Draw a potential energy diagram for the conformational analysis of n-butane as it rotates around the single bond between C2 and C3.

Hint: One C—H bond eclipsed with another C—H bond contributes to 4.2 KJ/mol, one C—H bond eclipsed with a C—CH₃ bond contributes 5.4 KJ/mol while One C—CH₃ bond eclipsed with a C—CH₃ bond contributes 13 KJ/mol to torsional energy. Similarly, Gauche (60° methyl group) will add 3.8 KJ/mol energy.