Specific heat capacity

The specific heat capacity (abbreviated C, also called specific heat) of a substance is defined as the amount of heat energy (measured in Joules) required to raise the temperature of one kilogram of the substance by one Kelvin. The SI unit for specific heat capacity is joule per kilogram per kelvin. Specific heat capacity is therefore heat capacity per unit mass. Heat capacity can be measured by using calorimetry.

The equivalent definition using cgs units is the amount of heat energy (measured in ergs) required to raise the temperature of one gram of the substance by one degree Celsius.

Approximation

Actually, this is only an approximation of heat capacity. An approximation is possible because measuring the slope (derivative) of the internal energy due to random motion of atoms in a sample as a function of temperature, normalized by dividing by the mass of the sample, is normally almost linear.

Factors that influence heat capacity measurements

• The temperature of the substance. For example, measuring the heat capacity of water produces different results if you start at 20 °C or 60 °C.
• Intermolecular forces. If a fluid has stronger intermolecular forces (such as hydrogen bonding in water) then the heat capacity is likely to be higher.

Table of specific heat capacities

Substance	Phase at 101.325 kPa (=1 atm), 20°C	ca. Specific heat capacity (J×g-1×°C-1)
Aluminum	solid	0.900
Gold	solid	0.129
Graphite	solid	0.720
Diamond	solid	0.502
Copper	solid	0.385
Brass	solid	0.377
Iron	solid	0.444
Mercury	liquid	0.139
Water	liquid	4.184
Ethanol	liquid	2.46

Related concepts

• specific melting heat
• specific heat of vaporization

See also

• Phase (matter)
• Changes of state by heat
• Latent heat

• Heat capacity temperature
• Volumetric heat capacity