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In simple terms, heat capacity is the amount of heat that is required to raise the temperature of a material or object by Celsius. A measurable quantity measures the amount of heat required to change the temperature by any degree Celsius. Heat capacity is measured in Joules per kelvin. Since it is an extensive property, heat capacity scales alongside the size of the system.
This article will discuss heat capacity, its definition, internal energy, types of heat capacity, the effect of heat, and the difference between the three types of heat capacities.
What is heat?
Heat is an energy form that can flow from one system to another. To understand the transfer of energy as heat more effectively, one can consider the example of boiling water. When one paces a bowl of water on the stove, the bowl will get heated up first, after which the water will start getting heated up.
Once the water becomes warmer, it will start boiling after a while. The pattern at which the heat will flow depends directly on the temperature of the water and bowl. The temperature of a body determines the direction of heat flow and whether the body is considered hot or cold.
Definition of heat capacity
Heat capacity is the heat energy required to raise the temperature to a specific limit. It is an innate property of a substance. For example, a substance having the highest heat capacity is water, with a heat capacity of 4184 J per kilogram. This means that it requires 4184 J of heat energy to raise water’s temperature by 1 kelvin.
Internal energy
In simple words, internal energy is the sum of the potential and kinetic energies of the molecules that constitute a system. Since molecules display chaotic and random motion, it gives rise to internal energy within the system. The internal energy of any system depends severely on the temperature. The more molecular motion seen in the system, the higher the internal energy will be, and the temperature will increase.
Types of Heat capacity
Specific heat capacity
It is the amount of heat required to increase the temperature of 1 gram of a substance by a degree Celsius. There won’t be any change in the specific heat capacity for more oversized objects as it is only applicable for a gram of substance. The unit to measure and calculate specific heat capacity is Joules per gram per degree Celsius. It depends on the mass of the substance involved.
Molar heat capacity
The amount of heat required to increase the temperature of 1 mole of a substance by a degree Celsius is known as molar heat capacity. The units to measure and calculate molar heat capacity are Joules per mol per degree Celsius. Therefore, it depends on the total number of moles of the substance involved.
Effect of Heat
Heat has a unique effect on solids regarding the dimension of the objects. Therefore, an increase in temperature in solids and an increase in dimension give rise to the theory of thermal expansion.
Linear expansion or expansion of the length of any object is the first kind of thermal expansion. The expansion of the area of any object is known as area expansion or superficial expansion. Last but not least, the expansion in the volume of any object is known as volume expansion.
Conclusion
Heat capacities allow people to study the change in temperature of a substance after it experiences a certain amount of heat. It is most popularly used in calorimetry. Heat capacity, in simple terms, is the amount of heat that an object or substance will require to increase its temperature by a degree Celsius. It is measured in Joules per kelvin. The heat capacity depends on the pressure, temperature and even the volume of the substance system involved. Therefore, it is an extensive property and it scales with the dimensions of the system. In the world of thermodynamics, heat capacity is a measurable physical quantity. The heat capacity of substances differs from one substance to the other and water is known to have a high heat capacity value compared to other substances.
