Question

Why do alkynes have higher b.p and m.p than alkanes and alkenes?

Answer 1

In alkynes the carbon atoms are bonded by triple bonds which are the strongest. So, more energy is required to break the carbon- carbon triple bond. Alkynes are followed by alkenes. In alkenes, the carbon atoms are bonded to each other by double bonds, so lesser energy than the energy required to break the triple bond is required. But, the least energy is required to break single bonds, thus alkanes have the lowest melting point and boiling point whereas alkynes have the highest boiling and melting point.