4. Translate into Russian: The Physics of Oil Refineries

Covalent bonds form when two atoms share a pair of electrons. These electrons orbit back and forth between the atoms, reducing both their electrostatic potential ener­gies and their kinetic energies. The reduced kinetic energy of the electrons is a quantum physical effect.

Covalent bonds are quite direction because an atom forming them is trying to com­plete a spherical shell of electrons. The shell for most atoms contains four pairs of elec­trons so that many atoms connect to their neighbors in tetrahedral arrangements.

Double covalent bonds involve the sharing of two separate pairs of electrons be­tween two atoms. The first pair orbits in a path located between the two nuclei but the second pair orbits on either side of the line between atoms. Two atoms cannot swivel about the double bond as they can about a single bond.

A free radical is a molecular fragment in which one or more atoms has an unpaired electron and does not have a complete electronic shell. A free radical is quite reactive and attacks other atoms and molecules in order to complete all of its shells.

The carbon atoms in an aromatic ring are held together by one and a half covalent bonds. The first bond is an ordinary covalent bond with a pair of electrons located between the nuclei but the half bond involves electrons that circulate around the ring, above and below the lines between nuclei.

Most non-polar molecules are held together as liquids or solids by weak van der Waals forces. These forces are created by brief fluctuations in the charged distributions of the molecules. These fluctuations create temporary electrical dipoles in these mol­ecules that tend to attract them toward one another when they are very close together.

Van der Waals forces are not very directional and allow molecules to slide past one another relatively easily.

Molecules at the surface of a liquid have no neighbors on one side with which to bind. As a result, they pull together and create a surface tension. This tension is most severe when the molecules in the liquid exert very large forces on one another. Surface tension tends to minimize the surface of a liquid, shaping it into a flat surface or a sphere whenever possible.

Two liquids such as oil and water, that use very different forces to hold their mol­ecules together, tend to be immiscible. The molecules of each liquid keep to themselves because they are unable to bind strongly to one another. In contrast, liquids such as water and alcohol that bind together in very similar ways tend to be miscible. They mix to form a single, homogeneous liquid. In short, like dissolves like.

5. Discussion of the refinery process. Prepare the brief report on one of the theme topics.

ADDITIONAL MATERIALS:

1. Translate the following sentences:

All different hydrocarbon chain lengths have progressively higher boiling points, so they can all be separated by distillation. This is what happens in an oil refinery - in one part of the process, crude oil is heated and the different chains are pulled out by their vaporization temperatures. Each different chain length has a different property that makes it useful in a different way.

To understand the diversity contained in crude oil, and to understand why refining crude oil is so important in our society, look through the following list of products that come from crude oil:

• Petroleum gas - used for heating, cooking, making plastics

• small alkanes (1 to 4 carbon atoms)

• commonly known by the names methane, ethane, propane, butane

• boiling range = less than 104 degrees Fahrenheit / 40 degrees Celsius

• often liquified under pressure to create LPG (liquified petroleum gas)

• Naphtha or Ligroin - intermediate that will be further processed to make

gasoline

• mix of 5 to 9 carbon atom alkanes

• boiling range = 140 to 212 degrees Fahrenheit / 60 to 100 degrees Celsius

• Gasoline - motor fuel

• liquid

• mix of alkanes and cycloalkanes (5 to 12 carbon atoms)

• boiling range = 104 to 401 degrees Fahrenheit / 40 to 205 degrees Celsius

• Kerosene - fuel for jet engines and tractors; starting material for making other products

• liquid

• mix of alkanes (10 to 18 carbons) and aromatics

• boiling range = 350 to 617 degrees Fahrenheit /175 to 325 degrees Cel­sius

• Gas oil or Diesel distillate - used for diesel fuel and heating oil; starting ma­terial for making other products

• liquid

• alkanes containing 12 or more carbon atoms

• boiling range = 482 to 662 degrees Fahrenheit / 250 to 350 degrees Cel­sius

• Lubricating oil - used for motor oil, grease, other lubricants

• liquid

• long chain (20 to 50 carbon atoms) alkanes, cycloalkanes, aromatics

• boiling range = 572 to 700 degrees Fahrenheit / 300 to 370 degrees Celsius

• Heavy gas or Fuel oil - used for industrial fuel; starting material for making other products

• liquid

• long chain (20 to 70 carbon atoms) alkanes, cycloalkanes, aromatics

• boiling range = 700 to 1112 degrees Fahrenheit / 370 to 600 degrees Cel­sius

• Residuals - coke, asphalt, tar, waxes; starting material for making other products

• solid

• multiple-ringed compounds with 70 or more carbon atoms

• boiling range = greater than 1112 degrees Fahrenheit / 600 degrees Celsius You may have noticed that all of these products have different sizes and boiling

ranges. Chemists take advantage of these properties when refining oil.