7/30/2019 Explain the Difference in Melting and Boiling Points
Caused by the Strength of Chained Alkanoic Acid and Straight
Chained Primary Alkanol Structures
1/2
Explain the difference in melting and boiling points caused by
the strength of chained alkanoic acid
and straight chained primary alkanol structures
Hydrogen bonding is both an intermolecular and intramoecular
bonding type between hydrogen
and either fluorine, Nitrogen, and oxygen.
This is due to the structural difference between alkanols and
alkanoic acids
Nick Keyes addition SHORT-chained esters have low boiling points
compared to alkanols" This is
because esters rely on dispersion forces to bond
inter-molecularly (their active parts are hard to
access when they're in the middle of a massive molecule). Hence,
(because the larger the molecule
the stronger the dispersion forces) smaller esters have
relatively low BPs.
As shown in the diagram left on an intermolecular scale
hydrogen bonds occurs between alkanoic acid functional
groups C O and C=OH groups means that 2 h-bonds
occur between individual molecules of alkanoic acids
This affects the physical properties of alkanoic acids
giving
then a higher melting and boiling point. As well as this
increases this boiling and melting points verses alkanols
because there is more energy needed to break the
hydrogen bonds between molecules 2 vs. 1.
As shown in the diagram left intermolecular bonds
occur between alkanols which increases there boiling
and melting points as more energy is needed to
overcome the intermolecular bonds, the major
difference is that alkanols only bond once with
other alkanol molecules and therefore there boiling
and melting point is less than that of alkanoic acids as
will be shown.
