Specific Heat Capacity Definition
Specific heat capacity is the amount of heat energy required to raise the temperature of a substance per unit of mass. The specific heat capacity of a material is a physical property. It is also an example of an extensive property since its value is proportional to the size of the system being examined.
Key Takeaways: Specific Heat Capacity
- Specific heat capacity is the quantity of heat needed to raise the temperature per unit mass.
- Usually, it's the heat in Joules needed to raise the temperature of 1 gram of sample 1 Kelvin or 1 degree Celsius.
- Water has an extremely high specific heat capacity, which makes it good for temperature regulation.
In SI units, specific heat capacity (symbol: c) is the amount of heat in joules required to raise 1 gram of a substance 1 Kelvin. It may also be expressed as J/kg·K. Specific heat capacity may be reported in the units of calories per gram degree Celsius, too. Related values are molar heat capacity, expressed in J/mol·K, and volumetric heat capacity, given in J/m3·K.
Heat capacity is defined as the ratio of the amount of energy transferred to a material and the change in temperature that is produced:
C = Q / ΔT
where C is heat capacity, Q is energy (usually expressed in joules), and ΔT is the change in temperature (usually in degrees Celsius or in Kelvin). Alternatively, the equation may be written:
Q = CmΔT
Specific heat and heat capacity are related by mass:
C = m * S
Where C is heat capacity, m is mass of a material, and S is specific heat. Note that since specific heat is per unit mass, its value does not change, no matter the size of the sample. So, the specific heat of a gallon of water is the same as the specific heat of a drop of water.
It's important to note the relationship between added heat, specific heat, mass, and temperature change does not apply during a phase change. The reason for this is because heat that is added or removed in a phase change does not alter the temperature.
Also Known As: specific heat, mass specific heat, thermal capacity
Specific Heat Capacity Examples
Water has a specific heat capacity of 4.18 J (or 1 calorie/gram °C). This is a much higher value than that of most other substances, which makes water exceptionally good at regulating temperature. In contrast, copper has a specific heat capacity of 0.39 J.
Table of Common Specific Heats and Heat Capacities
This chart of specific heat and heat capacity values should help you get a better sense of the types of materials that readily conduct heat versus those which do not. As you might expect, metals have relatively low specific heats.
Material | Specific Heat (J/g°C) |
Heat Capacity (J/°C for 100 g) |
gold | 0.129 | 12.9 |
mercury | 0.140 | 14.0 |
copper | 0.385 | 38.5 |
iron | 0.450 | 45.0 |
salt (Nacl) | 0.864 | 86.4 |
aluminum | 0.902 | 90.2 |
air | 1.01 | 101 |
ice | 2.03 | 203 |
water | 4.179 | 417.9 |
Sources
- Halliday, David; Resnick, Robert (2013). Fundamentals of Physics. Wiley. p. 524.
- Kittel, Charles (2005). Introduction to Solid State Physics (8th Ed.). Hoboken, New Jersey, USA: John Wiley & Sons. p. 141. ISBN 0-471-41526-X.
- Laider, Keith J. (1993). The World of Physical Chemistry. Oxford University Press. ISBN 0-19-855919-4.
- unus A. Cengel and Michael A. Boles (2010). Thermodynamics: An Engineering Approach (7th Edition). McGraw-Hill. ISBN 007-352932-X.