3SAS #1-30 (except for #2, #4, #9, #14, #24, and #25), pages 233-235

1) What is a hydrocarbon?

A hydrocarbon is a molecular compound that only contains atoms of hydrogen and carbon.

3) What characteristics of petroleum make it a valuable resource?

Since petroleum is not only a nonrenewable resource, but a very versatile material that is used both as fuel that can be converted to gasoline, can be used as heat sources, can deliver energy to generate electricity, can generate energy, and is also used to produce useful every day products, it is a valuable resource.

5) What is meant by saying that oil is crude?

Oil is crude because it is pumped from underground and cannot be used in its natural state without some degree of refinement where it is separated into simpler mixtures (through fractional distillation).

6) On average, the United States uses about 20 million barrels of petroleum daily:
a. What is the average number of barrels of petroleum used daily in the United States for building (nonfuel) purposes?
b. How many barrels of petroleum, on average, are burned as fuel daily in the United states?

a. 0.11 x 20,000,000= 2,200,000 barrels
b. 0.89 x 20,000,000= 17,800,000 barrels

7) Name several fuels obtained from crude petroleum.

Heating and cooking fuel, petrochemicals, kerosene, refined oils, gas oil, heavy furnace oil, diesel fuel oil, lubricating oil and grease, heavy oils and wax, cracking stock, petroleum jelly, road oils and asphalt, petroleum coke.

8)
a. List four household items made from petroleum.
b. What materials could be substituted for each of these four household items of petroleum were not available to make them?

a. Water bottle, sports equipment, clothing, artificial limbs.
b. A water bottle can be made out of aluminum, bamboo can be used to make light, flexible, and durable sports equipment, clothing can be made of cotton, and artificial limbs can be made of iron (although it is much better to make them out of plastic).

10)
a. Which world region has the most petroleum reserves relative to its population?
b. Which region has the least petroleum reserves relative to its population?

a. The Middle East has the most petroleum reserves relative to its population.
b. Central Asia, Far East, and Oceania have the least petroleum reserves relative to its population.

11)
a. Which regions consume a greater proportion of the world's supply of petroleum than they possess?
b. Which regions consume a smaller proportion of the world's supply of petroleum than they possess.

a. North America, Central Asia, Far East, and Oceania, Western Europe, and Eastern Europe consume a greater proportion of the world’s supply of petroleum than they possess.
b. The Middle East, Africa, and Central and South America consume a smaller proportion of the world’s supply of petroleum than they possess.

12) Under what conditions could density be used to separate two different liquids?

Density can be used to separate two different liquids if the substances are insoluble with each other.

13) Referring to Table 3.1 (page 216), a mixture of which two of the substances listed would be the easiest to separate from each other by distillation? Explain your reasoning.

Water and acetone would be the easiest to separate from each other by distillation. This is because since water has the highest boiling point, and acetone has the lowest of the four substances, water and acetone would separate fairly quickly and easily by distillation.

15) Referring to Table 3.1 (page 216), sketch a graph of the distillation of a mixture of acetone and water. Label its key features.

16) How does fractional distillation differ from simple distillation?

Fractional distillation does not separate each compound in crude oil, but produces several distinctive mixtures, called fractions. Fractional distillation is also a continuous process. The crude oil is heated in a furnace and then pumped into the fractionating tower. The temperature within the tower (distilling column) is highest at the bottom and decreases towards the top. Smaller and lighter molecules that have lower boiling points vaporize to the top of the tower, and fractions with larger molecules with higher boiling points condense back to liquid in trays in the lower part of the column. Substances with the highest boiling points never vaporize, but drain from the base—bottoms.

17) Petroleum fractions include light, intermediate, and heavy distillates and residues. List three useful products derived from each of these three fractions.

Light: Aviation gasoline and motor gasoline, kerosene, and refined oils.
Intermediate: Gas oil, petrochemicals, heavy furnace oil, and diesel fuel oil.
Heavy: Lubricating oil and grease, heavy oils and wax, and cracking stock.

18) Where in a distillation tower--top, middle, or bottom--would you expect the fraction with the highest boiling point range to be removed? Why?

The fraction with the highest boiling point range would be removed at the bottom. This is because they are thick (viscous) liquids that never vaporize, called bottoms; they drain from the tower’s base.

19) After a fractional distillation, each fraction is still a mixture. Suggest a way to further separate the components of each fraction.

A way to further separate the components of each fraction would be through distillation after a fractional distillation.

20) Rank the following straight-chain hydrocarbons from their lowest boiling point to their highest: hexane (C6H14), methane (CH4), pentane (C5H12), and octane (C8H18). Explain your ranking in terms of intermolecular forces.

Methane (CH4), pentane (C5H12), hexane (C6H14), octane (C8H18).
The boiling points increase with greater amounts carbon atoms within the straight-chains of hydrocarbons; the higher the boiling point, the stronger the intermolecular forces are between the molecules.

21) What is a covalent bond?

A covalent bond is the sharing of two or more valence electrons between two atoms, allowing both atoms to fill their outer shells completely.

22) Why do atoms with filled outer electron shells not form covalent bonds?

Atoms with filled electrons (8 valence electrons) are particularly stable, and therefore, tend to be chemically uncreative. Noble gases are atoms with filled outer electron shells.

23) It has been suggested that a covalent bond linking two atoms is like two dogs tugging on the same sock. Explain how this analogy describes the way that shared electrons hold together atoms in a covalent bond.

Since the two dogs desire the sock, they must share it, although they desire to have it for themselves; like repelling electrons, the dogs pull away from each other, but are still connected by the bond they share with the sock connecting them.

26)
a. What information does a structural formula convey that a molecular formula does not?
b. In what ways is a structural formula an inadequate representation of an actual molecule?

a. A structural formula shows the makeup of a molecule, as well as how high the boiling point is, where as a molecular formula just shows the amount of atoms each element in the formula possesses.
b. The structure of a formula shows how strong molecular bonds within the formula is, as well as the boiling point of the formula.

27) Choose a branched six-carbon hydrocarbon molecule.
a. Draw a Lewis dot structure to represent its structure.
b. Draw a structural formula for the same molecule.

a & b: see drawings.

28) Each carbon atom has six total electrons. Why, then, does the electron-dot representation of a carbon atom show only four dots?

The electron-dot representation of a carbon atom only shows four dots because the four dots represent the valence electrons, located on the outer (and not inner) shell of the atom, where two electrons are located.

29) Use the general molecular formula to write the molecular formula for an alkaline containing
a. 9 carbons.
b. 16 carbons.
c. 10 carbons.
d. 18 carbons.

a. C9H20
b. C16H34
c. C10H22
d. C18H38

30) Calculate the molar mass of each alkane listed in Question 29.

a. 128g
b. 226g
c. 142g
d. 254g