Is Octane polar or nonpolar? – Polarity of C8H18
The question is –
Is Octane (C8H18) polar or nonpolar?
⇒ Octane (C8H18) is non-polar.
Octane (C8H18) is non-polar as it consists of symmetrically arranged non-polar C-C and weakly polar C-H bonds.
The small dipole moments of weakly polar C-H bonds get canceled equally in opposite directions to yield an overall non-polar molecule (net µ = 0).
The C8H18 molecule consists of seven C-C and eighteen C-H single covalent bonds.
Each C-C bond is purely non-polar as it consists of identical carbon atoms having a zero electronegativity difference.
In contrast, a C-H bond is only weakly polar (almost non-polar as per Pauling’s electronegativity scale) as an electronegativity difference of 0.35 units exists between a carbon (E.N = 2.55) and a hydrogen (E.N = 2.20) atom.
However, it is due to the symmetrical tetrahedral shape of C8H18 w.r.t each C-atom that the small C-H dipole moments get canceled equally to yield an overall non-polar molecule with a net zero resultant dipole moment.
Also, check –
⇒ How to identify polar or nonpolar compounds?
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