Final answer:
The term that describes the rate at which energy is expended or enthalpy changes is wattage, which is power expressed in watts. The concept applies to scenarios including the dissipation of thermal energy in resistors and the charging of batteries.
Step-by-step explanation:
The term used to describe the rate at which enthalpy or energy is expended is wattage. This is because wattage is the unit of power in the International System of Units (SI), and it quantifies the rate of energy transfer. In electric circuits, when a resistor dissipates energy, it does so in the form of heat. Regarding the car battery scenario, potential difference across the terminals while charging would take into account the internal resistance and the charging current. The rate at which thermal energy is being dissipated in the battery can be found using the formula P = I²R, and the rate at which electric energy is being converted to chemical energy can be calculated as the product of the current and the emf of the battery.