Specific Heat Capacity, Specific Heat At Constant Pressure and Constant Volume


A substance's heat capacity is definable by the amount required heat to approve the temperature of the amount given by the substance with units of temperature like degree-Celcius. Energy is needed to alter the capacity of a substance in terms of heat measurement.

The concept of the thermal properties is expressed to measure the heat capacity of an item in terms of measuring the relation between the Constant Volume (CV) and Constant Pressure (CP). In this tutorial, the relation between the CV and CP is expressed with the right properties that are relatable to the heat measurement.

An overview of specific heat capacity

Heat capacity is one of the vital factors that are taken as the fundamental perspective and the application of the heat capacity is practical including the traditional value.

The capacity of heat is measured using the parameters of temperatures. Mostly, the liquid heat capacities are extensive and extremely dependent on temperature. Between the 0.4 and 0.5 cal/g.k is referred to as the boiling point for the liquid organics. The heat capacity of water can be varied from 0°C to 350°C (Sciencedirect, 2022).

Figure 1: An overview of heat capacity

Measurement of specific heat capacity

Heat capacity can be estimated using the two essential properties, supplied energy (E) and temperature (T). The basic formula to measure the heat capacity is dividing the energy and temperature. Joules is taken as the SI unit for measuring the heat capacity. In general, the Heat Capacity is measured by the energy required per degree.

Energy Needed = Mass x Specific Heat x Temperature Change

(Pooley et al. 2020).

The units of Joules will follow the answer. The equation is

Heat Capacity = E / T

Heat capacity at Constant Volume (CV) and at Constant Pressure (CP)

Figure 2: Heat capacity at Constant Volume (CV) and a Constant Pressure (CP)

The capacity of heat is different for different objects with constant pressure and heat. Most of the time, heat is transferred depending on the type of substance. Unlike solid, gasses, or liquids are extreme when it comes to the capacity of heat.

The application of the heat can be constrained with the CV and CP and the application followed by. When the heat gets transferred at a constant volume, it is referred to as the isochoric process (Stepanov, 2020).

Whereas, when at a constant pressure, heat gets transferred, it is referred to as the isobaric process. Most of the time, the determined gas volume is maintained steady during healing. This causes the tension power of gas in the cylinder to advance during heating.


The gas to drive the piston against its significance did the process of measuring heat at different constants with the isobaric process work; no position was accomplished by or on the gas for the application of the isochoric process. Therefore, in the isobaric process, the transmitted heat energy is not completely employed to improve the kinetic power of the gas molecules. Part of the transmitted heat energy is transformed into work and is consequently not obtainable for supplementing the temperature (Biele et al. 2022). That portion of the heat energy leads to the accumulation of the kinetic energy of the molecules and accordingly to the accumulation in temperature advantages the so-called energy which is internally known as ΔU.

The process is mainly followed by the gas and makes the temperature cooling process with the reference of pressure-volume work. In order to convey the same modification in temperature, more heat needed to be delivered during isobaric heating to counteract the work accomplished in the procedure (Tec-science, 2022). Accordingly, the specific heat accommodation is continuously larger in the isobaric case corresponded to the isochoric process.

Relation between CV and CP

The compressible essences like gases are the constant with the power of CP and CV in the relevant to the substances that are relatable in the principle of pressure-volume work. In different cases, the solid and liquid substances are distinctive to obsolete. The low thermal multiplication is insignificant.

Figure 3: The specific capacity of Heat in the transformation of energy

The instruction q = n C ∆T denotes the heat q needed to obtain about a ∆T distinction in temperature of one mole of any consequence. The constant C here is named the molar heat capacity of the substant. Consequently, a substance's molar heat capacity is described as the amount of heat power demanded to transform the temperature of 1 mole by 1 unit in the substance. It counts on the essence, length, and manuscript of the procedure (Johnson, Martin & , 2020).

At the constant volume, the capacity of the molar heat C is characterised by CV and the constant pressure is represented with the character CP.


In this tutorial, the relationship between the constant volume and pressure has been defined for the definition of temperature which is expressed by mole. The capacity of the heat of any substance is determined by the transmission of heat with kinetic energy. An item's specific heat discloses how much energy is ought to increase by one unit which is usually 1 gram/degree.


Q1. Why does the Specific Heat of a Gas is relying on Constant Pressure?

CP is higher than CV due to the gas being heated at a constant volume. The increment of the internal energy of a gas is ready to be performed with the external pressure by the application of constant pressure.

Q2. What is Heat transfer?

A modification in the heat that directly corresponds to the alternation of the energy can improve the necessity to add the heat into the mass (m). Mass can influence the transformation of heat.

Q3. What happens during the isobaric process?

Since the gas volume is obvious in terms of changing throughout the isobaric process it is able to make the pressure constant to a stable quantity.



Biele, J., Grott, M., Zolensky, M. E., Benisek, A., & Dachs, E. (2022). The specific heat capacity of astro-material I: Review of theoretical concepts, materials and techniques. Retrieved from: https://www.researchsquare.com

Johnson, C. V., Martin, V. L., & Svesko, A. (2020). Microscopic description of thermodynamic volume in extended black hole thermodynamics. Physical Review D, 101(8), 086006. Retrieved from: https://link.aps.org

Pooley, L. I., Abu-Bakar, A. S., Cran, M. J., Wadhwani, R., & Moinuddin, K. A. (2020). Measurements of specific heat capacity of common building materials at elevated temperatures: a comparison of DSC and HDA. Journal of Thermal Analysis and Calorimetry, 141(4), 1279-1289. Retrieved from: https://vuir.vu.edu.au

Stepanov, I. A. (2020). Determination of the isobaric heat capacity of gases heated by compression using the Clément-Desormes method. J. Chem. Biol. Phys. Sci. Section C, 10, 108-116. Retrieved from: https://www.researchgate.net


Geeksforgeeks, (2022), About Heat capacity, Retrieved from: https://www.geeksforgeeks.org/heat-capacity/ [Retrieved on 16th June 2022]

Sciencedirect, (2022), About Heat capacity, Retrieved from: https://www.sciencedirect.com [Retrieved on 16th June 2022]

Tec-science, (2022), About Heat capacity at Constant Volume (CV) and at a Constant Pressure (CP), Retrieved from: https://www.tec-science.com [Retrieved on 16th June 2022]


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Updated on: 13-Oct-2022


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