What is Specific Heat?
The specific heat of a substance also sometimes referred to as massic heat capacity is the amount of heat that must be added to one unit of mass of the substance in order to cause an increase of one unit in temperature. The SI unit of specific heat capacity is joule per kelvin per kilogram, J⋅kg−1⋅K−1.
Specific heat values can be determined in the following way: When two materials, each initially at a different temperature, are placed in contact with one another, heat always flows from the warmer material into the colder material until both the materials attain the same temperature. From the law of conservation of energy, the heat gained by the initially colder material must equal the heat lost by the initially warmer material.
Specific heat is an intensive property as it is independent of the quantity or size of the matter. Mathematically it is given as:
Q= m c ΔT
Here Q is the amount of heat energy required to change the temperature of m (kg) of a substance by ΔT, s is the specific heat capacity of the system.
The term specific heat may also refer to the ratio between the specific heat capacities of a substance at a given temperature and of a reference substance at a reference temperature, such as water at 15 °C; much in the fashion of specific gravity.
What is Heat Capacity?
Heat capacity or thermal capacity is a physical property of matter, defined as the amount of heat to be supplied to an object to produce a unit change in its temperature. In other words, it is the amount of heat required to raise the temperature of an object by 1°C.
Heat capacities are measured with some variety of calorimeter, and, using the formulation of the third law of thermodynamics, heat-capacity measurements became important as a means of determining the entropies of various materials.
Heat capacity for a given matter depends on its size or quantity and hence it is an extensive property. The unit of heat capacity is joule per Kelvin or joule per degree Celsius.
Mathematically,
Q=CΔT
Where Q is the heat energy required to bring about a temperature change of ΔT and C is the heat capacity of the system under study.
Specific Heat vs Heat Capacity: Key Differences
| Specific Heat | Heat Capacity |
| The specific heat of a substance is the amount of energy required to raise the temperature of 1 gram of the substance by 1°C. | Heat capacity is the amount of heat required to raise the temperature of an object by 1°C. |
| Specific heat does not depend on the mass of an object, as it is defined per unit mass. | Heat capacity is directly proportional to the mass of an object. |
| The SI unit of specific heat is Joule per kilogram per Kelvin (J Kg⎺1 K⎺1) or Joule per kilogram per degree Celsius (J Kg⎺1 ℃⎺1). | The SI unit of heat capacity is Joule per Kelvin (J K⎺1) or Joule per degree (J ℃⎺1). |
| The formula of “Specific Heat energy (c) = Q/m∆T; Where ‘Q’ is the amount of heat; ‘∆T’specific refers to the temperature; ‘m’ stands for mass. | The formula of “Heat energy” = Q/∆T ; Where ‘Q’ is the amount of heat. ‘∆T’ specifically refers to the temperature. |
| Specific heat is denoted by c. | Heat capacity is denoted by C. |
Key Takeaways
- Heat capacity is the amount of heat required to raise the temperature of an object by 1°C.
- The specific heat of a substance is the amount of energy required to raise the temperature of 1 gram of the substance by 1°C.
- Heat capacity is directly proportional to the mass of an object. Specific heat does not depend on the mass of an object, as it is defined per unit mass.
- The SI unit of specific heat is Joule per kilogram per Kelvin (J Kg⎺1 K⎺1) or Joule per kilogram per degree Celsius (J Kg⎺1 ℃⎺1). Whereas the SI unit of heat capacity is Joule per Kelvin (J K⎺1) or Joule per degree (J ℃⎺1).
- The formula of specific heat is Q = mc T, on the other hand, the formula to calculate heat capacity is C = Q/ T.
- Specific heat is denoted by c, on the other hand, heat capacity is denoted by C.