In general, high potential energy systems are unstable and likely to change if they have...

In general, high potential energy systems are unstable and likely to change if they have a way to change. Because single bonds can rotate freely, ethane in the eclipsed (highest P.E.) conformation is not stable (see Newman Projection in CTQ 2).

a. (E) What conformation of ethane is “downhill” in terms of potential energy from the eclipsed conformation?

b. What repulsive force(s) will cause ethane in the eclipsed conformation to quickly adopt the conformation you cited above?

(Reference CTQ 2)

The conformation at right is called eclipsed. It is the least favorable (highest P.E.) conformation of butane.

a. (E) Explain the names staggered and eclipsed.

b. Construct an explanation for why the staggered conformation is more favorable than the eclipsed conformation. (Both are “conformers” or “conformational stereoisomers” of ethane.)