CHEMISTRY-TEXT
8th Edition
ISBN: 9780134856230
Author: Robinson
Publisher: PEARSON
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Chapter 8, Problem 8.25P
Caffeine is the most widely used stimulant psychoactive drug in the United States. It is found naturally in these eds and leaves of some plants such as tea and coffee and can be synthesized in the laboratory. The following structure shows the connections of atoms in caffeine. Add multiple bonds and lone pairs of electrons to draw an electron-dot structure in which the formal charge on all atoms is zero.
(a) How many tone pairs of electrons are in the structure? How many
(b) What types of intermolecular forces are present in a sample of caffeine?
(c) Would you expect caffeine to be a solid, liquid, or gas at room temperature? Explain your reasoning.
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The two compounds nitrogen dioxide and dinitrogen tetraoxide are introduced in Section 3.13.
(a) NO2 is an odd-electron compound. Draw the best Lewis diagrams possible for it, recognizing that one atom cannot achieve an octet configuration. Use formal charges to decide whether that should be the (central) nitrogen atom or one of the oxygen atoms.
(b) Draw resonance forms for N2O4 that obey the octet rule. The two N atoms are bonded in this molecule.
Oxalic acid,
H2C2O4,
a poisonous colorless solid, is found in some vegetables such as spinach and rhubarb. It is present in concentrations well below the toxic limit, so you can't use this as a reason to refuse a helping of spinach. The order of atoms in a molecule of oxalic acid is
HO2CCO2H.
(a) How many unshared pairs of electrons are on each of the carbon atoms?
(b) How many unshared pairs of electrons are on each of the oxygen atoms?
The two compounds nitrogen dioxide and dinitrogentetraoxide are introduced in Section 3.13.(a) NO2 is an odd-electron compound. Draw the bestLewis diagrams possible for it, recognizing that oneatom cannot achieve an octet configuration. Use formal charges to decide whether that should be the(central) nitrogen atom or one of the oxygen atoms.(b) Draw resonance forms for N2O4 that obey the octetrule. The two N atoms are bonded in this molecule.
Chapter 8 Solutions
CHEMISTRY-TEXT
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