The Foundations of Chemistry

This is a condition (not related to colloids) in which an overgrowth of vegetation is caused

by the high concentration of phosphorus, a plant nutrient. This overgrowth and the subse-

quent decay of the dead plants lead to decreased dissolved O 2 in the water, which causes

the gradual elimination of marine life. There is also a foaming problem associated with

branched alkylbenzenesulfonate (ABS) detergents in streams and in pipes, tanks, and

pumps of sewage treatment plants. Such detergents are not biodegradable;that is, they

cannot be broken down by bacteria.

Currently used linear-chain alkylbenzenesulfonate (LAS) detergents are biodegradable and

do not cause such foaming.

CH 3 CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 SO 3



Na

sodium lauryl benzenesulfonate

a linear alkylbenzenesulfonate (LAS)—a biodegradable detergent

CH 3 CHCH 2 CHCH 2 CHCH 2 CH

CH 3 CH 3 CH 3 CH 3

SO 3



Na

a sodium branched alkylbenzenesulfonate (ABS)—a nonbiodegradable detergent

The two detergents shown here each
have a C 12 H 25 tail but the branched
one is not biodegradable.

582 CHAPTER 14: Solutions

CC Our Daily Lives

HEMISTRY IN USE

Why Does Red Wine Go with Red Meat?

Choosing the appropriate wine to go with dinner is a prob-

lem for some diners. Experts, however, have offered a simple

rule for generations, “serve red wine with red meat and white

wine with fish and chicken.” Are these cuisine choices just

traditions, or are there fundamental reasons for them?

Red wine is usually served with red meat because of a

desirable matching of the chemicals found in each. The most

influential ingredient in red meat is fat; it gives red meats

their desirable flavor. As you chew a piece of red meat, the

fat from the meat coats your tongue and palate, which desen-

sitizes your taste buds. As a result, your second bite of red

meat is less tasty than the first. Your steak would taste bet-

ter if you washed your mouth between mouthfuls; there is an

easy way to wash away the fat deposits.

Red wine contains a surfactant that cleanses your mouth,

removing fat deposits, re-exposing your taste buds, and allow-

ing you to savor the next bite of red meat almost as well as

the first bite. The tannic acid (also called tannin) in red wine

provides a soap-like action. Like soap, tannic acid consists of

both a nonpolar complex hydrocarbon part as well as a polar

one. The polar part of tannic acid dissolves in polar saliva,

while the nonpolar part dissolves in the fat film that coats

your palate. When you sip red wine, a suspension of micelles

forms in the saliva. This micelle emulsion has the fat mole-

cules in its interior; the fat is washed away by swallowing the

red wine.

White wines go poorly with red meats because they lack

the tannic acid needed to cleanse the palate. In fact, the pres-

ence or absence of tannic acid distinguishes red wines from

white wines. Grapes fermented with their skins produce red

wines; grapes fermented without their skins produce white

wines.

Because fish and chicken have less fat than red meats,

they can be enjoyed without surfactants to cleanse the palate.

Also, tannic acid has a strong flavor that can overpower the

delicate flavor of many fish. The absence of tannic acid in

white wines gives them a lighter flavor than red wines, and

many people prefer this lighter flavor with their fish or

chicken dinners.

Ronald DeLorenzo

Middle Georgia College