Specific heat refers to the total amount of heat energy needed by one unit of any substance to increase its temperature by 1°C.
On the other hand, thermal conductivity is the ability of a given material to transfer or conduct heat energy through it.
Key Takeaways
- Specific heat measures a material’s capacity to store thermal energy, while thermal conductivity describes how well a material conducts heat.
- A substance with high specific heat can absorb more heat without experiencing a significant temperature change, whereas a material with high thermal conductivity transfers heats rapidly.
- Different applications require different combinations of specific heat and thermal conductivity, depending on factors like insulation, heat exchange, and temperature stability.
Specific Heat vs Thermal Conductivity
Specific Heat is the amount of heat energy required to raise the temperature of a unit mass of a substance by one degree Celsius or Kelvin. Thermal Conductivity is the ability of a material to conduct heat and is a measure of how quickly heat can pass through a material from one point to another.
Specific heat is measured in calories or joules per gram per degree Celsius. Occasionally, the ratio of specific heat capacities of a substance at a particular temperature to those of a reference substance at a reference temperature is also termed specific heat. The formula to calculate specific heat is:
c = ΔQmΔT
where
c refers to the specific heat of a substance
ΔQ refers to the heat gained or lost by the substance,
m refers to the mass of the substance, and
ΔT refers to the change in temperature of the substance.
Thermal conductivity is one of the three processes of heat transfer—convection, conduction, and radiation. Its unit is Watts per meter Kelvin. Thermal conductivity depends on some factors, such as temperature, moisture content, and density of a material.
K = (QL)/(AΔT)
where
K refers to the thermal conductivity (W/m.K),
Q refers to the heat amount transferred across a material (Joules/second or Watts),
L refers to the distance between two isothermal planes,
A refers to the surface area (square meters), and
ΔT refers to the temperature difference (Kelvin).
Comparison Table
| Parameters of Comparison | Specific Heat | Thermal Conductivity |
|---|---|---|
| Definition | Specific heat refers to the total amount of heat energy that is needed by one unit of any substance to increase its temperature by 1°C. | Thermal conductivity refers to the given material’s ability to transfer heat energy across it. |
| Symbol | Specific heat is denoted as cp or s. | Thermal conductivity is denoted by K. |
| Units | Specific heat is measured in calories or joules per gram per degree Celsius or Kelvin (J/(kg K) or J/(kg °C)). | The unit for thermal conductivity is watts per metre-kelvin (W/(m⋅K)). |
| Formula | c = ΔQmΔT | K = (QL)/(AΔT) |
| Influencing factors | Specific heat depends on the type and the phase of a substance. | Thermal conductivity primarily depends on the temperature and the heat transfer direction. |
| Experimental values for some compounds | The specific heat of water is 4,186 joules per kilogram per degree Celsius whereas that of wood is 1,700 joules per kilogram per degree Celsius. | The thermal conductivity of water at 0°C is 0.5610 W/(m K) whereas that of wood is 0.12–0.04 W/(m k). |
| Applications | Substances that have low specific heat capacities are used in cookware like kettles and frying pans. | High thermal conductivity materials are used in heat sink applications, whereas low thermal conductivity materials are used as thermal insulators. |
What is Specific Heat?
Specific heat is also known as the massic heat capacity. It may also refer to the ratio of specific heat capacities of a substance at any given temperature to those of a reference substance at a reference temperature.
It has been demonstrated that specific heats of substances allow the calculation of the atomic weights of compounds.
Specific heat values are always dependent on the phase and properties of a substance, and they are measured empirically and available for reference.
Substances that have a low specific heat capacity are used in cookware like kettles, pots, frying pans, and so on; this is due to the fact that when a small amount of heat is applied, these substances will get heated quickly.
Specific heat is used in the construction of handles (cooker and kettle handles), insulators, and oven covers also; because only a small temperature change is observed even after high heat exposure.
What is Thermal Conductivity?
Thermal conductivity occurs by molecular agitation within a given substance. That is, heat energy is transported due to random molecular motion.
Materials such as aluminium, copper, and silver have high thermal conductivity and good thermal conductivity.
Materials such as wood, alumina, polyurethane, and polystyrene have low thermal conductivities.
Such materials are thermal insulators.
The thermal conductivity of a substance varies when the substance changes from one phase to another. For example, the thermal conductivity of ice changes when it melts into water.
Main Differences Between Specific Heat and Thermal Conductivity
- Specific heat refers to the heat retained in a system, whereas thermal conductivity refers to the heat transfer within a system or between different systems.
- Thermal conductivity is expressed by the symbol ‘k’, but it can also be denoted by ‘λ’ and ‘κ’. Specific heat is denoted as c or s.
- Specific heat depends on the type and phase of a material under study, whereas thermal conductivity depends on the temperature, moisture content, and density of a material.
- Specific heat is measured using the mass, the change in temperature, and the heat gained or lost by a substance. Thermal conductivity is measured using the difference in temperature, the amount of heat transferred through the material, the distance between the planes, and the surface area.
- Specific heat is the ability of a unit of a compound to hold a particular amount of heat energy. Thermal conductivity is the potential of a substance to transfer heat energy.
- https://journals.aps.org/prb/abstract/10.1103/PhysRevB.4.2029
- https://aip.scitation.org/doi/abs/10.1063/1.3253100
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