IMF's and Boiling Points Flashcards
What affects the IMF of a molecule?
The type of molecule and its functional group.
What type of IMF do Alkanes, Alkenes and Symmetrical Halo-alkanes have?
London-type IMF
What type of IMF do Haloalkanes and Esters have?
Dipole-Dipole IMF
What type of IMF do alcohols and Carboxylic Acids have?
Hydrogen bond type IMF
What is the order of strongest IMF to weakest?
Carboxylic Acid > Alcohol > Esters/Halo-alkanes > Alkanes/Alkenes
The ___ the interaction between the molecules, the more energy required to overcome the interaction, and the ___ the boiling point of the molecule.
Stronger Higher
Why do alcohols experience hydrogen bonding?
The lone pairs on the oxygen atom can form a hydrogen bond with the hydrogen atom of another molecule.
What type of forces do the carbon chain of alcohols experience?
London-type of IMF.
What type of force does the O-H bond of a carboxylic acid?
Can form hydrogen bonds with O-H of other molecules.
What type of force does the C=O bond of a carboxylic acid?
The C=O can interact to form dipole-dipole interaction with other molecules.
What type of force does the carbon of a carboxylic acid?
London-type interactions.
What are melting and boiling points?
They are processes in which intermolecular forces between identical molecules in a pure sample are disrupted.
Larger molecules have ___ boiling/melting points.
Higher
Why do larger hydrocarbons have higher boiling points?
More carbons and hydrogens means a greater surface area possible for van Der Waals interaction, and thus higher boiling point.
Put the following in order of highest boiling points to lowest boiling points.
3-Hexanone (Dipole-Dipole interactions)
Hexanoic Acid (2x Hydrogen bonding)
Hexane (London forces)
3-Hexanol (hydrogen bonding)
Hexanoic Acid (2x Hydrogen bonding)
3-Hexanone (Dipole-Dipole interactions)
3-Hexanol (hydrogen bonding)
Hexane (London forces)
Why do straight chains have higher boiling points?
Why do branched chains have lower boiling point?
Why does 2,2-Dimethylpropane have the highest melting point?
Symmetrical molecules (such as 2,2-dimethylpropane) tend to have higher melting points than similar molecules with less symmetry due to their packing in the solid state. Once in the liquid state they follow the normal trends.
Why do large molecules have higher boiling points?
Larger molecules have more electrons (greater electron density) therefore temporary dipoles
set up more easily therefore stronger intermolecular forces therefore higher b.pt.
Why do molecules with straight chain have higher boiling points?
What is the format for answering IMF questions?
Why does propane have a higher boiling point than methane?
Why does Hexane have a higher boiling point than 2-methylpentane?
Why does Methanol have a higher boiling point than Methane?
