Final answer:
The units of molar heat capacity are J/(mol°C) or J/(mol·K), which indicate the heat energy required to raise the temperature of one mole of a substance by one degree. To calculate it for a metal, multiply its specific heat capacity by its molar mass.
Step-by-step explanation:
The units of molar heat capacity are expressed as joules per mole per degree Celsius (J/(mol°C)) or joules per mole per kelvin (J/(mol·K)). This represents the amount of heat energy (in joules) required to raise the temperature of one mole of a substance by one degree Celsius or one kelvin. The specific heat capacity (cs) requires units of J/(g°C), whereas the molar heat capacity involves the molar mass of the substance and thus relates to mols, not grams.
To calculate the molar heat capacity of a metal like aluminum, you multiply the specific heat capacity by the metal's molar mass. If we consider aluminum's specific heat capacity (cs = 0.900 J/(g°C)) and its molar mass, we get the molar heat capacity for aluminum. Moreover, for different temperatures and conditions, such as constant volume or constant pressure, the molar heat capacity can change as exhibited by gases like hydrogen where molar heat capacity varies with temperature.