The key difference between volume and specific volume is that volume is an extensive property whereas specific volume is an intensive property. Volume is a thermodynamic state of a substance. Specific volume is a chemical concept that represents the relationship between mass and volume of a substance.
The physical properties of a substance are in two main types of intensive properties and extensive properties. Intensive properties are those that do not depend on the size of a thermodynamic system. Extensive properties are those that do depend on the size of a thermodynamic system.
CONTENTS
1. Overview and Key Difference
2. What is Volume
3. What is Specific Volume
4. Side by Side Comparison – Volume vs Specific Volume in Tabular Form
5. Summary
What is Volume?
Volume is a thermodynamic state of substances that refers to the volume of working fluid of a thermodynamic system. It is an extensive property. This means this parameter depends on the temperature and pressure of the thermodynamic system. The changes of this volume are useful in producing a work.
Figure 01: Volumetric Flasks are Useful to Measure the Volume of Liquids
The volume of an ideal gas is directly proportional to the temperature of the gas and is inversely proportional to the pressure.
PV = nRT
Where P is pressure, V is volume, n is the number of moles of gas, R is the universal gas constant and T is the temperature of the gas. Then the volume of the ideal gas is as follows:
V = nRT /P
What is Specific Volume?
Specific volume is the volume of a unit mass of a substance. In other words, it is the ratio of a substance’s volume to its mass. It is an intensive property of a substance and the reciprocal of the density. the unit of measurement is (m3/kg). The equation for the specific volume is as follows:
ν = V / m
ν is the specific volume, V is the measured volume and m is the mass of a substance. We can obtain the specific volume of an ideal gas using the following steps:
PV = nRT
PV = (m/M)RT
Then, P (V/m) = (1/M)RT
ν = RT/PM
What is the Difference Between Volume and Specific Volume?
Volume is a thermodynamic state of substances that refers to the volume of working fluid of a thermodynamic system. Specific volume is the volume of a unit mass of a substance. Therefore, the unit of measurement for volume is m3 and the unit of measurement of specific volume is m3/kg.
Furthermore, the equation for the volume of an ideal gas is V = nRT /P while the equation for the specific volume of an ideal gas is ν = RT/PM. With regard to the nature of these two properties, volume is an extensive property. However, specific volume is an intensive property.
Summary – Volume vs Specific Volume
Volume is a thermodynamic property of a substance. Specific volume is the volume of a unit mass of a substance. The difference between volume and specific volume is that volume is an extensive property whereas specific volume is an intensive property.
Reference:
1. “Volume (Thermodynamics).” Wikipedia, Wikimedia Foundation, 23 May 2018. Available here
2. “What Is Specific Volume? – Definition from WhatIs.com.” WhatIs.com. Available here
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1.’860478′ by schlayphe (CC0) via pixabay