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How can you design an electrochemical cell that produces an optimal energy…
How can you design an electrochemical cell that produces an optimal energy output?
Types of electrochemical cells
Galvanic Cell / Voltaic Cell
Converts chemical energy to electrical energy
Types of Galvanic / Voltaic cells
Fuel cell
Metal half cell
Half cells with inert electrodes
Components: Cathode, anode, two half cells, salt bridge, electrolytes
Electrolytic Cell
Converts electrical energy to chemical energy.
Energy output
How can optimal energy be measured?
Mass of electrodes
Mass of cathode increases as aqueous ions turn to solid, while mass of anode decreases as the reacting anode material becomes aqueous. Therefore, the greater the increase of mass, the greater the rate of electrolysis
Voltage
A voltmeter measuring the potential difference, or voltage, between two points in an electrical or electronic circuit.
What increases energy output?
Insertion of two pairs of anodes and cathodes into a single volume of an electrolyte.
Increasing concentration of electrolytes
This shifts equilibrium in forwards direction, and increases the number of successful collisions.
Increase voltage
Increasing surface area of electrodes
Increases ions able to stick to cathode
Increasing temperature
This increase in energy (heat) causes particles to vibrate faster, increasing the number of successful collisions. A greater proportion of particles will contain enough energy to overcome activation energy.
Factors affecting conductivity
Salt bridge: Connects the oxidation and reduction half-cells, in order to complete the inner circuit and maintain the electrical neutrality of the electrolytic solutions of the half-cells
Amount: The more salt bridges present, the less internal resistance that occurs, therefore the smaller the voltage drop and the larger the measured voltage from the cell. (WithNail, 2014)
Type of salt bridge
Sodium Chloride, Potassium Chloride, or Potassium Nitrate.
Potential independent variables
Voltage across the cell- affects current
Concentration of electrolyte- affects current
Elements used for electrodes- affects difference in standard electrode potential and electrochemical equivalent
Distance between electrodes- affects resistance, which affects current
Surface area of electrodes- afects current
Type of electrolyte used - different electrolytes have different products of electrolysis
Temperature of electrolyte- affects resistance, affecting current
Potential dependent variables
change in mass of an electrode- the anode will lose mass, measured with electronic balance
Time taken to electroplate a controlled mass- measured by measuring time taken to completely cover and electrode
Change in concentration of solution- measured via titration after each trial
Change in mass of the solution- measured using electronic balance
Volume of gas produced- measured by collecting gas in a syringe and identifying the volume
Factors to consider
Environmental concerns
Toxicity and safety hazards
Costs and availability of equipment and materials