Unit 3- Electrochemical Cells Flashcards
Are the strongest reducing agents positive or negative?
Negative
Define the standard electrode potential of a half-cell (Eθ)?
The standard electrode potential of a half-cell is the voltage of a half-cell compared with a standard hydrogen electrode.
Eo values are measured under specific conditions. What are they?
1M concentration of electrolyte, 298K and 1 atmosphere
How is the potential cell difference of a galvanic cell calculated?
By subtracting the cell potential of the anode from the cathode, the cell potential of the galvanic cell as a whole can be calculated. E0 = E0 reduction - E0 oxidation
In a Galvanic cell, what charge does the anode have?
Negative
In an electrolytic cell what charge does the anode have?
The anode has a positive charge.
In an electrolytic cell what charge does the anode have?
positive
Name the two types of electrochemical cells.
Galvanic and electrolytic
Standard electrode potentials are generally written as?
Reduction half equation
What are electrolytes?
An ionic substance which is either molten or an aqueous solution
What are Eo values?
The symbol represents the Cell Potential. It shows the voltage produced in a Galvanic half-cell.
What are galvanic cells used for?
Source of electrical energy, batteries
What are standard conditions under which standard electrode potentials are measured?
250C, 1 atm and 1M
What are the units for standard electrode potentials?
Volts (V)
What charge does the cathode have in an electrolytic cell?
The cathode has a negative charge in electrolytic cells
What does Eθ have to equal to be considered a spontaneous reaction?
Positive Value
What equation calculates the overall cell potential?
The cell potential is the difference between the reduction potentials: Eocell=Eored−Eooxid
What industrial situations use electrolytic cells?
Some examples of industrial situations in which electrolytic cells would be of use include metal plating and copper purifications.
What is a galvanic cell?
A cell in which spontaneous oxidation- reduction reactions produce electrical energy
What is an electrode?
A solid conductor of electricity
What is an electrolyte?
A solution that contains positive ions (cations) and negative ions (anions)
What is an external circuit in a Galvanic cell?
Wires that connect the anode to the cathode and allow the movement of electrons to occur
What is electrolysis?
The process by which electrical energy is passed into a cell to cause a non- spontaneous reaction to occur
What is oxidation?
Oxidation is the loss of electrons
What is the difference between cell potential and standard cell potential?
The cell potential is the measure of the potential difference between two half cells in an electrochemical cell.
What is the gain of electrons called?
Reduction
What is the job of the salt bridge in a Galvanic cell?
It is a connection between the 2 half cells that allows the movement of charged ions
What is the standard electrode potential of a half-cell a measure of?
This potential is a measure of the energy per unit charge which is available from the oxidation/reduction reactions to drive the reaction
What occurs at the anode?
Oxidation (Loss of electrons) occurs at the anode
What occurs at the cathode?
Reduction (gain of electrons) occurs at the cathode
What type of a reaction occurs in a Galvanic cell?
A spontaneous REDOX reaction
What type of chemical reaction occurs in a galvanic cell, Spontaneous, or non- spontaneous?
Spontaneous
What type of electrochemical cell contains a salt bridge?
Galvanic cell
What type of electrochemical cell uses energy from an external source?
Electrolytic cell
What type of electrode is needed for a molten electrolytic cell?
The electrode must be an inert material; have a higher melting point then the molten solution
What type of reaction occurs in electrolytic cells?
A forced non- spontaneous reaction.
Why does a Galvanic cell need to be separated into two half cells?
A forced non- spontaneous reaction.
Why does a Galvanic cell need to be separated into two half cells?
In order to utilise the current produced and start or stop the spontaenous reaction
Why is molten electrolysis rarely seen/used?
It requires a large amount of energy to both run the cell as well as to keep the solution molten.
