Question

# The (C.H) bond length order in hydrocarbons in which the hybridisation of carbon is $S{{P}^{3}}\text{ or }S{{P}^{2}}\text{ or }SP$(a) $SP-S>S{{P}^{2}}-S>S{{P}^{3}}-S$ (b) $SP-S=S{{P}^{2}}-S=S{{P}^{3}}-S$ (c) $S{{P}^{2}}-S>S{{P}^{2}}-S>SP-S$ (d) $S{{P}^{3}}-S>SP-S>S{{P}^{2}}-S$

Verified
129k+ views
Hint: Hybridisation is the concept of mixing of orbitals leading to formation of a new set of orbitals with the same energy. There are types of hybridisation out of which the more common hybridisation are $s{{p}^{3}},\text{ }s{{p}^{2}}\text{ and }sp$ . The higher the s character of the hybrid orbital lower is the bond length between the orbitals.

- When orbitals mix up and form a new set of orbitals of the same energy is called hybridisation and the new set of orbitals is called hybrid orbitals. There are different types of hybridisation and the common ones are $s{{p}^{3}},\text{ }s{{p}^{2}}\text{ and }sp$.
- $s{{p}^{3}}$ hybridisation involves saturated organic compounds containing only single covalent bonds. $s{{p}^{2}}$ hybridisation is seen in compounds with carbon atoms linked by double bonds and sp is seen in compounds having carbon atoms involved in triple bonds.
- We know that the electronegativity of s character is maximum. The electronegativity of the hybrid orbital is directly proportional to the s character of the hybrid orbital. So, the sp orbital is more electronegative and $s{{p}^{3}}$ hybrid carbon is electropositive in character. $s{{p}^{2}}$ hybrid carbon can be both electropositive and electronegative in character.
The s character of hybrid orbitals is inversely proportional to C-H bond length. So, for sp-s the bond length will be more. Then comes $s{{p}^{2}}-s$ and the shortest bond length is between $s{{p}^{3}}-s$.
Thus, the C-H bond length order in hydrocarbon is $SP-S>S{{P}^{2}}-S>S{{P}^{3}}-S$.