Calculate the approximate ratio of the binding energy of O₂(about 5eV) to the rest energy of O₂. Most oxygen nuclei contain 8 protons and 8 neutrons, and the rest energy of a portion or neutron is about 940 MeV. Do you think you could use a laboratory scale to detect the difference in mass between a mole of molecular oxygen (O₂)and two moles of atomic oxygen?

The binding energy of O₂ is E_B = 5eV,

The rest energy of the proton or neutron is mc²= 940 MeV

Also, m_pc²= m_nc²

The energy that is stored inside a stationary particle as a result of its mass. The binding energy, amount of energy required to separate a particle from a system of particles or to disperse all the particles of the system.

Now, calculate maximum rest energy of an oxygen molecule:

$\begin{array}{rcl}{E}_{rest,o_2}& =& 2m_{\circ }{c}^2\\ & =& 2(8m_p+8m_n)c^2\\ & =& (16m_p+16m_n)c^2\\ & =& 32\times 940MeV\left(\frac{{10}^{6}eV}{1MeV}\right)\\ & =& 3.008\times {10}^{10}eV\end{array}$

The ratio of Binding energy and the Rest energy of the molecule is then:

$\begin{array}{rcl}\frac{E_B}{E_{rest,o_2}}& =& \frac{5}{3.008\times {10}^{10}}\\ & =& 1.66\times {10}^{-10}\end{array}$

Because today's experiment does not have this solution, it is not possible to distinguish 1 mole of an oxygen molecule from 2 moles of an individual.

Hence, the ratio of the binding energy and the rest energy of the molecule is $1.66\times {10}^{10}$. It is not possible to distinguish one mole of an oxygen molecule from two moles of individual atoms.