Investigating the Effect of Different Concentrations of Copper (II) Sulfate and Different
Half-Cells (Fe and Al) on the Electromotive Force (EMF) of a Voltaic Cell
Word count: 2879 words
Introduction
Electrochemical cells, particularly voltaic cells, have been transformative in energy generation
and storage. These cells convert chemical energy into electrical energy through spontaneous
redox reactions. They are widely used in various applications, from powering portable
electronics to renewable energy storage systems. Notably, voltaic cells are considered
environmentally friendly as they do not emit greenhouse gases directly, making them ideal for
sustainable energy solutions (Amayreh, 2022).
My interest in this topic originates from an interest in how my phone functions. Upon
researching, I discovered that phones and other electronic devices rely on electrochemical cells,
specifically voltaic cells, to power their operations. This inspired me to explore the principles
behind these cells and their potential for efficient and sustainable energy production. My
investigation focuses on how the concentration of copper (II) sulfate in a voltaic cell affects its
EMF, using Al and Fe half-cells.
I chose the aluminum-copper voltaic cell for its numerous advantages and applications.
Aluminum, a lightweight and abundant metal, makes this system particularly suitable for
weightless batteries used in portable electronics and energy storage. Additionally, both aluminum
and copper are cost-effective materials, making this combination appealing for small-scale
energy production (Elia et al., 2021).
The inclusion of an iron-copper voltaic cell in the study allows for a comparative analysis with
the aluminum-copper system. Iron and copper are also abundant and affordable, making them
practical for small-scale applications. By comparing these two metal combinations, the study
aims to examine how the choice of anode affects the efficiency and EMF of the voltaic cells,
providing insights into their potential applications in energy storage.
1
,Research Question
How does changing the concentration of copper (II) sulfate solution (1.0 M, 0.8 M, 0.6 M, 0.4
M, and 0.2 M) affect the EMF (V) of a voltaic cell with Fe/Cu²⁺ and Al/Cu²⁺ half-cells, as
measured by a voltmeter, while maintaining other conditions constant?
Background Information
A voltaic cell (also known as a galvanic cell) converts chemical energy into electrical energy. It
consists of two half-cells, each containing a metal electrode immersed in an electrolyte solution
of its ions. The two half-cells are connected by a wire to allow electron flow and a salt bridge to
maintain electrical neutrality. The reaction in a voltaic cell is driven by redox processes. At the
anode, the metal is oxidized (Ox.), releasing electrons into the external circuit, while at the
cathode, reduction (Red.) occurs as electrons are gained by ions in the solution. The electrical
current flows in the circuit from the anode to the cathode. This movement of electrons generates
a potential difference across the two electrodes in the voltaic cell, that can be measured
accurately using a multimeter or a voltmeter (Libretexts, 2023).
A 1.0 M sodium chloride (NaCl) solution is used in the salt bridge to connect the two half-cells.
It allows the flow of ions between the cells, maintaining charge balance and enabling the
continuous flow of electrons, which is essential for electricity generation (Chang & Overby,
n.d.).
For the aluminum-copper cell, aluminium is oxidized since it is a highly reactive metal, while
copper undergoes reduction. That's why aluminium loses 3 electrons (Eq. 1) while copper gains
the 2 electrons from aluminium half - cell (Eq. 2) and from this the net ionic equation can be
established (Eq. 3):
3+ −
Anode: 𝐴𝑙(𝑠) → 𝐴𝑙 (𝑎𝑞) + 3𝑒 Ox. (Eq. 1)
2+ −
Cathode: 𝐶𝑢 (𝑎𝑞) + 2𝑒 → 𝐶𝑢(𝑠) Red. (Eq. 2)
2+ 3+
Overall Eq.: 2𝐴𝑙(𝑠) + 3𝐶𝑢 (𝑎𝑞) → 2𝐴𝑙 (𝑎𝑞) + 3𝐶𝑢(𝑠) (Eq. 3)
2
, In the iron-copper cell, iron, being more reactive, oxidizes by losing 2 electrons (Eq. 4), while
copper reduces by gaining 2 electrons (Eq. 5). The net ionic equation is shown in Eq. 6.
2+ −
Anode: 𝐹𝑒(𝑠) → 𝐹𝑒 (𝑎𝑞) + 2𝑒 Ox. (Eq. 4)
2+ −
Cathode: 𝐶𝑢 (𝑎𝑞) + 2𝑒 → 𝐶𝑢(𝑠) Red. (Eq. 5)
2+ 2+
Overall Eq.: 𝐹𝑒(𝑠) +𝐶𝑢 (𝑎𝑞) → 𝐹𝑒 (𝑎𝑞) + 𝐶𝑢(𝑠) (Eq. 6)
The EMF (𝐸) can be calculated using the Nernst equation:
𝑜 𝑅𝑇
𝐸 = 𝐸 − 𝑛𝐹
𝑙𝑛𝑄 (Eq. 7)
𝑜 −1 −1
Where 𝐸 is the standard EMF, R is the universal gas constant (8.31 𝐽 𝑚𝑜𝑙 𝐾 ), T is the
temperature (K), n is the number of electrons transferred, F is the Faraday constant (96485
−1
𝐶 𝑚𝑜𝑙 ). Q is the reaction quotient which is a measure of the ratio of the concentrations of the
products to the concentrations of the reactants, each raised to the power of their stoichiometric
coefficients (Libretexts, 2023a).
This equation shows that the concentration of ions, in this case, Cu²⁺, directly impacts the EMF
of the cell. Thus, the following hypotheses were assumed:
Hypotheses
Higher concentrations of copper (II) sulfate increase the availability of reactant ions, enhancing
the reduction process and resulting in a higher EMF of the voltaic cell.
Furthermore, the choice of half-cell (aluminum or iron) will affect the EMF of the voltaic cell
due to differences in their electrode potentials. Aluminum, being more reactive than iron, is
expected to produce a higher EMF when paired with copper (II) sulfate.
Current literature on this topic is scarce, particularly regarding the specific combinations of
copper, aluminum, and iron half-cells. However, student research "The Effect of Copper (II)
Sulfate (CuSO₄(aq)) Solution Concentration on the Cell Potential of a Voltaic Cell When
3
Half-Cells (Fe and Al) on the Electromotive Force (EMF) of a Voltaic Cell
Word count: 2879 words
Introduction
Electrochemical cells, particularly voltaic cells, have been transformative in energy generation
and storage. These cells convert chemical energy into electrical energy through spontaneous
redox reactions. They are widely used in various applications, from powering portable
electronics to renewable energy storage systems. Notably, voltaic cells are considered
environmentally friendly as they do not emit greenhouse gases directly, making them ideal for
sustainable energy solutions (Amayreh, 2022).
My interest in this topic originates from an interest in how my phone functions. Upon
researching, I discovered that phones and other electronic devices rely on electrochemical cells,
specifically voltaic cells, to power their operations. This inspired me to explore the principles
behind these cells and their potential for efficient and sustainable energy production. My
investigation focuses on how the concentration of copper (II) sulfate in a voltaic cell affects its
EMF, using Al and Fe half-cells.
I chose the aluminum-copper voltaic cell for its numerous advantages and applications.
Aluminum, a lightweight and abundant metal, makes this system particularly suitable for
weightless batteries used in portable electronics and energy storage. Additionally, both aluminum
and copper are cost-effective materials, making this combination appealing for small-scale
energy production (Elia et al., 2021).
The inclusion of an iron-copper voltaic cell in the study allows for a comparative analysis with
the aluminum-copper system. Iron and copper are also abundant and affordable, making them
practical for small-scale applications. By comparing these two metal combinations, the study
aims to examine how the choice of anode affects the efficiency and EMF of the voltaic cells,
providing insights into their potential applications in energy storage.
1
,Research Question
How does changing the concentration of copper (II) sulfate solution (1.0 M, 0.8 M, 0.6 M, 0.4
M, and 0.2 M) affect the EMF (V) of a voltaic cell with Fe/Cu²⁺ and Al/Cu²⁺ half-cells, as
measured by a voltmeter, while maintaining other conditions constant?
Background Information
A voltaic cell (also known as a galvanic cell) converts chemical energy into electrical energy. It
consists of two half-cells, each containing a metal electrode immersed in an electrolyte solution
of its ions. The two half-cells are connected by a wire to allow electron flow and a salt bridge to
maintain electrical neutrality. The reaction in a voltaic cell is driven by redox processes. At the
anode, the metal is oxidized (Ox.), releasing electrons into the external circuit, while at the
cathode, reduction (Red.) occurs as electrons are gained by ions in the solution. The electrical
current flows in the circuit from the anode to the cathode. This movement of electrons generates
a potential difference across the two electrodes in the voltaic cell, that can be measured
accurately using a multimeter or a voltmeter (Libretexts, 2023).
A 1.0 M sodium chloride (NaCl) solution is used in the salt bridge to connect the two half-cells.
It allows the flow of ions between the cells, maintaining charge balance and enabling the
continuous flow of electrons, which is essential for electricity generation (Chang & Overby,
n.d.).
For the aluminum-copper cell, aluminium is oxidized since it is a highly reactive metal, while
copper undergoes reduction. That's why aluminium loses 3 electrons (Eq. 1) while copper gains
the 2 electrons from aluminium half - cell (Eq. 2) and from this the net ionic equation can be
established (Eq. 3):
3+ −
Anode: 𝐴𝑙(𝑠) → 𝐴𝑙 (𝑎𝑞) + 3𝑒 Ox. (Eq. 1)
2+ −
Cathode: 𝐶𝑢 (𝑎𝑞) + 2𝑒 → 𝐶𝑢(𝑠) Red. (Eq. 2)
2+ 3+
Overall Eq.: 2𝐴𝑙(𝑠) + 3𝐶𝑢 (𝑎𝑞) → 2𝐴𝑙 (𝑎𝑞) + 3𝐶𝑢(𝑠) (Eq. 3)
2
, In the iron-copper cell, iron, being more reactive, oxidizes by losing 2 electrons (Eq. 4), while
copper reduces by gaining 2 electrons (Eq. 5). The net ionic equation is shown in Eq. 6.
2+ −
Anode: 𝐹𝑒(𝑠) → 𝐹𝑒 (𝑎𝑞) + 2𝑒 Ox. (Eq. 4)
2+ −
Cathode: 𝐶𝑢 (𝑎𝑞) + 2𝑒 → 𝐶𝑢(𝑠) Red. (Eq. 5)
2+ 2+
Overall Eq.: 𝐹𝑒(𝑠) +𝐶𝑢 (𝑎𝑞) → 𝐹𝑒 (𝑎𝑞) + 𝐶𝑢(𝑠) (Eq. 6)
The EMF (𝐸) can be calculated using the Nernst equation:
𝑜 𝑅𝑇
𝐸 = 𝐸 − 𝑛𝐹
𝑙𝑛𝑄 (Eq. 7)
𝑜 −1 −1
Where 𝐸 is the standard EMF, R is the universal gas constant (8.31 𝐽 𝑚𝑜𝑙 𝐾 ), T is the
temperature (K), n is the number of electrons transferred, F is the Faraday constant (96485
−1
𝐶 𝑚𝑜𝑙 ). Q is the reaction quotient which is a measure of the ratio of the concentrations of the
products to the concentrations of the reactants, each raised to the power of their stoichiometric
coefficients (Libretexts, 2023a).
This equation shows that the concentration of ions, in this case, Cu²⁺, directly impacts the EMF
of the cell. Thus, the following hypotheses were assumed:
Hypotheses
Higher concentrations of copper (II) sulfate increase the availability of reactant ions, enhancing
the reduction process and resulting in a higher EMF of the voltaic cell.
Furthermore, the choice of half-cell (aluminum or iron) will affect the EMF of the voltaic cell
due to differences in their electrode potentials. Aluminum, being more reactive than iron, is
expected to produce a higher EMF when paired with copper (II) sulfate.
Current literature on this topic is scarce, particularly regarding the specific combinations of
copper, aluminum, and iron half-cells. However, student research "The Effect of Copper (II)
Sulfate (CuSO₄(aq)) Solution Concentration on the Cell Potential of a Voltaic Cell When
3
