Molar volume is a concept used in the field of chemistry. The notion is used to name the volume occupied by one mole of a substance, using the cubic meter per mole as the reference unit.
As you can see if we analyze the definition that we mentioned in the first paragraph, to understand what is the molar volume, it is essential to understand what is the volume and what is a mole. The notion of molar volume is used in chemistry. Analyzing the concepts of volume and mole The idea of volume can be used in different ways: in this case, we are interested in its meaning as the magnitude that indicates the space occupied by something in height, width and length (that is, in three dimensions) . A mole, in turn, is a unit that allows us to measure the amount of an element that has a weight equivalent to its molecular weight reflected in grams.
It is important to mention that, in any substance, a mole contains an amount of mass that is contained in 6.022 x 10 raised to 23 molecules. This value (6.022 x 10 raised to the power of 23) is called Avogadro’s number and is the number of atoms in twelve grams of pure carbon-12. Avogadro’s number allows microscopic entities to be counted from microscopic measurements. It is also necessary to know Avogadro’s law, which indicates that when different gases are measured under identical conditions of temperature and pressure, they contain the same number of particles. What is the molar volume Returning to the idea of molar volume, from what is mentioned by Avogadro’s law it follows that the mole of a gas always occupies the same volume when the conditions of temperature and pressure are maintained. The normal molar volume of gaseous substances is 22.4 liters, estimated at a temperature of 0°C and a pressure of 1 atmosphere. This occurs in all ideal gases. A mole contains a specific amount of mass. The ideal gas, also known by the name of perfect gases, responds to a law according to which the particles that make up the gas do not attract or repel each other, and when they collide they are perfectly elastic.
Therefore, the normal molar volume of a gas, whose value is 22.4 liters, only occurs if it is an ideal (or perfect) gas, but not with the so-called common gases; the latter have molecules with volume, although not considerable, which makes their molar volume different from 22.4 liters. In any case, these differences are not very big; for example, while carbon monoxide has this volume, sulfur dioxide and carbon dioxide are 0.5 and 0.1 liters lower, respectively. The notion of partial molar volume Taking into account that the volume of a solution is linked to pressure, composition and temperature, and that it is a large quantity, we can define the concept of partial volume as the rate of change of volume as the quantity increases Of the substance, provided that the values of temperature, pressure and quantity of the other components are kept constant. Partial molar volume is a function of fractional composition, pressure, and temperature; in other words, it is an intensive quantity, and according to its definition, we can say that if the pressure and temperature do not vary, it interferes with the total volume differential. When we change the composition, for example, we add a certain number of substances, since the total volume of the mixture increases, the partial molar volumes of its components also change, and it is done first in the environment of its molecules. The volume occupied by a number of molecules depends on those that are nearby.
