Voltage
Definition and meaning of Voltage in chemistry.
Voltage, also known as electric potential difference, is the work required per unit of charge to move a test charge between two points in an electrical field. In electrochemistry, it is the driving force that pushes electrons through an external circuit connecting two half-cells.
In more detail
Voltage measures the tendency of a chemical reaction to proceed in a galvanic or voltaic cell, reflecting the difference in standard reduction potentials of the species involved. A positive voltage indicates a spontaneous redox reaction, meaning the cell can do electrical work. The Nernst equation allows chemists to calculate the voltage of a cell under non-standard conditions by accounting for the concentrations of the reactants and products. It is typically measured in volts (V) using a voltmeter.
Key facts
| Field | Analytical Chemistry |
|---|---|
| Unit | Volt (V) |
| Significance | Drives electron flow in redox reactions |
A standard alkaline AA battery provides a voltage of 1.5 V, which acts as the electromotive force driving electrons to power a small electronic device.
Frequently asked questions
What does a negative voltage mean for an electrochemical cell?
A negative voltage indicates that the reaction is non-spontaneous in the forward direction and requires an external power source to proceed, as in an electrolytic cell.