Final answer:
A voltaic cell, also known as a galvanic cell, is an electrochemical cell that converts chemical energy into electrical energy through spontaneous oxidation-reduction reactions.
Step-by-step explanation:
The correct answer to the student's question about voltaic cells is a: electrochemical cells in which spontaneous oxidation-reduction reactions convert chemical energy to electrical energy. A voltaic cell, which is often referred to as a galvanic cell, harnesses the energy released by a spontaneous redox reaction to produce electricity. In these cells, the oxidation process and the reduction process occur as separate half-reactions, potentially in different compartments that are connected by both an external circuit that allows the electrons to flow and a salt bridge that maintains electrical neutrality. The flow of electrons from the oxidation half-reaction to the reduction half-reaction generates an electric current, which is utilized to power electrical devices.
To summarize how a voltaic cell works: in the compartments of the cell, the anode is the electrode where the oxidation half-reaction occurs, and the cathode is where the reduction half-reaction happens. The resulting potential difference, or voltage, between these electrodes causes electrons to flow, thereby creating electrical energy from the spontaneous chemical reaction that occurs.