Question

Kinetic energy of oxygen molecule at $0C$ is $5.64\times {10}^{-21}J$. Calculate Avogadro's number.

Answer 1

Given,

$K=5.64\times {10}^{-21}J$

$T=273K$

Kinetic energy, $K=\frac{3}{2}{k}_{B}T$

$k_B=\frac{2K}{3T}$

$k_B=\frac{2\times 5.64\times {10}^{-21}}{3\times 273}=1.3\times {10}^{-23}$

Avogadro number, $N=\frac{R}{k_B}$

$N=\frac{8.314}{1.3\times {10}^{-23}}=6.3\times {10}^{23}$