The specific heat capacity of a material is the amount of heat energy needed to heat 1 kg of the material by 1° Celsius. The table presented below, presents the specific heat capacity of some metals at constant pressure (c p ) at a temperature of 25° Celsius.
|
Metal Element |
Specific Heat Capacity at Constant Pressure (25° Celsius) J / g K |
|
Aluminum |
0.897 |
|
Antimony |
0.207 |
|
Bismuth |
0.123 |
|
Cadmium |
0.231 |
|
Chromium |
0.449 |
|
Copper |
0.385 |
|
Gold |
0.129 |
|
Iron |
0.450 |
|
Lead |
0.129 |
|
Mercury |
0.1395 |
|
Magnesium |
1.02 |
|
Silver |
0.233 |
|
Tin |
0.227 |
|
Zinc |
0.387 |
|
Tungsten |
0.134 |
Specific Heat Capacities of Certain Compounds
The specific heat capacities of a selection of compounds is shown below. They are much higher than the metals.
|
Compound/Mixture |
Specific Heat Capacity at Constant Pressure (25° Celsius) J/g K |
|
Air at 0° Celsius |
1.0035 |
|
Ammonia |
4.700 |
|
Hydrogen Sulfide |
1.015 |
|
Methane at 2° Celsius |
2.191 |
|
Paraffin Wax |
2.5 |
|
Solid Polyethylene |
2.3027 |
|
Ice (-10° Celsius) |
2.11 |
|
Water (25° Celsius) |
4.1813 |
|
Ethyl Alcohol at 20° Celsius |
2.4 |
The reason is that when a metal is heated, most of the heat energy is used to increase the kinetic energy of the free electrons. Very little is used to increase the vibrational kinetic energy of the atoms in the lattice. The electrons are much less heavy than the atoms and are easily heated. In contrast, the atoms in the compounds in the table above have no free electrons, so any energy is used to increase the energy of the atoms. It takes much more energy to do this, so the specific heat capacity is much higher.