The Actual Difference Between Physical and Chemical Properties

Example of physical and chemical properties
It is necessary to know the difference between physical and chemical properties in order to study the nature of a specific substance. This piece provides some information about these properties and a comparison between the two.
Physical properties of a substance are those which can be observed without changing its composition. The chemical properties are those which become evident during a chemical reaction involving that substance.
All substances are known to have properties by which they can be identified. These properties can be classified into two basic types; namely, physical and chemical.
Physical Properties
◼ These are the properties that are observable and that describe a substance without changing its identity. That is, the composition of matter does not change. Common examples of physical properties of a substance include color, texture, odor, melting point, boiling point, density, solubility, polarity, etc.
Melting ice
◼ In this case, the substance may undergo a physical change but not a chemical change. By physical change, we mean the changes in the state or phase of matter. Matter is known to exist in four phases, which are solid, liquid, gas, and plasma. When a substance undergoes this kind of a change (such as melting, freezing, condensation, etc.), it does not become a new substance. An example is the melting of ice.
◼ Let's take the example of calcium. It is a silvery-white metallic solid and its crystalline structure is cubic. What we just described were some of calcium's physical properties (those which are observable without changing its identity).
◼ Physical properties can further be classified into two types, based on the changes in the amount of matter. They are intensive and extensive.

◼ Intensive properties are those in which the physical property is not altered by the size or mass of the sample. Some examples of this type are color, luster, density, malleability, etc.

◼ Extensive properties are those in which the physical property is altered with a change in the amount of matter in the sample. Some examples of this type are mass, volume, and length.

◼ One may have come across terms like isotropic and anisotropic properties. They are related to physical properties. Physical properties become isotropic or anisotropic based on their dependency upon the orientation of a sample. That is, they are considered as anisotropic properties if they depend on the direction from which the sample is observed and they are isotropic if this does not apply.
Chemical Properties
◼ These are the properties which are observable or measurable only after the substance undergoes a chemical change. Here the chemical identity of the substance is changed. Common examples of chemical properties include toxicity, chemical stability, heat of combustion, enthalpy of formation, flammability, reactivity with other chemicals, etc.
Rusted rod
◼ Here, the substance undergoes a chemical change. By chemical change, we mean changes in the molecular structure or a change that involves the making and breaking of atoms, thus, forming a new chemical substance. Examples include rusting of iron or milk going sour.
◼ Let's continue with the example of calcium. It is used as a deoxidizer in steel (property: oxidation). It ignites when heated in air or oxygen (property: flammability). And it reacts with acids (property: reactivity). Here, we could describe the properties with the help of chemical activities involving calcium. These were some of calcium's chemical properties (those which are evident only after a substance undergoes a chemical change).
Definition
Physical Property
◼ It can be defined as an observable property that can describe a substance without changing its identity.

Here, the chemical identity of the substance does not change.

A physical change may involve a change in the arrangement of matter in a sample, however, not in the structure of its molecules.
Chemical Property
◼ It can be defined as the property of a substance that can be observed or measured when the substance undergoes a chemical change.

Here, the chemical identity of the substance is changed, resulting in the formation of a new substance.

A chemical change involves a change in the molecular structure.
Examples
Physical Property
◼ Color, texture, density, odor, polarity, infra-red spectrum, opacity, viscosity, solubility, electrical conductivity, thermal conductivity, ductility, malleability, etc.
Chemical Property
◼ Enthalpy of formation, flammability, chemical stability, electromotive force, heat of combustion, toxicity, reactivity with other chemicals, coordination number, etc.
Both the physical and chemical properties are important as they enable us to know or study the nature of a particular substance. Furthermore, the substance can be modeled and its behavior under various conditions can be understood, studied, and used in further applications.