Question

. Which of the following would have the shortest C-C bond length CH3CH3 CHCH - CH2CH2 All have the same bond length CH3CH2OH

Answer 1

The molecule having shortest C-C bond is acetylene (CHCH)

Step-by-step explanation:

Note : CH3CH2OH has longest bond length

The bond length order from longer to shorter is :

CH3CH2OH > CH3CH3 > CH2CH2 > CHCH

(More bond order shorter the bond length)

The C-C bond length in Ethanol
`CH_(3)CH_(2)OH` is more than ethane

• Here there is single bond between the carbons

• 
  `sp^(3)-sp^(3)` overlap

• It has lowest Bond-dissociation energy (88 Kcal/mole)

The C-C bond length in Ethane
`CH_(3)CH_(3)` is 1.54 Angstrom

• Here there is single bond between the carbons

• 
  `sp^(3)-sp^(3)` overlap

• It has low Bond-dissociation energy (90 kcal/mole : means bonds are long and broken easily but 2 kcal/mole stronger than ethane)
• Bonds are shorter than ethanol.

The C-C bond length in Ethene
`CH_(2)CH_(2)` is 1.34 Angstrom

• Here there is double-bond between the carbons

• The C-C bond distance is shorter than ethane
• 
  `sp^(2)-sp^(2)` overlap

• It has high Bond-dissociation energy than ethane (bonds are stronger than ethane)

The C-C bond length in acetylene

`CH_(2)CH_(2)` is 1.20 Angstrom

• Here there is triple-bond between the carbons
• 
  `sp-sp` overlap

• The C-C bond distance is shortest of all

• It has maximum Bond-dissociation energy.Strongest and shortest bond