EMS630U Electrochemical Potentials Experiment Lab Report Assignment Sample

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1. Introduction to Electrochemical Potentials

Electrochemical potentials describe how strongly electrons are driven to move between reacting species in a redox system, linking chemical change to measurable voltage in an electrochemical cell. They arise from paired oxidation and reduction half‑reactions at separate electrodes, where differences in metal reactivity and ion concentration create a potential difference that can be harnessed as electrical energy. Understanding this concept is essential for interpreting how batteries, corrosion processes, and energy storage devices operate and for predicting how changes in conditions such as concentration or pH will shift reaction direction and cell voltage.

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Definition

The electrochemical potential is a basic idea in electrochemistry which is the electrochemical potential energy/unit charge in a system that participates in the electrochemical reaction. The driving force for the direction and extent of redox reactions. The concept of electrochemical cells is closely related to the term, which are two half-cells arranged in a fashion such that the flow of electrons between them through an external circuit can occur giving rise to chemical transformations. Electrochemical potentials control, in these systems, the tendency of the electrons to move into the reaction from one electrode to another, determining the voltage and current in the rate generated during the reaction (Zuo et al., 2023).

EMS630U Electrochemical Potentials Experiment Lab Report Assignment Sample

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Context

Redox reactions form the basis behind the concept of electrochemical potentials which is the transfer of electrons between substances (Weltin and Kieninger, 2021). When the reaction is a redox one, one substance oxidizes (loses electrons), and the other reduces (gains electrons). The species that donates electrons is a reducing agent, and the species that accepts electrons is an oxidizing agent. The reactions are all taking place at the electrodes of an electrochemical cell and the variation of potential difference (voltage) between the two half cells will cause electrons to flow.

These electrochemical cells are used in many applications such as batteries, corrosion and energy storage systems (Saji, 2023). Electrochemical potentials drive electrons in batteries, for example, through an external circuit to supply the electrical energy that batteries can deliver to power various devices (Quilty et al., 2023). Just like the corrosion of metal takes place by electrochemical reactions at the surface of the metal like the rusting of iron, steel, may degrade in a similar manner. Reversible redox reactions store and release energy in energy storage systems such as supercapacitors and fuel cells, and also have a large impact on electrochemical potentials (Li et al., 2022).

Importance

To predict and control the behavior of different metals in different chemical environments, electrochemical potentials need to be understood. The action of a metal’s reactivity depends precisely on its electrochemical potential in the given solution: it will be stirred if it is to undergo oxidation or reduction. And from these potentials, scientists now can better design materials, for example, for things like batteries and preventing corrosion, for certain uses. For instance, there is the choice of material based on the maximum performance characteristic within an energy storage device such that the electrochemical potential of some metals dictates some material higher electrochemical potential is linked to the higher voltage, and therefore energy capacity.

Additionally, rate and direction of a reaction can be explained through the effect of concentration, pH, and temperature changes made to the electrochemical potential (Fornaciari et al., 2022). The Nernst equation, despite going a long way in calculating the electrochemical potential of a cell in nonstandard conditions provides us with the means to understand how real world conditions can negatively impact electrochemical behavior. Also, these principles help in developing efficient and green corrosion inhibitors as well as efficient renewable energy systems.

For this reason, it is necessary to know the basic processes present in the metal behaviours during chemical reactions, in the presence of electrochemical potentials. For the latter applications (i.e energy storage, corrosion prevention, environmental sustainability), their efficiency and reactivity have to be studied for some specific circumstances and their study gives insight to this.

2. Methodology and Aim of the Experiment

Experiment Aim

This experiment has been conducted to understand the electrochemical activity of the Copper (Cu), Zinc (Zn), Magnesium (Mg) and Iron (Fe) in their ionic solutions (Cu²⁺, Zn²⁺, Mg²⁺, Fe²⁺) and the dependency of the potentials on different ion pairs from the ion concentration. The Nernst equation is used to relate electrochemical potential to ion concentration and can be used in cells (Krowne, 2023).

Experimental Setup

The experiment invokes a fundamental electrochemical cell apparatus consisting of:

1. Voltmeter: To determine the electromotive force between the two half-cells.
2. Salt Bridge: Enables free flow of ions across the half-cells, maintain electrical neutrality, commonly uses inert electrolyte KNO₃.
3. Metal Electrodes: Cu, Zn, Mg, and Fe electrodes are put in their respective ionic baths (e.g., Cu in CuSO₄).
4. Ionic Solutions: 1M solutions of CuSO₄, ZnSO₄, MgSO₄, FeSO₄ are employed. The quantity of concentration will be changed throughout the experiment.
5. Multimeter: Measures the potential difference between the half-cells, essential for data collection.

Procedure Summary:

1. Preparation of Solutions: 1M stock solution of CuSO₄, ZnSO₄, MgSO₄ and FeSO₄ solutions are prepared. The sandpaper is used to clean metal electrodes to allow for the chemical reaction.
2. Making Half-Cells: Four half-cells are made by dipping metal electrodes into chemical solutions fitting for them (Cu in CuSO₄, Zn in ZnSO₄, etc.).
3. Composing of Voltaic Cells: An electrolyte bridge links the 2 half-cells promoting ionic movement and preventing a meld of the solutions. The half cells are linked by a voltmeter to monitor the potential difference (Ecell).
4. Recording Potential Differences: The voltmeter reads the potential differences with positive lead attached to the metal of the higher potential difference and the negative lead to the metal of the lower potential difference. Measurements like these help to determine the cell potential.

Nernst equation for redox is:

Where:

• is the measured potential.
• is the standard electrode potential.
• is the number of electrons transferred.
• and are the concentrations of the oxidized and reduced species.

1. Different Ion Concentration: Cu²⁺ is varied in concentration among 1M, 0.1M, 0.01M, and 0.001M while keeping the Zn²⁺ constant. Voltage measurements are made for each concentration, and the procedure is done for Zn, Mg, and Fe each with their respective solutions.
2. Data Recording and Analysis: Voltage is recorded and used to obtain the relationship between cell voltage (Ecell) to log [Cu²⁺]. Using the Nernst equation, The slopes, y-intercepts and R2 values were calculated to deminishly talk about the effect of ion concentrate on the electrochemical potential.

Such a procedure is devised for an examination of the influence of different amounts on electrochemical potentials and the study of basic mechanisms controlling these reactions.

3. Data and Data Analysis/Discussion

Question 5: Plotting Ecell vs. log [Cu²⁺]

Nernst equation yields the potential cell (Ecell) and the relation of the cell with the concentration of ion, namely, how the cell potential varies with the ion concentration.

This graph presents the current with which it depends on how much of the electrochemical cell potential (Ecell) depends on the logarithm of Cu²⁺ concentration ([Cu²⁺]). A positive linear relationship in the logarithmic concentration of Cu²⁺ and cell potential exists in the plot implying as the concentration of Cu²⁺ increases cell potential is also increasing like Nernst Equation.

This picture shows the outcome of the linear regression for the Ecell vs. log[Cu²⁺ plot. The slope is 0.0232, the y-intercept is 1.0923, and the R² value is 0.9964. The good R² value implies a strong linear correlation between the log[Cu²⁺] and Ecell, suggesting that the experimental data are in excellent agreement with a Nernst behavior. The slope is in good agreement with the expected one, therefore ensuring the reliability of the experimental setup and the analysis of the experimental data.

The equation is shown in the case of copper (Cu²⁺/Cu) such that as Cu²⁺ concentration increases, Ecell will also increase. This is because the term due to the logarithmic in the Nernst equation causes the potential to become more positive as the concentration of the copper ion increases, i.e. it becomes more and more favorable to reduce Cu²⁺ at the cathode.

From the experiment, it can be observed that with an increase in Cu²⁺ concentrations, the electrochemical potential increases resulting in higher cell voltage. This concurs with the Nernst, where the ions’ concentration is negative logarithmic to the potential. The higher voltage for the cell is generated because increasing Cu²⁺ concentration makes the reduction of Cu²⁺ at the cathode more favorable.

Finally, the Cu²⁺ concentration has a big impact on the electrochemical potential and the overall cell voltage in summary. Cell potentials increase as Cu²⁺ concentrations increase because the reduced species (Cu) is accessible for reduction more easily and therefore higher electrochemical driving force is created (Mukherjee et al., 2024). This behavior is central to all electrochemical systems, batteries and other energy storage devices in particular, in which the efficiency and performance are strongly dependent on the electrolyte ion concentration.

Question 6: Balanced Reactions and Oxidation/Reduction at Electrodes

Cu|Cu²⁺ and Zn|Zn²⁺ Half-Cells

In the case of the Cu|Cu²⁺ and Zn|Zn²⁺ half cell, zinc is oxidized at the anode. Zinc metal donates electrons to form Zn²⁺ ions, they dissolve into the solution. Copper ions (Cu²⁺) on the cathode are reduced by the gain of electrons and converted into solid copper.

The overall reaction is:

Here, Zinc reacts to undergo oxidation at an Anode, and copper ions, undergo reduction into the cathode. The flow of electrons from zinc to copper produces electrical energy.

Cu|Cu²⁺ and Ag|Ag⁺ Half-Cells

When zinc is replaced with silver (Ag|Ag⁺), it is oxidized at the anode giving rise to transition from Ag to Ag⁺ moving electrons and forming ions Ag⁺. Copper ions away from cathode are reduced same as in the previous case.

The global reaction in this case is:

In this case, silver is oxidized at the anode and copper ions are reduced on the cathode.

Oxidizing and Reducing Agents

In the Cu|Cu²⁺ and Zn|Zn²⁺ system, zinc acts as a reducing agent because it is oxidized at the anode and Cu²⁺ serves the role of an oxidizing agent because it is reduced at the cathode.

In the Cu|Cu ²⁺ and Ag|Ag ⁺ cells, silver is the reducing agent because it is oxidized at the anode and Cu²⁺ remains the oxidizing agent and is reduced at the cathode.

Electrochemical Activity at the Anode and Cathode

• Anode: Oxidation occurs in cells of both at the anode. Zinc or silver loses electrons which pass into the external circuit to the cathode.
• Cathode: At the cathode reduction reaction takes place. Copper ions lose electrons and are dropped on the cathode as solid copper.

Impact of Metal Reactivity on the Cell Reaction

The reactivity of the metals is the course of the cell reaction. Zinc is more active than copper, it readily loses electrons and hence is used as anode in Cu|Cu²⁺ and Zn|Zn²⁺ cells. The higher reactivity of zinc results in a higher cell potential. On the other hand, silver, which is not as reactive as zinc, can be anode in Cu|Cu2+ and Ag|Ag+ cells, but less so due to oxidation. The effect of this difference in reactivity is the amount of voltage that the cell produces.

Briefly, the electrochemical reactions take place according to the reactivity of metals. More reactive metals, such as a zinc metal, will now be more easily oxidized allowing the cell potential and energy produced in the cell to be total changed.

Question 7: Relationship Between Concentration and Voltage

The reaction between Cu²+ and Zn²+ in the electrochemical cell involves the exchange of electrons between metals of zinc and copper, known to the respective ionic solution. The total reaction in the cell is:

In this way, in this reaction, Cu²⁺ is the reactant because it is a reduction at the cathode to solid copper. On the other hand, Zn is oxidized at the anode to zinc ions, Zn²⁺. This redox reaction causes an electric flow from zinc to copper through the external circuit, providing energy.

Concentration and Voltage Relationship

The voltage that results from the electrochemical cell is affected by the ionic concentration in the solutions. The rate of reduction, and the amount of copper deposition, and the cell potential will rise as even more Cu²⁺ appears at the cathode. Oppositely, lower Cu²⁺ concentration results in fewer available ions for reduction and causes lower voltage. The connection between ion concentration and voltage can be comprehended from the setting of equilibrium.

As the concentrations of the ionic solutions are altered, the system will strive to re-establish a balance, upon which LeChatelier’s principle applies (Rad et al., 2023). This principle effectively means that if a system that is at equilibrium is interrupted, the system will either fail to alter its state or it will have a tendency to make some adjustments to bring things back to equity.

LeChatelier’s Principle in Action

For instance, as the concentration of Cu²⁺ is increased in the solution, the reaction will tend to favor more reduction of Cu²⁺ at the cathode so that the equilibrium of the reaction will shift towards the product side. This causes an increase in voltage, as need for more energy to expedite the reduction reaction. If copper ions concentration decreases the reaction goes in the opposite, thus becoming more difficult for the reduction of copper ions that makes the voltage lower (Liu et al., 2023).

Implications of a Greater (More Positive) Ecell Value

A higher value of Ecell implies a higher driving force for the reaction to take place in the forward direction. When it is the case for Cu|Cu²⁺ and Zn|Zn²⁺cell, a higher Ecell is achieved that indicates the reduction of Cu²⁺ to Cu was more favorable, thus the reaction will move easily in the direction of production of Cu (the product). The electrochemical potential is virtually a measure of how strongly the reaction tends to produce products.

Physically, a more positive Ecell means the system is in a favored product state (Cu and Zn²˳) and the reaction is thus able to occur spontaneously at a higher potential. This is due to the higher the amount of Cu²⁺will be, the more it can be reduced and the more electrical energy the cell, produces. On the other hand, a smaller positive (or less negative) Ecell implies that the reaction does not favor production of products, which means the reaction will not occur easily, and cell potential will be lower.

4. Conclusion

Summary

This paper studies the electrochemical potential of Cu|Cu²⁺, Zn|Zn²⁺ and Ag|Ag⁺ electrodes, especially considering the effects of Cu²⁺ concentration on the cell potential. The data indicated a direct relationship between Cu²⁺ concentration and voltage, with an increasing concentration-voltage relationship. The experiment confirmed that electrochemical potential is dependent upon ion strength. The addition of a greater amount of Cu²⁺ increases the reduction reaction at the cathode resulting in a higher cell potential. Linear regression showed a good correlation between log[Cu²⁺] and Ecell with an R² value of 0.9964, which sustains the expected behavior.

Insights

The experiment described the connection between the ion concentration and electrochemical potential. Higher and higher concentrations led to higher potentials, as expected for an electrochemical equilibrium process. When it comes to materials like batteries and fuel cells, this interaction is particularly important because voltage and efficiency need to be maximized (Wang et al., 2021). The experiment also showed that the more reactive metals like zinc, are easily oxidized, and that leads to higher cell potentials, whereas a less reactive metal comes, like silver, giving off relatively low is doubtful. Knowing the metal behavior and ion concentrations can lead to the performance optimization of the energy systems, such as batteries and corrosion protection.

Suggestions for Further Research:

Some subjects for further investigation are:

• Checking out Different Metals: Looking at other metals for example, such as iron or aluminum, may well provide new insights in the region of electrochemistry whilst enhancing the characteristics of niche applications.
• Temperature Dependency: Different temperatures could explain how electrochemical reactions and voltage change and that would be essential to systems.
• Electrochemical Kinetics: Studying oxidation and reduction kinetics at different types of electrodes can improve electrode reaction rates, fostering the widespread of energy-storing systems.
• Other Metal Ions: Studying concentration effects in systems with, e.g., Fe²⁺ or Ni²⁺ ions would shed light on electrochemical cells comprising different metal/ion systems.

Conclusion

The tests proved that Cu²⁺ concentration strongly affects EC potential. A higher Cu²⁺ regime value leads to a higher voltage. These findings are important for maximizing electrochemical cells in coupling with energy storage or prevention of bore decay. More study in different metals, temperatures, and electrochemical kinetics can probably allow electrochemical devices to be more efficient and versatile.

5. References

• Fornaciari, J.C., Weng, L.C., Alia, S.M., Zhan, C., Pham, T.A., Bell, A.T., Ogitsu, T., Danilovic, N. and Weber, A.Z., 2022. Mechanistic understanding of pH effects on the oxygen evolution reaction. Electrochimica acta, 405, p.139810.
• Krowne, C.M., 2023. Nernst equations and concentration chemical reaction overpotentials for VRFB operation. Journal of The Electrochemical Society, 170(10), p.100534.
• Li, X., Huang, Z., Shuck, C.E., Liang, G., Gogotsi, Y. and Zhi, C., 2022. MXene chemistry, electrochemistry and energy storage applications. Nature Reviews Chemistry, 6(6), pp.389-404.
• Liu, Y., Wang, H., Cui, Y. and Chen, N., 2023. Removal of copper ions from wastewater: a review. International journal of environmental research and public health, 20(5), p.3885.
• Mukherjee, A., Abdinejad, M., Mahapatra, S.S. and Ruidas, B.C., 2024. Controlled Synthesis of Copper Sulfide-associated Catalysts for Electrochemical Reduction of CO2 to Formic Acid and Beyond: A Review. Energy Advances.
• Quilty, C.D., Wu, D., Li, W., Bock, D.C., Wang, L., Housel, L.M., Abraham, A., Takeuchi, K.J., Marschilok, A.C. and Takeuchi, E.S., 2023. Electron and ion transport in lithium and lithium-ion battery negative and positive composite electrodes. Chemical Reviews, 123(4), pp.1327-1363.
• Rad, R.H., Brüser, V., Schiorlin, M., Schäfer, J. and Brandenburg, R., 2023. Enhancement of CO2 splitting in a coaxial dielectric barrier discharge by pressure increase, packed bed and catalyst addition. Chemical Engineering Journal, 456, p.141072.
• Saji, V.S., 2023. Corrosion and materials degradation in electrochemical energy storage and conversion devices. ChemElectroChem, 10(11), p.e202300136.
• Wang, Y., Chu, F., Zeng, J., Wang, Q., Naren, T., Li, Y., Cheng, Y., Lei, Y. and Wu, F., 2021. Single atom catalysts for fuel cells and rechargeable batteries: principles, advances, and opportunities. ACS nano, 15(1), pp.210-239.
• Weltin, A. and Kieninger, J., 2021. Electrochemical methods for neural interface electrodes. Journal of Neural Engineering, 18(5), p.052001.
• Zuo, K., Garcia-Segura, S., Cerrón-Calle, G.A., Chen, F.Y., Tian, X., Wang, X., Huang, X., Wang, H., Alvarez, P.J., Lou, J. and Elimelech, M., 2023. Electrified water treatment: fundamentals and roles of electrode materials. Nature Reviews Materials, 8(7), pp.472-490.