In the `HCI` molecule, the separation between the nuclei of the two atoms is about `1.27Å (1Å = 10^(-10)m)`. Find the approximate location of the c.m of the molecule, given that a chlorine atom is about `35.5` times as massive as a hydrogen atom and nearly all the mass of an atom is concentrated in its nucleus ?

Explanation

Let mass of Hydrogen=m
Mass of Chlorine = 35.5 m

Let distance of centre of mass from Hatom = x So distance of centre of mass from Clatom
`=(1.27-x)Å`
If c.m. is taken at origin then
`mx=(35.5)m(1.27-x)
`x=+35.5xx1.27-35.5x`
`x+35.5x=+35.5xx1.27`
`36.5x=45.085`
`x=1.235Å`
Thus c.m. is located at a distance of 1.235 A from hydrogen atom.