Electrochem Lab Report

Jenna Simmons
Arjun Dhura
William Sale
Guided Inquiry Lab - Building Electrochemical and Electrolytic Cells
Part 1:
Objectives:
1. Construct 2 electrochemical cells and measure their voltages
2. Find 2 ways to alter the voltage of one of the electrochemical cells
Materials:
● 3 beakers (250mL)
● Electrode clamps
● Multimeter
● Copper strip
● Aluminium strip
● U-shaped tube
● 2 cotton balls
Chemical reagents:
● NaNO3
● Zn(NO3)2 - 6H2O
● Al(NO3)2 - 9H2O
● Cu(NO3)2 - 3H2O
Procedure:
1. Weigh out solids and add to separate clean 250mL beakers
2. Fill beakers to 100mL with water and stir to dissolve
3. Transfer solutions to clean 100mL beakers
4. Fill U-shaped tube with sodium nitrate solution until completely full and block the
ends of the tube with cotton balls
5. Carefully place salt bridge into both solutions cotton ball side down
6. Connect copper and aluminium strip to electrode clamps and place them inside the
two solutions making sure to add the copper electrode to the copper solution and
vice versa
7. Clamp multimeter on the electrodes and put into solutions
8. Record voltage of the current system
Voltage tweaks:
9. Dilute each solution to 0.1M less of its original and measure voltage again
Calculations:
Figure (i): Mass calculations
Part 2:
Objectives:
Construct a type 3 electrolytic cell for electroplating copper onto iron nail.
● Materials:
● Iron nail
● Copper
● Wires
● Batteries
● 250mL Beaker
Chemical reagents:
● CuSO4 - 5H2O
● NaNO3
Procedure
1. Prepare 100mL of Copper (II) Sulfate solution of 0.5M concentration
2. Clean a copper plate and an iron nail using steel wool
3. Insert a piece of copper in the CuSO4 solution as a donor and wire it to the negative
terminal of the battery
4. Connect the iron nail to a piece of copper wire which will be attached to the positive
end of the battery
5. Dip the iron nail in the CuSO4 solution, making sure to avoid the donor copper plate
6. Take out the the nail after a minute
Calculations:
Figure (i): Mass calculations
Analysis
Part 1
4) To alter the voltage, both solutions of Copper (ii) Nitrate and Aluminum Nitrate were
diluted by increments of 0.1M. Reducing the concentration of the solutions resulted in a
decrease of voltage after each dilution. It was expected that the solution would not change in
voltage as according to Nernst's equation the ratio of potential difference should not affect
the voltage of the cell if it is constant, i.e. 1/2 = 0.5 = 2/4. This change therefore could be
attributed to numerous unaccounted variables. A major problem was most likely the
increasing resistance of the minerals in the water as it was not distilled. In the future this can
be avoided by making smaller samples of dilutions to avoid buildup of resistance from the
water.
Concentration (M) of Copper Volume (mL) Voltage (V)

solution
0.5 100 0.96
0.4 125 0.93
0.3 166.67 0.89
0.2 250 0.74
0.1 500 0.69

Part 2
3)The minimum voltage required for this reaction was 0V because the two half reactions are
equal to each other in magnitude.
4) The variable altered in this experiment was the voltage applied. Ranging from 0V applied
to 6V were applied in increments of 1.5V. When voltage was increased, the plating process
took less time to complete. Increasing the voltage resulted in a darker colour coating when
compared to trials with less applied voltage.
Conclusion
In this experiment, electrochemistry was applied and tested in an electrolytic cell and an
electrochem cell. Part 1’s setup involved the preparation of two solutions, Copper Nitrate and
Aluminum Nitrate. Two cathodes, Copper and Aluminum were put into their respective
solutions with a salt bridge of Sodium Nitrate connecting both solutions. Voltage was then
recorded in the system. The relationship between voltage and molarity was tested. In the
experiment it was discovered that a lower concentration results in a lower voltage. Referring
to the graph (Voltage vs Molarity) the trend of the line appears to go downward. This further
proves that the real-life data gained from the experiment shows that as the solution was
continuously diluted, it also lost voltage as a system. In part 2’s set up, a Copper Sulphate
solution was prepared along with a copper anode and iron nail. The purpose of this part of
the lab was to test out the Electrolytic cell and how electroplating functions. It was found that
when the iron nails or pencil lead was dipped into the system, over time the electroplating
came into effect and coated the objects in copper. Voltage was manipulated to determine
any changes it may have on the electroplating process. It was concluded that as the voltage
increased, the electroplating took less time to finish. It was also evident that the results from
the process resulted in a darker coating as voltage increased. From this lab, the cause and
effect of electrochemistry was explored through an electrochem cell and an electrolytic cell.
The connection between molarity and voltage was distinguished as well as the connection
between voltage and electroplating. The knowledge gained from this lab can be applied to
electroplating of certain metal hardware, which can prevent corrosion. The process can also
be maximised towards efficiency knowing the relationship of voltage and electroplating time.

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Jenna Simmons

Concentration (M) of Copper Volume (mL) Voltage (V)

0.5 100 0.96

0.4 125 0.93

0.3 166.67 0.89

0.2 250 0.74

0.1 500 0.69

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