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Chem&219 Unit 5 Questions and Correct
Answers/ Latest Update / Already Graded
Generic formula for alcohols
Ans: R-OH
phenol
Ans: hydroxy-substituted aromatic molecules (any compound
with an -OH attached to a benzene ring)
IUPAC system rules for naming organic alcohols
Ans: - organic alcohols are named by replacing the suffix of the
parent chain of the molecule with the suffix -ol
- The parent chain is numbered so as to give the hydroxyl group
the lowest possible number. (examples: 1 -propanol, and
cyclohexanol)
- with unsaturated alcohols the -ol suffix comes last and takes
priority when numbering the parent chain (2-propene-1-ol)
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- Molecules with more than one -OH group get a prefix
describing the number of -OH groups added to the IUPAC
name. (ethane-1,2-diol)
Molecules with more than one -OH group
Ans: polyols
IUPAC rules for phenols
Ans: - the suffix for an alcohol substituted benzene is "phenol"
- start the numbering at the OH group (so OH is at the 1
position)
(examples: phenol, 3-methylphenol, 2,4-dinitrophenol)
Why can alcohols form strong hydrogen bonds?
Ans: Due to the presence of the hydroxyl group, as the O -H
bond is highly polarized by the electronegative oxygen atom.
This polarization places a + charge on the hydrogen atom and a
- charge on the oxygen atom. The polarization in the O -H bond
on one alcohol molecule becomes attracted to the polarization
in the O-H bond of another alcohol molecule.
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Why do alcohols have much higher boiling points than other molecules
of similar molecular weight?
Ans: hydrogen bonding between alcohol molecules
These attractions raise the amount of energy required to
vaporize the liquid-phase molecules (boil), which translates into
increased boiling point temperatures.
Alcohol molecules can freely hydrogen bond to other molecules
possessing what groups?
Ans: O-H, N-H, or S-H functional groupings
How does the water solubility of alcohol molecules change as the
molecular weight changes?
Ans: Alcohol molecules of lower molecular weight are mostly
soluble in water as a result of the ability to hydro gen bond to
OH, NH, or SH groups. As the molecular weight or carbon -chain
length increases, the alcohol molecules become
correspondingly less soluble in water.
How do alcohols and phenols act as weak acids and weak bases?
All rights reserved © 2025/ 2026 |
Chem&219 Unit 5 Questions and Correct
Answers/ Latest Update / Already Graded
Generic formula for alcohols
Ans: R-OH
phenol
Ans: hydroxy-substituted aromatic molecules (any compound
with an -OH attached to a benzene ring)
IUPAC system rules for naming organic alcohols
Ans: - organic alcohols are named by replacing the suffix of the
parent chain of the molecule with the suffix -ol
- The parent chain is numbered so as to give the hydroxyl group
the lowest possible number. (examples: 1 -propanol, and
cyclohexanol)
- with unsaturated alcohols the -ol suffix comes last and takes
priority when numbering the parent chain (2-propene-1-ol)
All rights reserved © 2025/ 2026 |
, Page |2
- Molecules with more than one -OH group get a prefix
describing the number of -OH groups added to the IUPAC
name. (ethane-1,2-diol)
Molecules with more than one -OH group
Ans: polyols
IUPAC rules for phenols
Ans: - the suffix for an alcohol substituted benzene is "phenol"
- start the numbering at the OH group (so OH is at the 1
position)
(examples: phenol, 3-methylphenol, 2,4-dinitrophenol)
Why can alcohols form strong hydrogen bonds?
Ans: Due to the presence of the hydroxyl group, as the O -H
bond is highly polarized by the electronegative oxygen atom.
This polarization places a + charge on the hydrogen atom and a
- charge on the oxygen atom. The polarization in the O -H bond
on one alcohol molecule becomes attracted to the polarization
in the O-H bond of another alcohol molecule.
All rights reserved © 2025/ 2026 |
, Page |3
Why do alcohols have much higher boiling points than other molecules
of similar molecular weight?
Ans: hydrogen bonding between alcohol molecules
These attractions raise the amount of energy required to
vaporize the liquid-phase molecules (boil), which translates into
increased boiling point temperatures.
Alcohol molecules can freely hydrogen bond to other molecules
possessing what groups?
Ans: O-H, N-H, or S-H functional groupings
How does the water solubility of alcohol molecules change as the
molecular weight changes?
Ans: Alcohol molecules of lower molecular weight are mostly
soluble in water as a result of the ability to hydro gen bond to
OH, NH, or SH groups. As the molecular weight or carbon -chain
length increases, the alcohol molecules become
correspondingly less soluble in water.
How do alcohols and phenols act as weak acids and weak bases?
All rights reserved © 2025/ 2026 |
