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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