Showing posts with label mole. Show all posts
Showing posts with label mole. Show all posts


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 Drift velocity of charge carriers per unit electric field


If the same value appears a number of times in the data, this value is called mode.


It is referred as method of slowing down of neutrons in the range from fission energies to roughly below 1eV.


Substance used to reduce the energy of neutrons, called thermalization. Good moderator is a substance having low absorption crossection, low atomic weight and high scattering crossection.


 Substance which can slow down neutrons with minimum absorption. Generally moderators do shall have i) Large scattering crossection ii) Small absorption coefficient iii) Low atomic number


Process of sending electrical audio signal by superimposing it on high frequency carrier wave for easy transmission to longer distances.


The transmission of electrical energy radiatively is practicable only at high frequencies e.g., above 20KHz . In order to transmit audio signal properly, process of superimposing electrical audio signal on high frequency carrier wave. The resultant waves are known as modulation waves and process is called modulation.

Modulus of Elasticity

The ratio of stress to strain when deformation is totally elastic; it is measure of stiffness of a material.

Modulus of Resilience

The strain energy per unit volume required stress a material from an unloaded state up to the point of yield.   

Modulus of Rigidity

The ratio of tangential stress to shearing strain within the elastic limit is called rigidity modulus.

Molar Gas Constant

The molar gas constant, also known as the universal molar gas constant, is a physical constant that appears in an equation defining the behavior of a gas under theoretically ideal conditions. The gas constant is, by convention, symbolized R. The gas constant has been found, by experiment, to have a value of approximately 8.3145 Joules per Kelvin per Mole (J · K-1 · mol-1).

Molar Specific Heat

Amount of heat required to raise the temperature by one degree centigrade or one Kelvin.


Chemical quantity used to describe concentration of solute in solution. It is defined as no. of moles of solute per liter of solution.


Shaping a plastic material by forcing it , under pressure and at an elevated temperature  is called as a molding.


It is the quantity of a substance, which corresponds to Avogadro’s number i.e. 6.023 x 1023 atoms.   


Quantity of any substance whose mass, in grams is numerically equal to its molecular weight is called a mole.

Molecular Range

The maximum distance up to which a molecule exerts force of attraction is called as molecular range.

Molecular Spectrum

Spectrum which arises from rotation of a molecule as a whole and vibrations of its constituent atoms relative to one another as well as changes in its electronic configuration.

Molecular Weight

It is the sum of atomic weights of all atoms in a molecule.   


A molecule is the smallest particle in a chemical element or compound that has chemical properties of that element or compound. Molecules are made up of atoms that are held together by chemical bonds.

Moment of Inertia

 It is the inertia of rotation of a body about the given axis.


Physical quantity which represents product of mass and velocity is called momentum.

Monochromatic Aberration

Aberrations formed in images formed by spherical mirrors and lenses when the source of light is monochromatic.

Monochromatic light

Technically light having single wave length is referred to as monochromatic wavelength. But no electromagnetic wave is purely monochromatic. Hence monochromatic light is said to have a wavelength within a short wavelength range.   

What is Chemical Potential?

For a chemical system, molar free energy is known as Chemical Potential.

A chemical substance that is free to move from one place to another place, will move spontaneously from a state of higher chemical potential to a state of lower chemical potential.

In the position of equilibrium, the chemical potential is constant through the entire system.

Let us consider a general heterogeneous system consisting of an independent components in several coexisting phases.

To start with, it is convenient to describe a given phase by its chemical composition, which is specified by the no. of mole 'Ni' of each species i, its volume V and its entropy 'S'.

If we consider internal energy (U)

μi=❴∂U/∂Nᵢ❵S,V,Nj ; j= except 'i'

'μi' is chemical potential of component 'i' in given phase.

dU=TdS-PdV+Σμᵢi.dNᵢ for i=1...n

We can also consider chemical potential 'μ' in terms of Helmoltz free energy 'F'.

F = F(T,V,N₁,N₂......Nn)



The chemical potentials are thus the rate of change of free energy per mole, at constant volume and temperature.

μ can also be expressed as


A System in external field will be in equilibrium if the temperature and chemical potential of each component of the system is constant through out, i.e.

dT₁=0 and dμᵢ=0

Perfect Gas Law

In the kinetic theory of gases, an ideal gas is one in which the individual molecules are sufficiently far apart that the short range force that acts between them can be ignored. Collisions between molecules are assumed to be perfectly elastic.

Laboratory experiments have shown that for such a gas there is a simple equation of
state relating the pressure p, absolute temperature T, and volume V. For m kilograms of
gas, this equation may be written
pV = mRT,
where R is a constant for the particular gas. R is called the gas constant and has units of
Joules per degree per kilogram.

We define a kilogram-molecular weight, or kilomole (abbreviated kmole) of a material
as its molecular weight expressed in kilograms. (Older texts define molecular weight as
the molecular weight expressed in grams).

For example, the molecular weight of water is 18.016, and therefore one kilomole of water is 18.016 kg of water. The number of kilomoles n in mass m (in kilograms) of material is given by

n = m/M.

Where M is the molecular weight. One kilomole of any material is equal to the weight of a single molecule (in kg) times the number of molecules, N. This number is called Avogadro's number and has the value 6.022 ×1026 (for a kmol of substance).

Avogadro hypothesized that gases containing the same number of molecules occupy the same volume at the same pressure and temperature. This implies that for one kilo mole of any gas
pV = MRT

Accordingly, R* = MR is a universal constant for all gases. It is called the universal gas constant and has the value 8314.3 J deg −1 kmol −1 .