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Formula Ideal gas Internal energy    Degrees of freedom    Temperature    Stoffmenge   

Formula: Ideal gas

Internal energy

Internal energy is the total energy of molecules or atoms of an ideal gas that is in thermodynamic equilibrium.

Degrees of freedom

Number of degrees of freedom of a particle of the gas. In the three-dimensional case and without particles being able to rotate and vibrate, \( f = 3 \). The more degrees of freedom the gas has, the greater the internal energy of the system.


Absolute temperature of the system, that is the temperature of a gas. The greater the temperature, the greater the internal energy.


The amount of substance \(n\) is the ratio between the number of particles \(N\) and the Avogardo constant \(N_{\text A} = 6 \cdot 10^{23}\):$$ n = \frac{N}{N_{\text A}} $$

So in one mole of gas there are \(6 \cdot 10^{23}\) gas particles.

Gas constant

Gas constant is a physical constant appearing in thermodynamics. It has the following value: $$ R ~=~ 8.314 \, \frac{ \mathrm{J} }{ \mathrm{K} \, \mathrm{mol} } $$