Electrochemistry Flashcards
Redox reaction
A reaction involving the transfer of electrons
Oxidation
The loss of electrons
Reduction
The gain of electrons
An oxidising agent
A substance that accepts electrons
A reducing agent
A substance that donates electrons
Anode
The electrode where oxidation takes place
Cathode
The electrode where reduction takes place
Electrolyte
A substance that can conduct electricity due to the presence of free (mobile) ions when molten or dissolved in solution
What is a spectator ion?
Ions that do not take part in the electron transfer in a redox process
Describe a galvanic cell
An electrochemical cell that converts the chemical energy of spontaneous redox reactions into electrical energy
In a galvanic cell, where at which half-cell does oxidation take place?
Anode
In a galvanic cell, where at which half-cell does reduction take place?
Cathode
In a galvanic cell, where at which half-cell does reduction take place?
Cathode
In a galvanic cell, what reaction takes place at the anode?
Oxidation
In a galvanic cell, what reaction takes place at the cathode?
Reduction
What are the functions of the salt bridge, in a galvanic cell?
- completes the circuit
- maintains electrical neutrality in the half-cells
What is an inert electrode?
A electrode that does not participate in an electrochemical reaction
Until which point can a galvanic cell deliver current?
The galvanic cell has the capacity to deliver current until the reaction reaches chemical equilibrium or has run to completion
When does the voltage of a galvanic cell equal zero?
Once a galvanic cell reaches chemical equilibrium or has run to completion
What is internal resistance in relation to galvanic cells?
Internal resistance is opposition to the flow of charge through the electrodes and electrolytes in a cell
What is the effect of an increased surface area of the electrodes in a galvanic cell?
- The rate of reaction increases by lowering the internal resistance
- maximum current that the cell can deliver increases but this does not effect the emf of the cell
What effect does a wider, shorter and/or more conductive salt bridge have in a galvanic cell?
Internal resistance lowers thereby increasing the maximum current that the cell can deliver but this does not affect the emf of the cell
Describe an electrolytic cell
An electrochemical cell that uses electrical energy to cause non-spontaneous redox reaction to occur. Thus, electrical energy is converted into chemical energy.
Which terminal is the anode of an electrolytic cell?
Positive terminal
Which terminal is the cathode of the electrolytic cell?
Negative terminal
What type of emf indicates a spontaneous redox reaction under standard conditions?
Positive values if the standard emf
What type of emf indicates a non-spontaneous redox reaction under standard conditions?
Negative values of the standard emf
What are two observable differences between galvanic and electrolytic cells?
Galvanic:
- has a salt-bridge
- occurs within two beakers
Electrolytic:
- does not have a salt-bridge
- occurs in one beaker
What is the purpose of a catalyst in an electrolyte?
Improves conductivity of the electrolyte aqueous solution
What construction change in a galvanic cell would increase the maximum current produced in the cell?
- increase the surface area of the electrodes
- increase the concentration of the electrolyte
- use a wider or more conductive salt-bridge
