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How can an electrochemical cell be manipulated to produce an optimal…
How can an
electrochemical cell
be manipulated to produce an
optimal energy output
?
Concentration of electrolytes
As the concentration of the electrolyte increases, the number of particles that can react with the electrode increases. Thus, more electrons flow through the system and the current and potential difference will also increase.
Aim:
To determine the effect of change in surface area of an anode on the potential difference of a galvanic cell
Controlled Variables
Anode and Cathode
Anode and cathode will have to remain the same, as they may have differing electric potentials
Electrolyte at the cathode
As the concentration will change in the electrolyte at the anode, the concentration at the cathode must stay the same to remove the effect of the amount of atoms reacting with an electrode
Salt Bridge
As the salt bridge may impact the potential difference, the solution will be kept the same throughout the trials
Electrolyte temperature
As temperature will increase the average kinetic energy of particles within an electrolyte, this must stay controlled
Materials
Zinc Metal
Zinc Sulphate
1 mol/L
0.5 mol/L
0.1 mol/L
2 mol/L
Copper Metal
Copper Sulphate
Beakers
Wire/Voltmeter
Potassium Chloride Salt Bridge
Potential Errors
Exact concentration
In order to maintain the exact concentration of the electrolyte, a volumetric flask will be used. However, due to parallax error and other errors, the concentration may not be exact.
Electrolyte temperature
As the temperature of the electrolyte may be different when in use, this could impact the number of successful collisions at the electrode. Thus, increasing the potential difference.
Surface Area
As the surface area cannot be controlled unless the entire electrode is placed into the electrolyte, this may impact the overall results for potential difference
Electrodes
Electrodes have a relative potential based on their reactivity. Thus, a potential difference is created between two electrodes in a galvanic cell
Aim:
To determine how a changing electrode will influence the potential difference of the galvanic cell
Controlled Variables
Copper Cathode
The copper cathode will have to be controlled and the anode will be changed. Thus, the y-int will be used for accuracy
Beakers
The beakers will be cleaned between trials and kept the same
Wires/Voltmeter
Changing the wires and voltmeter may impact the overall results as these wires have been aged over time. The voltmeter's will also have to be controlled, as several used in the class show differing results due to their age
Salt Bridge Solution
Differing salt bridge solutions may have differing impacts on the potential difference. Thus, they remained constant
Materials
Zinc Anode
Copper Cathode
Iron Nail
Magnesium
Aluminium
Beakers
Salt Bridge
Voltmeter
Alligator Clips
Respective electrolyte for each anode/cathode
Potential Errors
Purity of Metals
Metals used in the practical may not be pure and oxidise with the air. This could impact the relative potential of the metals
Concentration of the electrolytes
This variable may be hard to control as the electrolytes will not be pure and the number of moles in the electrolytes will be difficult to control.
Surface Area of the electrodes
It will also be hard to control the surface area of the metals when they are placed into the electrolyte. As the clip may react with the electrolytes and impact the results, the metals will have to be held above the electrolyte
Temperature of electrolytes
When the temperature of an electrolyte increases, the particles within the electrolyte have a greater kinetic energy and thus activation energy. Hence, they should collide more frequently and successfully with the electrode and increase potential difference
Aim:
To determine how an increase in temperature impacts the voltage of a galvanic cell
Controlled Variables
Cathode/Anode
The cathode and anode material will be controlled as they will have differing relative potentials and a large impact on the potential difference
Electrolyte
The same electrolyte was used as changing the electrolyte may change the rate of oxidation and movement of electrons throughout the system
Beakers
The same two beakers will be used and cleaned throughout the practical
Salt Bridge
The same salt bridge solution will be used in order to minimise the impact of a changing salt bridge on the potential difference
Materials
Zinc
Zinc Sulphate
Copper
Copper Sulphate
100mL Beakers
Heating Mantle
Salt Bridge
Thermometer
Potential Errors
Concentration of electrolyte
As an increase in moles in an electrolyte will increase the number of collisions with the electrode, this will have to be controlled. However, as the electrolyte may not be pure, the concentration may be uncontrolled
Surface Area of Metals
As the electrodes were hung above the electrolytes, the surface area is unable to be controlled throughout the practical
Temperature Accuracy
Whilst increasing the temperature is possible with a heating mantle, when transferring the solutions to a galvanic cell, the temperature may decrease. Furthermore, whilst recording data, the temperature may also decrease and impact the potential difference recorded
Surface Area
As the surface area of the electrode increases, the number of atoms that are able to react at the surface of the electrode increases and the potential difference should increase with surface area
Aim:
To determine the impact of an increase in surface area of an electrode on the potential difference of a galvanic cell
Controlled Variables
Anode/Cathode
As the surface area of the anode is changing, the same anode and cathode material will be used throughout the trials
Temperature of electrolyte
As an increase in temperature may increase the number of collisions at the anode and cathode, this will be controlled by maintaining room temperature for the electrolytes
Electrolyte
As the surface area of the anode is changing, the volume of the electrolytes will stay the same throughout the practical
Materials
Zinc Metal
Cut at 4 different surface areas determined during the practical
Potential Errors
As the electrodes will be held above the electrolyte, the surface area will be difficult to determine for each of the electrodes and this may impact the potential difference
The Problem?
"Optimal Energy Output"
Potential Difference (∆V)
Potential difference is the difference in potential energy between two points in a circuit. In a galvanic cell, the potential difference is the difference in electric potential between the anode and the cathode
Current (I)
Current is the number of electrons that transfer over one point in a circuit. In this case, the current is the number of electrons transferred at a point between the cathode and anode
Resistance (R)
Resistance is the relative ability of the opposition of electron flow in a circuit. This could occur between the wires as the system is left on for a long period of time
"Electrochemical Cell"
Wires
Nichrome wires are used between the two electrodes to connect the circuit
Electrolyte
An electrolyte is a substance that coats the anode and removes substances from the anode
Electrode
Metals that undergo oxidation and reduction to transfer electrons within the system