What units are used for molar heat capacity?

Molar heat capacity is defined as the amount of heat required to raise the temperature of one mole of a substance by one degree Kelvin (or Celsius). The units reflect this requirement, which is why the correct answer features "J K⁻¹ mol⁻¹."

Breaking down these units: "J" stands for joules, the unit of energy; "K" represents Kelvin, the unit of temperature; and "mol" indicates the number of moles. Therefore, when you express molar heat capacity, you are essentially measuring how many joules of energy are needed to increase the temperature of one mole of the substance by one Kelvin.

Other options provided do not accurately convey this relationship. For instance, units like J K⁻¹ g⁻¹ would denote heat capacity per gram, which is not reflective of the molar concept. "kJ K⁻¹" represents kilojoules per Kelvin without taking into account the amount of substance (in moles), while "kJ mol⁻¹" refers to energy per mole without the temperature change context. Hence, the choice of J K⁻¹ mol⁻¹ correctly captures both the magnitude of heat energy required and its dependence on the molar