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Basic formulas of molecular physics

Molecular physics is an extensive branch of physics,which studies the structure of matter at the molecular level, changes in the macroparameters of the system under the influence of the external environment, phase transitions. The properties of polymers and plasma are also explored by molecular physics. The formulas and definitions of this section, which are useful in solving problems, are given in this article.

The basic concepts of the section

A molecule is the smallest unit of a substance with all its properties.

An ideal gas is a gas for which powerintermolecular interaction is zero, the molecules are considered as material points, and the blows between them are absolutely elastic. Many formulas of molecular physics are applied with respect to the ideal gas.

Molecular Physics Formulas

Energy is a quantity that characterizes the ability of a system to perform work.

Work - the amount of energy transferred to the system through a change in its parameters.

Other concepts in this section:temperature, internal energy, potential energy, diffusion, thermal conductivity, amount of substance, heat capacity, evaporation, condensation, crystallization, saturated steam.

Basic formulas

Molecular physics formulas linkbetween different system parameters. The main formulas in this section include the Clapeyron equation, which describes the state of an ideal gas, the laws of Boyle, Charles and Gay-Lussac.

The Clapeyron equation is written as:

pV = nRT

Here p is the pressure, n is the amount of substance in moles, R is the universal gas constant, T is the temperature in Kelvin, V is the volume occupied by the gas.

From this formula of molecular physics, using simple transformations, other laws of state are obtained:

pV = const (formulation of the Boyle-Mariotte law, which applies to the isothermal process);

V / T = const (the first Gay-Lussac law, which applies to the isobaric process);

p / T = const (the law of Charles, applies to the isochoric process).

Molecular physics formulas and definitions

Other important formulas of molecular physics:

n = m / M = N / Na (formula for finding the amount of a substance).

p = nkT.

In the last formula, n is the concentration, k is a constant, the Boltzmann constant.

E = (3NkT) / 2 (formula for finding thermal energy).

p = p1+ n2+ ... + nand (formula for determining the pressure of a mixture of gases, known as Dalton's law).

Formulas of thermodynamics and statistical physics

Statistical physics is also a section of molecular physics. Some formulas of molecular physics used in statistical physics and thermodynamics are given above.

Q = mc (t2-t1)

Q = A + (U2-U1) (Yand - internal energy)

dH = TdS + Vdp

Here H is the enthalpy.

G is the Gibbs energy, or thermodynamic potential.

V = dG / dp

S = -dG / dT (S is the entropy, the value introduced by Clausius, a measure of probability).