31.
a. Propane, C3H8
b. Pentane, C5H12
32. The
suffix -ane indicates that hexane is an alkane.
33. Yes,
each of these molecules is an isomer of the other. They all have of 5 carbon
atoms and 12 hydrogen atoms, but appear to be different because of the
arrangement of those atoms. These three molecules are structured isomers of one
another, for they have identical molecular formulas but different arrangements
of atoms.
34. See
drawing.
35.
Butane (C4H10) is the shortest-chain alkane that can demonstrate isomerism-
alkanes with four or more carbon atoms can be demonstrated as straight-chain
structures, branched-chain structures, and ring structures.
36. Both
representations are correct because of their different arrangements of atoms
that do not change the identical molecular formulas of the molecule. This would
make the molecules structural isomers of each other.
37.
a. See drawing.
b. The branched-chain molecule
would have the lower boiling point. Since the straight-chain molecule has
greater molecule-to-molecule contact, it has a stronger intermolecular force
than the branched-chain molecule, resulting in a higher boiling point.
38.
a. A short, straight chain would
have a lower boiling point because of decreased molecule-to-molecule contact
than the longer boiling point. The bonds of this chain would be easier to break
than a longer straight chain.
b. A short, branched chain would
have the lower boiling point. Although the bonds of a branched chain are easier
to break than those of a straight chain, it would be more difficult to break
more molecular bonds within the long chain, resulting in a higher boiling
point.
c. A short, branched chain would
have a lower boiling point. Straight chains have stronger intermolecular forces
that hold together each molecule in contact; where as bonds between branched
chains are more breakable due to the decreased intermolecular molecular forces
between them.
1.
Petroleum is sometimes considered "buried sunshine" because as a
fossil fuel, it originates from biomolecules of prehistoric plants and animals.
The energy released by burning petroleum represents energy originally captured
from sunlight by these prehistoric green plants during photosynthesis; "buried
sunshine".
2.
a. Potential energy is energy of
position, or stored energy ready to be released. An example of potential energy
is the energy within an unreleased winded up spring toy.
b. Kinetic energy is energy related
to motion. A car rolling down a hill is an example of kinetic energy.
3.
Chemical energy, another form of potential energy, is stored within the bonds
in chemical compounds. When an energy-releasing reaction takes place, the bonds
break and reactant atoms reorganize to form new bonds and release energy. If
more energy is released than originally started with, the reaction is
exothermic, but if less energy is released than originally started with, the
reaction is endothermic.
4. A
molecule of butane has more potential energy; it has more carbons than methane
and a higher boiling point than methane. The bonds of butane are harder to
break than the bonds of methane, resulting its higher potential energy.
5.
a. Potential
b. Potential
c. Kinetic
d. Potential
e. Kinetic
6.
Energy is required to break chemical bonds because it is what causes the
reactant bonds to break and reorganize to form new bonds and energy.
7.
a. Exothermic energy is released
than is required to begin the chemical reaction.
b. Endothermic energy is required
to crack large hydrocarbon molecules than is released.
c. Endothermic takes more energy to
digest a candy bar than the energy released after digestion.
8. The
product of a burning candle yields more energy than the energy to begin the
reaction with an unlit candle. Since more energy is let off than required to
begin the reaction, burning a candle is an exothermic reaction.
9. See
drawing.
10. The
law of conservation of energy states that energy is neither created nor
destroyed in any mechanical, physical, or chemical processes.
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