Youtube Lessons on Electrochemistry
Lab: Electrochemistry – Nernst Equation
Purpose of the lab:
To determine the cell potential of the standard galvanic cell and study the effect of changing concentration on the emf of a cell.
Materials:
1.Beakers 2×250 mL. 6 x 100 mL
2.Porous porcelain jar one size 25 mL
3.Copper strips (3cm x 2cm strips one)
4.Zinc strips (3cm x 2cm strips one)
5.Copper wire as needed
6.Crocodile clips if you have them or become creative
7.Digital multi meter or voltmeter
Procedure:
1.Prepare 1 M solution of CuSO4.5H2O about 200 mL. Dilute it sequentially to produce at least five different concentrations. For example 1M, 0.5M, 0.25M 0.0125 and 0.0612M. To do this take 50 ml of 1M solution and add 50 mL distilled water, repeat this until you get 5 set of solutions with different concentrations.
2.Prepare 1M solution of ZnSO4 about 100 mL
3.Add the five different copper sulfate solutions prepared into the 5, 50 or 100 mL glass beakers, use the same volume.
4.Connect the copper metal strips and attach it to copper wires and attach it to the multi meter or voltmeter.
5.Connect the zinc metal strip to a copper wire and attach to the multi meter or voltmeter
6.When you are ready fill the porous cup 3/4th with the zinc sulfate solution, add the zinc metal strip into it and immerse the porous cup into the beakers which contain the copper sulfate solution in sequence.
7.First immerse it into the 1 M solution and record the cell potential developed. Now remove the porcelain cup rinse the outside with distilled water and immerse it in the remaining solution and record the data collected.
8. Once you are done dispose off all the solutions in the disposing jar for inorganic salts placed on the lab bench.
9.Put away all lab equipment’s clean your lab station.
10.Calculate the cell emf for the different concentrations and compare it to the measured value.
11.Plot a graph of concentration of copper sulfate solution vs emf of the cell
Data Sheet
Make a table to collect data
Discussion questions and Calculations
1.Which is the anode in the electrochemical cell?
2.Which is the cathode in the electrochemical cell?
3.What is the value of Eocell for this cell?
4.Write the oxidation half reaction, reduction half reaction and net cell reaction, for the reaction?
5.Write Nernst equation and show calculation for trials 2 to 5
6.What is the function of the porous partition in this electrochemical cell, what will be a comparable device that can be used to replace the porous partition in an electrochemical cells explain your answer.
7.Draw a graph of Concentration of copper ions Vs Emf and comment on the trend that you observe.
8.What reasons would you have for any discrepancy you may have observed?
9.Using Nernst equation, if you are to make a prediction, what would be the effect of temperature on the emf of an electrochemical cell, if the temperature is raised from 25oC to 35oC.
10.What would happen to the emf of the cell if water is added to dilute the zinc solution in the porous partition? Explain your answer using the concept of equilibrium.
11.How you modify this experiment to make a reactivity series for metals like lead, iron, tin and silver, answer should be brief and in point form.
Write a lab report and answer the above discussion questions
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