Problem Set 1
Chapters 1 and 2
Due: Monday, January 28, 2008 John Dalton (1766-1844) John Dalton's formulation of an
Atomic
Theory in the first decade of the
19th century provided a theoretical basis for understanding
chemical behavior. In addition to defining the Law of
Multiple Proportions, he also formulated the Rule of
Greatest Simplicity, which held that water was a binary
compound, OH. (Note: Dalton did not use our modern symbols,
which came to us from Berzelius,
but rather
circles that were distinguishable
from one another.) Dalton established the combining masses
of H to O in water as ~1:6. This ratio was later refined to
1:8. The Rule
of Greatest Simplicity, which was
at odds with Gay-Lussac's
Law of Combining Volumes of Gases, did not lead to a correct
formulation for the atomic composition of water. Moreover,
although there was agreement regarding the combining masses
of atoms in the first half of the nineteenth century, there
was
disagreement as to the unit mass
of the common atoms encountered in organic chemistry:
hydrogen (1), carbon
(2x6 or 1x12), oxygen (2x8 or
1x16). Since hydrogen was the lightest of the elements, it
was assigned a mass of one, a notion that is unrelated to
today's mass of hydrogen owing to the presence of a single
proton in the hydrogen nucleus. Berzelius's proposal of a
mass scale based upon O = 100 would have worked as well. For a Brief History of Organic Chemistry
(PowerPoint), click
here.
1. Provide the IUPAC name for the alkane
shown below. For a dynamic Jmol version, click
here. 2. Circle and name the functional (in
red)
in each of the following compounds. 3. Draw resonance structures (if they
exist) for the following compounds. Include all formal
charges.
4. For each of the following acids or bases, identify the corresponding conjugate base or acid, whichever is appropriate.
a) NaNH2 (sodamide)b) acetic acid
c) NaOH
d) CH3MgBr
e) C2H5OH
5. Arrange the acids and conjugate acids in
problem #3 in order of decreasing acidity (increasing
pKa).
6. Draw an orbital picture for the monomer,
acrylonitrile (CH2CHCN).
7. A normal alkane, CnH2n+2, is found to have a
vapor density of 3.66 mg/mL at 200oC and 1 atm.. Using the
ideal gas law, determine the structure of the alkane. A
direct
correlation between the vapor density of a
liquid and its molecular weight was recognized in the 19th century.
What two variables had to be the same? Using the ideal gas law,
determine the "molecular weight" of air at 200oC and 1 atm
(this was usually done experimentally.). Show how the two vapor
densities give the molecular weight of the alkane.