Density vs Concentration
Density and concentration are two basic and important topics discussed under chemistry and material sciences. These concepts are encountered on a daily basis, and it is necessary to have a thorough understanding on such concepts. This article will discuss the basic definitions of density and concentration, their similarities and finally the differences.
Density
Density is an important characteristic of matter. It is directly connected with mass. Therefore to get a clear understanding about it is vital to have a clear understanding about mass. Mass is defined as a measurement of inertia of an object. Density, in the most primitive form, is defined as the mass per unit volume. For a bulk material with uniform mass distribution, density can be easily calculated by dividing the total mass of the object by the total volume occupied. If the mass distribution is not even, more complicated methods are required to measure the density. Floatation is an important phenomenon that can be described using density. A fluid or a uniform solid denser than a given fluid will drown in the given fluid. If the density of the fluid or the uniform solid is lesser than that of the given fluid, it will float on the given fluid. A term called relative density is defined in order to compare the densities of two fluids. This is the ratio of the two densities and is merely a number.
Concentration
Concentration is another important concept in chemistry. In a qualitative sense, concentration is the amount of one compound in a solution. There are several types of concentrations defined. The mass concentration is the mass of the given compound in a unit volume. The units are mostly g / dm^{3}, but other units are also used. The molar concentration is the number of moles of the given compound in a unit volume. The units of this definition are mol / dm^{3}. The number concentration is the number of molecules of the given compound in a unit volume. The unit of this is dm^{3} (per cubic decimeter). The volume concentration is the volume fraction of the considered compound from the total volume of all compounds before mixing. All of these concentrations are interconnected. The molar concentration can be obtained by dividing the mass concentration by the relative molecular weight of the given compound. The number concentration can be obtained by multiplying the molar concentration by the Avogadro number. And the derivation of the pressure concentration requires the ideal gas equation. Concentration is also expressed in ppm, which means parts per million. It is a very useful form when expressing small concentrations. The concentration of a nondissolvable solid is a constant and does not depend on the volume.
What is the difference between concentration and density? • Density is a property depending only on the amount of matter within a given volume. Concentration depends on the amount of matter and what compound is in there, as well. • Generally, concentration is defined to solutions, and it is a main property of solutions. Density is defined to all three states of matter. • Concentration is always a homogeneous property while density may vary depending on the material.

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