# Two Important Equations in the JEE Chemistry Syllabus 759 Views

## Van der Waals Equation

Van der Waals equation is often considered to be a modified expression of the ideal gas equation. It suggests that all gases feature perfectly elastic collisions between the point masses that they consist of. Thus, the physical state of a real gas can be defined with the help of the Van der Waals equation. This equation provides the following relationship between the pressure exerted by a gas, the volume occupied by the gas, the absolute temperature of the gas, and the number of moles of the gas:

[P + (an2/V2)]*[V – nb) = nRT

Where,

• P is the pressure associated with the gas.
• ‘a’ and ‘b’ are constants that are specific to each gaseous substance.
• V is the volume occupied by the gas.
• n is the number of moles of the gas.
• R is the universal gas constant.
• T is the absolute temperature of the gas (in Kelvin).

It is important to note that the constant ‘a’ is expressed in the units atm.litre2.mol-2 and the constant ‘b’ is expressed in the units litre.mol-1.

## The de Broglie Equation

As per the de Broglie equation, all matter can exhibit wave-like behaviour in a manner that is similar to the way light and other forms of electromagnetic radiation can exhibit particle-like behaviour. It goes on to explain how a beam of electrons can undergo diffraction in a manner that is similar to the way a beam of light undergoes diffraction.

The de Broglie equation suggests that every moving particle has a wavelength associated with it. However, the wave nature of matter is only detectable at the microscopic scale (tiny particles with extremely low masses). The de Broglie equation can be written as follows:

λ = h/mv

Where,

• λ is the de Broglie wavelength of the particle.
• h is Planck’s constant.
• m is the mass of the object.
• v is the velocity of the object. 