The substances of the real world, as we perceive them with our senses, are characterized by their physical or chemical properties, that is, how they react to the changes that are made on them.
What are Physical properties?
The physical properties are those that can be measured without the composition or identity of the substance is affected. Example of these properties are the density, the melting point, the boiling point, among others.
What are Chemical properties?
There are also chemical properties , which are observed when a substance undergoes a chemical change , that is, a transformation of its internal structure, becoming other new substances. Such chemical changes may be reversible or irreversible , when the latter occur in only one direction (as in the combustion of wood).
The properties of the substances can also be classified as extensive and intensive . The extensive properties are characterized depend on the amount of substance considered (as the mass and volume) A. Intensive properties do not depend on the amount of substance (such as density and temperature).
If a piece of copper is electrified, a piece of iron is immersed, a certain mass of sulfur is heated or a certain volume of chlorine is compressed, the physical properties of these substances vary only with respect to the modification produced and in An extent depending on it, but the chemical properties of these substances remain unchanged; A physical phenomenon has taken place in each case. If the sulfur is melted or the chlorine is liquefied, the physical properties change completely, but the chemical behavior of molten sulfur or liquid chlorine is the same as that of solid sulfur or gaseous chlorine. The process of fusion or liquefaction is also a physical change that affects only the state of aggregation of the corresponding substance. Instead,
CHEMICAL PROPERTIES VS PHYSICAL PROPERTIES . What are the differences?
The physical and chemical processes differ fundamentally in the following aspects:
- Chemical changes are accompanied by a profound modification of the properties of the body or reactant bodies; The physical changes give rise to a very small and often partial alteration of the properties of the body.
- Chemical changes are almost always permanent, whereas, in general, physical changes persist only as long as the cause that causes them changes.
- The chemical changes are accompanied by a significant variation of energy while the physical changes are linked to a relatively small energy variation. Thus, for example, the formation of 1.0 g of water at room temperature, from hydrogen and oxygen, gives off about 3800 calories, while the solidification to ice of 1.0 g of water or the condensation to liquid water at 100 ° C Of 1.0 g of water vapor gives off only, respectively, about 80 or 540 calories.
In some cases, such as in the dissolution of hydrogen chloride gas or even sodium chloride in water or the simple dilution of concentrated sulfuric acid, it seems difficult to decide clearly whether a process is chemical or physical, since it offers aspects of both Type of transformations.
Basically the properties of every substance are classified in two categories, Physical and Chemical properties. Before going towards the differences among them, lets discuss what are physical and chemical properties.