9.4 Electrochemical Cells Flashcards
What are the two types of electrochemical cells?
Voltaic (galvanic) cells and electrolytical cells.
What is electrolysis?
The break-in down of a substance in molten state or solution by the passage of electricity through it.
What is the anode?
Electrode at which oxidation occurs.
What is the cathode?
Electrode at which reduction occurs.
What is the overall reaction in a voltaic cel?
Zn (s) + Cu2+ (aq) —–> Zn2+ (aq) + Cu (s)
What is the cell convention of a voltaic cell?
Zn(s) | Zn2+(aq) || Cu2+(aq) | Cu(s)
How does a voltaic cells convert energy?
Converts chemical energy from a spontaneous exothermic process to electrical energy.
What is the anode and cathode in a voltaic cell?
Anode is NEGATIVE and cathode is POSITIVE.
What happens to the more reactive metal in a voltaic cell?
It is always oxidised at the anode.
How do the electrons flow in a voltaic cell?
Electrons flow from the more reactive metal through the external circuit to the ion of the less reactive metal. Electrons flow from the anode to the cathode.
What happens at the cathode in a voltaic cell?
The ion of the less reactive metal is reduced at the cathode.
Why is a salt bridge necessary in a voltaic cell?
The salt bridge completes the circuit and allows ions to flow into and out of the half cell. Ions move in the solution and the salt bridge.
What can the salt bridge be made from?
A piece of paper soaked in a solution of an ionic salt such as KCl (aq).
What determines the voltage in a voltaic cell?
The bigger the difference in reactivity between the metals the bigger the voltage.
What is the overall reaction in a electrolytic cell?
PbBr2 (l) ——> Pb (l) + Br2 (g)
How is energy converted in an electrolytic cell?
Converts electrical energy to chemical energy by forcing a non spontaneous reaction to occur.
What is the anode and cathode in an electrolytic cell?
Anode is POSITIVE and cathode is NEGATIVE.
What is oxidised at the anode in an electrolytic cell?
The negative ion is oxidised at the anode.
How do the electrons flow in an electrolytic cell?
Electrons flow from the battery to the negative electrode (cathode) and from the positive electrode (anode) to the battery.
What is reduced at the cathode in an electrolytic cell?
The positive ions is reduced at the cathode.
How do ions move in an electrolytic cell?
Ions move in the electrolyte and electrons flow in the external circuit.
How can electricity flow in the electrolytic cell?
The salt must be molten for electricity fro flow when molten the ions are free to move if it is sold then ions are not free to move.
What are the products of electrolysis of a molten salt?
The elements which is it made up of.
What does the cell convention for voltaic cells show?
It describes the overall reaction, a single line represent a phase boundary and the delve line is the salt bridge. The reaction at the anode is shown on the left (oxidation) and the reaction at the cathode (reduction) on the right.
