Absolute Zero

Key Questions

It is the point at which particle motion stops for monatomic ideal gases. However, molecules will still vibrate.

Explanation:

All temperatures above absolute zero will cause particles in any material to move/vibrate slightly, as temperature gives particles Kinetic energy, according to the equipartition theorem for monatomic ideal gases:

${K}_{a v g} = \frac{3}{2} {k}_{B} T$

${k}_{B}$ = Boltzmann's constant = $1.38065 \times {10}^{-} 23 J / K$
$T$ = absolute temperature (Kelvin)

At absolute zero, $T = \text{0 K}$, so there is effectively no average kinetic energy of the molecules. (although the state of absolute zero is more of a concept as it has not yet been achieved). This means that particle motion ceases in monatomic gases.

Absolute zero is also the foundation for the Kelvin scale, as $\text{0 K" = -273.15^@ "C}$ is the coldest that you can ever hope to get.

• Absolute zero is the temperature at which enthalpy and entropy of ideal gas reaches zero.

In Kelvin scale this temperature is taken as $0$ Kelvin.