What Is Specific Volume?

The volume occupied by a substance of unit mass is called the specific volume, which is represented by the symbol "V". Its value is the inverse of density, that is, V = 1 / . Specific volume is used in atmospheric science a lot, and it can be applied to the definition of potential vorticity.

Specific volume (English: specific volume, {\ displaystyle \ nu}) is a unit

The concepts of specific volume and specific volume are exactly the same. Suggest a merger. The volume occupied by a substance of unit mass is called the specific volume, which is represented by the symbol "V". Its value is the inverse of density. That is to say, V = 1 / specific volume is widely used in atmospheric science, and can be applied to the definition of potential vorticity. Due to the high temperature and low salinity in the equatorial area, the density of surface seawater is very small, about 1.023; although the salinity in the subtropical sea area is high, but the temperature is also high, the density is still not large; due to the very high temperature in the polar sea area Low, so it has the highest density. In the vertical direction, the structure of seawater is always stable, and the density is increasing downward. The vertical gradient of density in the upper layer of the ocean is large, starting from about 1500 meters. The vertical gradient of density is very small. In the deep layer, the density hardly changes with depth. The heat of vaporization of water is 40.8 kJ / mol, which is equivalent to 2260 kJ / kg.

The volume occupied by a substance of unit mass is called the specific volume, which is represented by the symbol "V". Its value is the inverse of density.

Seawater specific volume

Seawater density is the mass contained in a unit volume of seawater.

Seawater specific volume refers to the volume occupied by seawater per unit mass, which is the inverse of density in value.

specific volume

The density of seawater changes with temperature and salinity. Therefore, various factors affecting temperature and salinity will affect the distribution and change of seawater density. In the horizontal direction, the ocean surface density increases with increasing latitude, and the contour line is approximately parallel to the latitude. Due to the high temperature and low salinity in the equatorial area, the density of surface seawater is very small, about 1.023; although the salinity in the subtropical sea area is high, but the temperature is also high, the density is still not large; due to the very high temperature in the polar sea area Low, so it has the highest density. In the vertical direction, the structure of seawater is always stable, and the density is increasing downward. The vertical gradient of density in the upper layer of the ocean is large, starting from about 1500 meters. The vertical gradient of density is very small. In the deep layer, the density hardly changes with depth.

Hematocrit (Hct, Ht) (specific volume / hematocrit)

Hematocrit, also called hematocrit, refers to the volume percentage of blood cells in the blood. Normal adult males are 40% to 50%, and females are 37% to 48%. It reflects changes in the relative number of red blood cells and plasma in the blood. The hematocrit is the volume ratio. When there is less plasma, the specific volume is higher, and when there is more plasma, the specific volume is reduced. In addition, the more red blood cells are destroyed, the lower the specific volume will be.

Specific volume of steam

The amount of heat absorbed by a substance with a temperature increase of 1 ° C per unit mass is called the specific heat capacity of the substance, referred to as specific heat

Look at the pressure. If you ignore the change in pressure, it is the same as the specific heat of water. The specific heat capacity of 4.2 * 10joule / kg steam is 2.1 * 10joule / kg · ° C. The heat of vaporization is a physical property of a substance. It is defined as the heat required to evaporate a mole of a substance at its boiling point under standard atmospheric pressure (101.325 kPa). Commonly used units are kilojoules / mole (also known as kilojoules / mole), kilojoules / kilogram is also used. Other units still in use include Btu / lb (British units, Btu is British Thermal Unit, lb is Pound). The heat of vaporization of water is 40.8 kJ / mol, which is equivalent to 2260 kJ / kg. In general: the amount of heat required to evaporate water at its boiling point is five times the amount of heat required to heat an equivalent amount of water from one degree Celsius to one hundred degrees Celsius ^[1] .

Example

1. Seawater specific volume

Seawater density is the mass contained in a unit volume of seawater.

Seawater specific volume refers to the volume occupied by seawater per unit mass, which is the inverse of density in value.

The density of seawater changes with temperature and salinity. Therefore, various factors affecting temperature and salinity will affect the distribution and change of seawater density. In the horizontal direction, the ocean surface density increases with increasing latitude, and the contour line is approximately parallel to the latitude. Due to the high temperature and low salinity in the equatorial area, the density of surface seawater is very small, about 1.023; although the salinity in the subtropical sea area is high, but the temperature is also high, the density is still not large; Low, so it has the highest density. In the vertical direction, the structure of seawater is always stable, and the density is increasing downward. The vertical gradient of density in the upper layer of the ocean is large, starting from about 1500 meters. The vertical gradient of density is very small. In the deep layer, the density hardly changes with depth.

2. Hematocrit (Hct, Ht) (specific volume / hematocrit)

Hematocrit, also called hematocrit, refers to the volume percentage of blood cells in the blood. Normal adult males are 40% to 50%, and females are 37% to 48%. It reflects changes in the relative number of red blood cells and plasma in the blood. The hematocrit is the volume ratio. When there is less plasma, the specific volume is higher. When there is more plasma, the specific volume is decreased. In addition, the destruction of red blood cells increases, and the specific volume also decreases.

Clinical significance:

The clinical significance of hematocrit measurement is basically the same as red blood cell count or hemoglobin measurement. It is often used as an indicator for the diagnosis and classification of anemia. It can also be used as a clinical test basis for determining whether a patient needs fluid replacement.

Increased hematocrit is seen in normal people with strenuous exercise or emotional excitement, and patients with various dehydration symptoms such as large-scale burns

Decreased hematocrit seen in normal pregnant women with various anemia patients and the use of interferon penicillin indimemetine (indomethacin) vitamin A and other drugs

Specific volume is the opposite of density. Density is the mass of a substance per unit volume (solid is called volume). The unit is Kg / m3. Specific volume is the volume of a substance per unit mass. The unit is m3 / kg.

3. Specific volume of soil

Represents a special volume, which means that when the volume of solid particles is assumed to be 1, the volume of the void is e, and the total volume, that is, the specific volume is equal to the sum of the solid particles and the volume of the void 1 + e

3. Capacitance density (Cp)

Cp refers to the capacitance formed per unit effective area of the electrode. Its expression is:

Cp = C / S