The alterations that affects various forms of chemical substances by not affecting the chemical composition is known as Physical changes. The incorporation of physical changes can lead to the separation process of mixtures to component compounds. However, physical changes cannot be implemented for the process of separating simpler compounds from the compound elements. The concept of physical changes is contrasting with the chemical changes, where the new substances are formed by the breakage of one or more substance. The application of physical means can directly influence the reverse process of physical changes. The reversal process can be understood by the example of extracting salt from its dissolved state in water. The process of evaporation can lead to the reversal of the physical changes. The alterations in the physical properties of compound is known as physical change. The changes in physical properties includes, transition to gas, melting process, changes in the feature of durability, textural changes, changes in density, color and volume, and the process of crystallization. Another example of physical change can be the procedure of moderating the component of steel for the construction of blade or knife. The shape and form of steel changes in the influence of physical processes like, hammering and heating for changing the physical properties of steel, sharpness, hardness and agility. Conversion of water into crystals by shifting the composition of atoms and rearranging for executing the crystallization process also depicts the physical changes. One of the basic classification of physical changes and chemical changes is the phenomenon of irreversibility. In majority of the cases, the changes in physical properties can be reversed by incorporating physical stimulus whereas the changes in the chemical composition of compound cannot usually undergo the reversal process.

During the process of combining substances with each other for constructing a new compound or breaking the molecular and chemical composition of compound for deducing new compound, chemical changes can be witnessed. The process of combining two or more substance together for the purpose of forming new compound is termed as chemical decomposition or chemical synthesis. Usually, chemical changes cannot be reversed except in the case of incorporating further chemical reactions. The chemical reactions that are responsible for causing heat energy is known as exothermic reactions. The reactions that marks the need for heat energy in initiating the process is known as endothermic reaction.  The understanding regarding chemical changes can be considered a major section of Chemistry. The new products or compounds are constructed for the purpose of stimulating chemical changes through the process of rearranging and restructuring the state of atoms with the association of energy changes. For instance, the reaction of water and sodium in generating hydrogen and sodium hydroxide can reflects the process of stimulating chemical changes. This process of new compound construction leads to a high energy extraction. This is a suitable instance for depicting a chemical change as the new substance or compound depicts different chemical composition. Some of the examples of physical changes are the process of dissolving sugar or salt in the water. The melting of the structure of ice in water is another instance of physical changes. In the same of freezing water molecules is another example of physical changes. Boiling water and melting wax component indicates the physical changes of components. The examples of chemical changes are burning paper, burning wood and burning camphor. Another example depicting chemical changes is the souring process of milk. Burning candles, a typical chemical reaction, rotting of eggs and digestion of food can be another set of instances depicting chemical changes. Rusting or development of brownish component over the surface of iron, iron oxide also indicates the state of chemical changes.

The features of physical changes are usually noticeable as the changes does not lead to a completely new compound or component. The feature of physical changes can lead to the changes in texture. Another feature of physical change can be the change in colors in the final component. Another feature of physical change can be the alteration in the shape of component but not changing the chemical composition of the actual component. Changes in the temperature of the actual component can be another feature of incorporating physical changes. The feature of physical changes can incorporate changes in the state of actual compounds. Alterations in the molecular composition of the compound leads to the changes in state of compounds. Physical changes does not involve energy changes in the process of incorporating changes. The nature of the physical changes are usually temporary and reversible.

The features of chemical changes cannot be reversed until the addition of further chemical reaction. Temperature changes in the process of chemical changes. Chemical changes leads to the release or/and use of chemical energy in the form of temperature. For instance, heat energy released in thermite reaction, cause of fireworks. Another feature can be the change in color from a process of executing chemical reactions. For instance, the iron components can develop rust in its surface causing the formation of reddish brown component. The color changes in chemical change is caused by oxidation reaction or phenomenon. Changes in odor is another feature or characteristics of chemical changes, the presence of noticeable odor changes during a chemical reaction reflects the state of chemical changes. For example, the odor changes in case of rotten eggs, which is stimulated with the process of irreversible decomposition. Another feature of chemical changes is the creation of precipitate. The formation of a solid compound as a result of a chemical change is termed as Precipitate. The foam caused during the usage of soap or detergent under hard water reflects the chemical changes on the detergent. In chemical changes, the molecular compound gets completely altered. The nature of chemical changes are usually permanent and irreversible. The irreversible feature or nature can be altered with the incorporation of further chemical reactions. Mass of the components are altered in case of the chemical changes. Changes in energy usage or release occurs in the incorporation of chemical changes.