Question

Which of the following statements concerning conformations is/are true?
(1) Ethane has an infinite number of conformations
(2) The eclipsed conformation of a molecule is slightly more stable and energetically favoured than the staggered conformation
(3) A conformation is one specific geometry of a molecule

• A. Only 1 and 3
• B. Only 1 and 2
• C. Only 2 and 3
• D. All 1, 2 and 3

Answer 1

Answer: (A)

Only 1 and 3

(i) Conformation of ethane while there are an infinite number of conformations about any sigma bond, in ethane two particular conformers are note worthy and have special names.

In eclipsed conformation the $C-H$ bonds on the fonts and back carbons are aligned with each other with dihedral angles of 0(zero) degree.

(ii) This is the eclipsed conformation n-butane. This s highly energetic according to energy level diagram Hence, the eclipsed conformation of a molecule does not stable.

(iii) Molecular geometry is the three dimensional arrangement of the atoms that consists a molecule. It includes the general shape of the molecule as well as bond length, bond angles, and any other geometrical parameters that determine the position of each atoms.