Physical Property

A physical property is the characteristic of a matter which can be measured without altering its composition. It is used to describe the matter under the study. Since a physical property involves changes in the physical characteristics of a substance, such as shape, size, colour and others, most of them are reversible. For example, when water freezes, it turns into ice, but when it melts, it returns to its original state, i.e., water. Some physical properties, however, are irreversible when the original form of the substance can be restored. Mass, colour, density, volume, melting point, boiling point, shape, electrical conductivity, etc., are all physical properties of a matter. 

Intensive and Extensive Properties:

Physical properties are classified as intensive and extensive properties. An intensive property is a bulk property that does not depend on the size or the quantity of the matter, whereas an extensive property depends on the size and quantity of the matter. Properties related to the appearance of the substance are, therefore, its intensive properties. For instance, the colour of any substance remains unaffected by the quantity and hence is regarded as its intensive physical property. Intensive properties remain constant and are therefore helpful in identifying a substance regardless of its quantity. For example, sulphur, a yellow crystalline solid, has a melting point of 115.2 °C and does not conduct electricity, no matter how much of it is used.

Since extensive properties depend on the amount and size of the matter, they change as the amount changes and are usually used to determine the concentration of a substance in a sample. For example, mass is an extensive property that is determined by how much matter there is in the sample. Similarly, volume and length change as the quantity of matter changes, which are other examples of extensive properties.

Although mass and volume are both extensive properties of a matter, the ratio between them, called density, is an intensive property. Density is measured in grams per cubic centimetre (g/cm3) and is defined as mass per unit volume.

Types of Physical Properties:

Matter (a substance with mass and volume that occupies space) possesses both physical and chemical properties. The physical qualities of a substance aid in its observation and identification. The section that follows goes through some of these physical properties of matter in greater depth. 

Mass:

A physical property that represents the amount of matter present is called the mass of the matter. It is expressed in kilograms or grams. 

Volume:

The amount of space occupied by a solid, liquid or gaseous substance is called its volume. It is usually expressed in cubic metres. 

Colour:

The hue of an object as perceived by humans is defined as the colour of a material.

Melting point:

When a pure solid substance is heated to a certain temperature, it finally transforms into a liquid state; this temperature is known as the melting point of that substance. It is expressed in degrees Celsius, Fahrenheit or Kelvin.

Boiling point:

The temperature at which a pure liquid transforms into a gas is known as the boiling point of that liquid. It is expressed in degrees Celsius, Fahrenheit or Kelvin.

Freezing point:

The temperature at which a pure liquid changes back to a solid-state is known as the freezing point of the liquid. However, certain substances such as glass do not change into a solid state upon freezing and are, hence, called as super-cooled liquids. It is expressed in degrees Celsius, Fahrenheit or Kelvin.

Electric conductance:

It is defined as the ability of a substance to conduct electric current. The SI unit of electric conductivity is Ω–1 m–1 or Siemen per metre.

Solubility:

It is defined as the ability of a substance to dissolve into a solvent. The solubility of most of the substances usually increases with an increase in temperature. 

Viscosity:

Viscosity is the resistance of a fluid (liquid or gas) to progressive deformation by shear or tensile stress. It is proportional to the fluid’s thickness.

Thermal conductivity:

The property of a substance to conduct heat, i.e., the ability to transfer heat through a material by conduction. 

Density:

The density of matter is a measure of how tightly packed the particles are. It is the ratio between mass and volume of a substance calculated using the formula:

Density (D)=Mass (M)/Volume (V)

It is expressed in grams per cubic centimetre (g/cm3).

Difference Between Physical and Chemical Properties:

Physical properties differ completely from the chemical properties of matter. Therefore, learning the difference between physical and chemical qualities is very helpful in understanding physical properties.

Conclusion

This chapter contains physical property notes and includes sections such as

• Introduction to physical property
• Properties of matter
• Types of physical properties
• Difference between the physical and chemical properties of a matter

We hope you will find these easy-to-understand physical property notes useful in preparing for the IIT-JEE (Advanced) entrance exam. Best wishes for a successful start to your exam preparation.