Chemical Forums
Chemistry Forums for Students => High School Chemistry Forum => Topic started by: Jim42 on October 18, 2007, 05:17:44 PM
-
why is the melting point of 1-butanol higher than that of 1-propanol?
I realize that the longer your carbon chain the more intermolecular forces will be present and therefor you will have higher melting points. But my question is how can I explain this trend in melting points of these 5 primary alcohols
methanol -93.9
ethanol -117.3
1-propanol -126.5
1-butanol -89.53
1-pentanol -79
all temperatures are in degrees celcius i have looked at what could happen with the hydrogen bonding and could not find anything. I'm wondering why from methanol to 1-propanol they require less and less energy to break the bonds and then 1-butanol and 1-pentanol require more energy. The pattern does not make sense to me.
-
longer hydrocarbon chain means higher van der Waals forces, aka higher melting point
-
Thanks for the comment on Van der Wal forces. By that logic though it would seem to me that menthanol and ethanol with shorter chains should have lower melting point?