Thermodynamic system: a macroscopic object composed of a large number of microscopic particles that can be perceived by us

Outside: outside the system and related to the system

Equilibrium state: A system that is not affected by external conditions reaches a stable state in which its macroscopic properties no longer change with time after a long enough period of time. (Dynamic balance, ideal state)

Temperature: t-=T=273k

Pressure: 1atm=1.013*10⁵Pa

Equation of state: pv=mRT (m is the molar quantity, R is the gas universal constant R=8.31(J/(mol*k))

Process equation: p1v1/T1=p2v2/T2

p=nkT(n=N/V molecular number density)(k is Ertzmann’s constant k=R/Na=1.38*10^⁻²³)

Matter is composed of a large number of molecules, atoms and other microscopic particles

The molecules of matter are in a state of constant and irregular motion

There are interactions between molecules (attraction and repulsion)

Microscopic model of an ideal gas

ideal gas pressure formula

Temperature formula: Ek=3/2*kT

Ek has nothing to do with the properties of the gas. At the same temperature, the average translational kinetic energy of all gas molecules is the same.

Root mean square rate: √v²=√3kT/m=√3RT/M

Degrees of freedom: The number of independent coordinates required to determine the position of an object

Molecular energy by degrees of freedom

internal energy of ideal gas

Maxwell's gas molecule velocity distribution law: f(v) represents the probability of molecules in a certain velocity range, and only applies to equilibrium states

Low temperature (high mass), narrow curve, small most probable velocity, large peak value

Most probable rate: The highest number of molecules appears near this point with the greatest probability, that is, the highest point in the curvature. vp=√2kT/m=√2RT/M

Average rate: the average rate of all molecules, v=√8kT/pm=√8RT/pM

root mean square rate

Average degree of freedom: the average distance traveled by a molecule between two consecutive collisions, l

Average collision frequency: the average number of collisions between each molecule and other molecules per unit time, z

The relationship between the two: l=v/z (v is the average speed)

z=√2pd²vn

l=1/(√2pd²n)=kT(√2pd²p)