Electrochemistry

A galvanic cell separates a redox reaction into its two half-reactions so that electrons are transferred through an external circuit (eg, a battery) rather than by direct contact (eg, corrosion). The Nernst equation describes cell voltage under non-standard conditions.

In this experiment you will:
use electrochemistry terminology and concepts
look up and use Standard Reduction Potentials to determine spontaneity
apply the Nernst Equation in nonstandard situations
measure reduction potentials for an electrochemical series
understand the concept of a reference electrode
measure a concentration cell series and determine an unknown concentration
describe a practical application of electrochemistry
gain experience entering data and calculations into an electronic document or notebook

This experiment relies upon the Electrochemical Cells simulator

Follow the below instructions, record all your responses in your document, export the final version as a pdf, and upload the pdf file to your course D2L page by the due date.

Part 1: Background Concepts.
Go to the Electrochemical Cells simulator. Click on the Background link (top-middle of the page), and review the material. Answer the following questions for a galvanic cell with the reaction. Replace the “<text>” and “#” with your entries.

Zn(s) + Cu2+(aq) -> Zn2+(aq) + Cu(s)

1 A. Is Zn being oxidized or reduced? Why? Is Zn the anode or cathode?

<insert answer here>

1 B. Is Cu2+ being oxidized or reduced? Why? Is Cu the anode or cathode?

<insert answer here>
1 C. From the table of Standard Reduction Potentials (upper left of Simulator), write down the two half-reactions involved in this redox reaction as reductions. Also write down the Eo values for each reduction reaction from the table.

Zn2+(aq) + <text> Eo(Zn/Zn2+) = #

Cu2+(aq) + <text> Eo(Cu/Cu2+) = #

In subsequent equations, the states of matter, (s) or (aq), will be omitted since they can be presumed from the charge of the species, ie, ions are aqueous and neutral species are solids.

1 D. Calculate the Standard Electrochemical Potential of the electrochemical cell Eocell for the reaction. Show all work by replacing “#” in the equations below with your values. Include units.

Eocell = Eocathode − Eoanode

= # − ( # )

= #

1 E. What is the sign of Eocell in 1D? Is the above reaction spontaneous as written?

<insert answer here>

1 F. Assume a galvanic cell is constructed with [Zn2+] = 0.1 M and [Cu2+] = 0.0001 M. Use the Nernst Equation
E = Eocell − ( 0.0592 V / n ) * log Q

to calculate the voltage E of the cell. Show all work by replacing “#” in the equations below with your values.

E = Eocell − ( 0.0592 V / n ) * log Q

E = Eocell − ( 0.0592 V / n ) * log ( [Product Ion] / [Reactant Ion] )

E = ( # ) − ( 0.0592 V / # ) * log ( # / # )

E = # − #

E = #