3.1 - Redox and Standard Electrode Potential Flashcards
Define oxidation in terms of electron transfer
Loss of electrons
Define reduction in terms of electron transfer
Gain of electrons
What is a redox reaction?
A redox reaction is a reaction in which oxidation and reduction occur on different species simultaneously.
What is standard electrode potential?
Standard electrode potential is the potential across the electrodes when a redox system is connected to a hydrogen half-cell under standard conditions.
What conditions are required for measuring the standard electrode potential?
- 298 K temperature
- 100 kPa pressure
- 1.00 mol dm-3 concentration of ions
Why is a hydrogen half-cell needed as a reference?
The hydrogen half cell is used to allow for easy comparison between the electrode potential of different elements. The standard electrode potential for hydrogen is assumed to be zero volts at any temperature.
What is the experimental setup to calculate the standard electrode potential for zinc?
Why must metal electrodes be cleaned with sandpaper before creating an electrochemical cell?
To remove any metal oxide that has formed on the surface and improve electrical conductivity.
Describe the movement of electrons in an electrochemical cell
Electrons flow through the wire from the positive electrode to the negative electrode.
Why is a salt bridge used in an electrochemical cell?
- To maintain the charge balance and complete the circuit.
- Negative electrons are moving from one half cell to another. Without the salt bridge, positive charge would build up in the half cell containing the anode and negative charge would build up in the half cell containing the cathode. This would cause the reaction to stop.
Why must an inert salt be used in the salt bridge?
The salt must be inert so that it doesn’t react with the solutions and alter the ion concentrations. If a reactive salt was used, the cell potential would change.
What moves across the salt bridge?
Ions
For what range of cell potential values is a process feasible?
Cell potential must be greater than 0.
How can cell potential be calculated?
Eθcell =
Eθ(positive terminal) - Eθ(negative terminal)
Why might theoretical cell potential values be different to values obtained experimentally?
Conditions may be non-standard.