltage
  • Basic principles of electrolytic processes and Faraday's laws
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  • Review the Nernst equation and its application in calculating cell voltage
  • Study the relationship between Gibbs free energy and equilibrium constants
  • Learn about the construction and labeling of voltaic cells
  • Explore the concept of molar concentration effects on cell potential
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Students studying electrochemistry, educators teaching chemical reactions, and anyone preparing for exams in physical chemistry or related fields.

mikesown
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This is a multi-question homework which I want to see if I understand fully. I have attempted as much as I can of it, and would appreciate it if members here could tell me if my answers are correct and if not could guide me in the direction. Thanks in advance.

1. Balance the following reaction that occurs in acidic solution
Question: S^{-2} + NO_{3}^{-1} -> NO_{2} + S_{8}
Answer(correct?): 32H^{+} + 16NO_{3}^{-} + 8S^{-2} -> S_{8} + 16NO_{2} + 16H_{2}O

2.
Mg^{+2} + 2e^{-} -> Mg E cell = -2.38V
Ag^{+1} + 1e^{-} -> Ag E cell = 0.80V
a. Write the oxidation half reduction, reduction half reduction, and the net reaction and calculate E cell.
Answer(correct?):
Oxidation: Mg -> Mg^{+2} + 2e^{-} 2.38V
Reduction: Ag^{+1} + 1e^{-} -> Mg .80V
Net: Mg+2Ag^{+1} -> Mg^{+2} + 2Ag 3.18V
b. Sketch the above voltiac cell and label the anode, cathode, and salt bridge. Write the formulas of two approciriate electrolytes. Label which electrode gains mass and which one looses mass.

(my best attempt at an ASCII rendition of the drawing)
Salt bridge
|
/------------------\
| |
| | | |
| | | |
| | | |
| | | |
____ ______
#1 #2

Mg in beaker#1(solution), anode, not sure about electrolyte!, Ag+1 in beaker #2, cathode, not sure about electrolyte. Second beaker electrolyte gains mass(because it's being reduced). First beaker looses mass. Not sure about electrolyte for salt bridge.

c) Determine the free energy value for the above Voltaic cell:
-6.14*10^(5) J

d) Find the numerical value of the equilibrium constant
2.71*10^(107) (Is this right? Seems large!)

e) Calculate the cell voltage if the SIlver electrolyte molarity changes to .10M while the magnesium electrolyte molarity is changed to .002M.
Didn't really know. Set up the following:
E cell = E(degree) cell * .0592/2 * log Q

3. A current of 10.0 amperes flows for 2.00 hours through an electrolytic cell containing a molten salt of metal X. The result is the decomposition of .250 moles of metal X at the cathode. The oxidation state of X in the molten state is?

I found the number of mol e-, which was 7.46*10^(-1), but I didn't know where to go from here.

Any help would be _greatly_ appriciated!

Thanks!
 
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mikesown said:
3. A current of 10.0 amperes flows for 2.00 hours through an electrolytic cell containing a molten salt of metal X. The result is the decomposition of .250 moles of metal X at the cathode. The oxidation state of X in the molten state is?

I found the number of mol e-, which was 7.46*10^(-1), but I didn't know where to go from here.

Any help would be _greatly_ appriciated!

Thanks!

.250 moles of metal X and 0.75 moles of e-. How many e-'s per metal ion?
 

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