IB Docs (2) Team MC test: Electrochemical cells
Multiple choice test on 9.2 Electrochemical cells
Use the following 'quiz' to test your knowledge and understanding of this sub-topic. You will need access to a periodic table (Section 6 of the IB data booklet).
If you get an answer wrong, read through the explanation carefully to learn from your mistakes.
Which are correct statements about voltaic (also known as Galvanic) cells?
I. Electricity is produced as the result of spontaneous exothermic chemical reactions.
II. Oxidation occurs at the cathode (positive electrode).
III. When the cell is operating electrons flow through the external circuit in a simple cell from the more reactive metal to the least reactive metal.
Oxidation occurs at the negative electrode (anode) as the reactive metal is losing electrons which can then flow through the external circuit. Oxidation always occurs at the anode.
Which are correct statements about electrolytic cells?
I. Electrical energy is converted into chemical energy to bring about spontaneous chemical reactions.
II. Oxidation occurs at the anode (positive electrode).
III. Electrons flow from the negative terminal on the battery to the cathode in the external circuit.
The whole reason for the external source of electricity is to provide the energy to bring about a non-spontaneous chemical reaction.
Which statement explains how the electric current is conducted through the electrolyte in electrolytic cells.
There are no salt bridges in electrolytic cells. Electricity is conducted by the movement of ions through the electrolyte.
The diagram shows a zinc-copper voltaic cell.
Which statement is not correct when the cell is operating?
The half-equation for the reaction at the anode (negative electrode) is Zn(s) → Zn2+(aq) + 2e− so [Zn2+(aq)] will be increasing while the cell is operating.
Which will undergo electrolysis to produce bromine?
Only BaBr2 and MgBr2 are ionic but the salt needs to be in the liquid state (i.e. molten) so the ions are free to move before it can be electrolysed.
Magnesium is above nickel in the activity series.
What must be true about a cell made from a nickel half-cell and a magnesium half-cell when it is operating.
For any voltaic cell to do work the overall chemical reaction taking place must be exothermic and spontaneous.
Which is the conventional way to depict a cell made from a zinc half-cell connected to a copper half-cell?
It is conventional to describe the anode half-cell before the cathode half-cell. When you read it, your eyes move in the direction of electron flow. A slash (or single vertical line) is drawn between two chemical species that are in different phases but in physical contact with each other. A double vertical line represents the salt bridge separating the individual half-cells.
Which is the correct half-equation for the reaction taking place at the cathode during the electrolysis of molten lithium chloride?
The cathode is the negative electrode in an electrolytic cell where reduction occurs to form lithium metal.
Which is the correct half-equation for the reaction taking place at the cathode during the operation of a cell constructed from a zinc half-cell connected to a copper half-cell?
The cathode is the positive electrode in a voltaic cell where reduction occurs so copper(II) ions are reduced to copper.
Which row contains the correct descriptions of the polarity of the electrodes?
| Electrolytic | cell | Voltaic | cell | |
| Row | Anode | Cathode | Anode | Cathode |
| 1 | positive | negative | positive | negative |
| 2 | positive | negative | negative | positive |
| 3 | negative | positive | negative | positive |
| 4 | negative | positive | positive | negative |
The anode is always where oxidation occurs. This is at the positive electrode in an electrolytic cell and the negative electrode in a voltaic cell.
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