Part A: Investigating the Transfer of Electrons Via the Reactivity of Metals in Solutions
Observations of the reactions of several unknown metals with corresponding metal salt solutions. (16 marks)
Question 1: Based on your observations of each metal/solution pair, indicate which metal is the anode and which is the cathode in each reaction. Click the appropriate box for each column. (6 marks)
Question 2: Using Zinc and Copper as an example, show the complete half-cell reactions for the redox reaction between these two metals, and then give the cell notation for an electrochemical cell using these two metals as electrodes. Note: You will need to complete these equations in another program (such as equation editor in MS Word) and then insert as an image below. (4 marks)
Part B: Preparing Electrolyte Solution and the Electrochemical Half-Cell.
Preparation of an approximately 1.0M solution of potassium nitrate (KNO3) (2 marks)
Mass of KNO3 solid added to beaker (g)
Total Volume of solution (mL)
Question 3: Calculate the exact concentration of your KNO3 solution. Show the complete calculation.
You will need to insert your calculation as an image below. (3 marks)
Part C: Identification Unknown Metal/Metal Solutions using Ecell Measurements
Measured Ecell readings of various pairs of unknown metals with corresponding salt solutions using an electrochemical half-cell. (3 marks)
Question 4: Calculate the standard cell potential, Eocell, for each of the possible pairs of metals. Show one complete sample calculation (using one pair of metals) then complete Table 4. Note: you will need to determine which is the anode and which is the cathode for each pair. (2 marks)
Calculated standard cell potential, Eocell , values of various pairs of metals in an electrochemical half-cell. (6 marks)
Metal Pair, Eocell (V)
Copper and Iron
Copper and Zinc
Copper and Magnesium
Iron and Zinc
Iron and Magnesium
Zinc and Magnesium
Question 5: Based on your observations of the reactivity in Part A and the voltage readings obtained from Part B for each pair of metals, place each unknown metal in the correct order in respect to the electrochemical series with the strongest oxidizing agents at the top of the list and the strongest reducing agents at the bottom. (4 marks)
Question 6: Compare your list of reactivities and theoretical Ecell values to identify each of the unknown metals (4 marks)
Question 7: Measured cell potential are often different from theoretical values. Compare the measured potential to the theoretical values and calculate the percent error for each pair of metals (using your previous identification). Show one complete sample error calculation (using one pair of metals) then complete Table 5. You will need to insert your calculation as an image below (2 marks)
Comparison of measured standard cell potential, Eocell , values vs. theoretical values of identified unknown pairs of metals in an electrochemical half-cell. (8 marks)
Part D: Cu2+ Concentration and the Nernst Equation
Question 8: Calculate the concentration of Cu2+ in each diluted CuSO4 solution. Show one complete
sample calculation, then tabulate the other solutions (Table 5). Insert your calculation as an image. (3 marks)
Measured Ecell readings for electrochemical cell using Cu and Zn as electrodes with varying Cu2+ concentration and constant Zn2+ concentration (0.5M) (5 marks)
Question 9: How does the concentration of the solutions effect the measured voltage? (2 marks)
Question 10: Use the Nernst equation to calculate the theoretical Ecell value for the “stock” solution of Cu2+ with a 0.50M Zn2+solution (3 marks)
Question 11: Construct a Nernst plot of Ecell vs ln[Cu2+], from Table 6. Your plot should include a line of best fit, the equation the line (with the y-intercept and slope) and best fit (R2) values to 3 decimal places. You are encouraged to use an appropriate graphing program to complete the plot electronically. Graphs should follow the graphing format provided in Student Laboratory Handbook. You will need to save your graph as an image then insert into the box below: (5 marks)
Question 12: Using the equation of the line from your Nernst plot, calculate the concentration of a Cu2+ solution that gives a Ecell reading of 1.02V (2 marks)
Sample Solution