Given the following Newman projection of ethane viewed down the $C_1-C_2$ bond, which bond-line structure does it represent? (Front carbon: three hydrogens; back carbon: three hydrogens; all staggered)

For each pair of conformations shown, choose which is most stable. [If both conformations have the same number of gauche interactions, choose the one where the interactions are between smaller groups.]

(f)

Which of the following structures represent the same compound? Which ones represent different compounds?

(f)

Construct a graph, similar to Figure 3-11, of the torsional energy of 3-methylpentane along the C2―C3 bond.

a. Place C2 in front, represented by three bonds coming together in a Y shape, and C3 in back, represented by a circle with three bonds pointing out from it.

b. Define the dihedral angle as the angle between the methyl group on the front carbon and the ethyl group on the back carbon.

Calculate the dihedral angle (θ) for the conformations shown.

(c)

Which of the following diagrams correctly represents a Newman projection for propane when viewed along the $C_1–C_2$ bond?

Which of the following diagrams represents a Newman projection of butane?

Given the following Newman projection of ethane looking down the $C–C$ bond, which of the following wedge and dash structures correctly represents the same conformation?

Which of the following correctly represents the staggered conformation of ethane in a Newman projection when viewed down the $C–C$ bond?