Chemistry - Homestead



Chemistry The Metric System

(Author? Source? 1994?)

Mathematically challenged Americans who fear a conversion to the metric system are worrying needlessly.

So says a St. Louis resident who went through a national conversion to metrics in Australia and had to reconvert to the old system when she moved to this country.

She is Gail Ratcliff, chairman of the mathematics and computer science department at the University of Missouri at St. Louis. Obviously, she is anything but mathematically challenged, but even so, she thinks switching to the metric system would be easy for almost everyone.

For one thing, Ratcliff said, the metric system is based on the figure 10, just like the American monetary system. That makes it much simpler than the system based on 12 inches to a foot, 3 feet to a yard, 16 ounces to a pound, 2 pints to a quart and the rest of our mathematically muddled measurements.

Born and reared in Australia, she came to the United States to do graduate work at Yale University and then took a teaching job at UMSL 11 years ago.

Australians went through two major changes of a mathematical nature, first in the mid-1960s, switching from a British monetary system of pence, shillings and pounds to an American-style system of dollars and cents. A few years later, they adopted the metric system for all measurements.

"It went very smoothly," Ratcliff said. "There was a transition period. At first, the highway signs had dual terms – both miles and kilometers – but after a few years, they were replaced by ones with just kilometers."

Probably, she added, some people had worried about coping with new terms for buying products like groceries.

"But they soon realized the one kilogram was equal to about two pounds, so if they wanted to buy a pound of steak, they would just ask for a half-kilo," she said.

"Everyone found it wasn't such a painful process. They soon threw away the conversion tables and became totally accustomed to the new system."

What was hard to accept, Ratcliff noted, was the change in measurements for height and weight. To those used to expressing their heights in feet and their weights in pounds, the metric terms sound strange.

In Australia before the change to the metric system people had described their weights by using the British measurement based on the "stone" – one stone equals 14 pounds – and most older people have continued to use that, she said.

Asked why she thinks Americans are so resistant to the metric system, Ratcliff said "probably a little bit of math phobia" is one reason. Also, she said, many people fear they won't understand the mathematical units they would have to deal in, when making purchases and conducting other types of business.

But such fears are based on a total misunderstanding of how basically simple the metric system is to understand and use, she said.

One of Ratcliff's colleagues at UMSL, Harold Harris, professor of chemistry, says adoption of the metric system by the United States is "far overdue." He is chairman of the St. Louis section of the American Chemical Society.

Like all scientists, he used the metric system daily in his work.

"It's the only choice," he said. "The language of science is the metric system. It's also the natural choice; it's logical and convenient."

Harris said that most American schoolchildren now are being taught the metric system, so young people should find a switch to that system easier than the older generation will. Also, he added, young people use metric terms in many spots, especially track and field events.

This country is easing into adoption of the metric system by metric labels on many products, Harris noted. A change to metrics by the United States probably would be welcomed by car manufacturers, he said, since it would simplify worldwide auto sales.

Eventually, Harris declared, this country will have to adopt the metric system – "It's just a matter of time."

FTC Rule Will Drag U.S. Into The World Of Grams and Liters

by Randolph E. Schmid of The Associated Press.

Metric measurements are inching their way onto more American product labels.

Federal Trade Commission rules that went into effect Feb. 21 require that new labels printed for consumer products include metric as well as the English units customarily used on American products.

Manufacturers will be allowed to use up their old supplies of labels, so it may be a while before the label change becomes obvious.

Products covered by the rule include such items as soap, toilet paper, tissues, foil wrap, plastic bags, detergents, mops, deodorants, shampoo, batteries and light bulbs, explained Robert E. Eaton of the commission.

Labeling a bar of soap, for example, as 5 ounces will no longer be good enough; the label will have to include the fact it weighs 141 grams.

Food and Drug Administration labeling rules to require the addition of metric measurements on foods, drugs and cosmetics are under development.

William G. Moren of the National Association of Manufacturers said the change should cause few problems.

There have been a few complaints about the cost of change, he said, "but in the long run it just makes sense if you are going to compete in international markets … which is virtually a given if you want to stay in business."

Indeed, only the United States, Burma and Liberia still use the system of feet, gallons and pounds, the U.S. Metric Association reports.

Many products already include metric measurements, especially alcoholic beverages and soft drinks, which have become familiar in metric bottle in recent years.

FTC officials expect the new labeling requirements to have little impact on manufacturers since they can use old labels. In addition, the agency said it will not take any action to enforce the dual-labeling requirement until Nov. 8.

The FTC said that all the rule requires is the manufacturers make simple mathematical conversions from the inch-pound system to the metric system and include the metric equivalents on the already required labeling for consumer products.

The move is the latest step under the Fair Packaging and Labeling Act, which also requires that a product label disclose the contents of the package.

While some products have carried metric labeling for years, a recent congressional report said the process of moving the United States into the metric system has been grindingly slow, despite a 1988 law requiring federal agencies to eventually adopt metrics in procurement and construction – even highway signs.

Resistance to conversion remains strong in private industry, because of the cost, and among a public fearful of confusing change

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Metric Prefixes

Prefixes on metric units signify that they are multiplied by the corresponding number in this chart. Example: When you read that the United States has 630 gigawatts of electric generating capacity, that means 630 billion watts.

1,000,000,000,000,000,000 exa (E) quintillion

1,000,000,000,000,000 peta (P) quadrillion

1,000,000,000,000 tera (T) trillion

1,000,000,000 giga (G) billion

1,000,000 mega (M) million

1,000 kilo (k) thousand

100 hecto (h) hundred

10 deka (da) ten

1

0.1 deci (d) tenth

0.01 centi (c) hundredth

0.001 milli (m) thousandth

0.000 001 micro (() millionth

0.000 000 001 nano (n) billionth

0.000 000 000 001 pico (p) trillionth

0.000 000 000 000 001 fenti (f) quadrillionth

0.000 000 000 000 000 001 atto (a) quintillionth

SI Units (International System of Units, or in French Le systeme Internationsl d'Unites).

Definitions and conversions

Meter: (m) unit of length.

Originally pegged at 1/40,000,000th of the Earth's girth, it is now defined by scientists in terms of the wavelength of a certain kind of light. One meter = 1 yard plus 3.37 inches.

Kilogram (kg) unit of mass.

The kilogram is officially defined as the mass of a chunk of platinum-iridium ally stored in a vault in Sevres, outside Paris. It was originally defined as the weight of 1,000 cubic centimeters (one liter) of water, which is still a useful definition for everyday purposes. One kilogram = 2 pounds, 3 ounces.

Second: (s) unit of time.

The second is defined by scientists in terms of the number of vibrations of a cesium atom. One second = 1/60th of a minute.

Kelvin: (K) unit of temperature.

It is identical to the Celsius degree except the starting point is absolute zero, 273 Celsius degrees (492 Fahrenheit degrees) below freezing. The boiling point of water is 373 K.

Ampere: (A) unit of electric current.

It is technically defined as the current which, if flowing through two parallel wires a meter apart, would produce a specified force between them.

Mole: (mol) unit of quantity.

It is the weight in grams of a pure substance composed of 602,213,670,000,000,000,000,000 elementary particles.

Candela: (cd) unit of luminous intensity.

It is the SI-approved name for candlepower.

All other SI units are derived from the basic seven. Here are some examples:

Centimeter (cm) = 1/100th of a meter. There are 2.54 centimeters to the inch.

Millimeter (mm) = 1/10th of a centimeter or 1/1000th of a meter. There are 25.4 millimeters to the inch.

Cubic Centimeter (cc or cm3) is a unit of volume. Five cc's make a teaspoonful, approximately.

Gram (g) = 1/1000th of a kilogram. It is the weight of one cubic centimeter of water. It is a bit less than 1/28th of an ounce – about the mass of a paper clip.

Liter (L) = 1,000 cc's. It is about 5.7 percent larger than a quart.

Newton (N) is the SI measure of force. An apple in a tree exerts a downward pull on the branch of about two newtons.

Chemistry Name ______________________________

The Metric System Articles Worksheet Period _____ Date ___________________

1) Why is the metric system easier to use?

2) One kilogram = approximately _____ pounds.

3) What are Americans so resistant to the metric system?

4) The metric system is the language of ___________________.

5) Young people (already) use metric terms in many sports, especially _______________________________.

6) This country is easing into the adoption of the metric system by doing what?

7) Give the word that is associated with each prefix (example: deci- = tenth).

a) mega- =

b) centi- =

c) kilo- =

d) milli- =

7) Originally, the meter was pegged at what fraction of the Earth's girth?

8) Which is longer, a meter or a yard?

9) If one yard equals 36 inches, one meter equals __________ inches.

10) The kilogram is defined as the mass of __________ of water.

11) One centimeter = __________ meter. There are __________ centimeters to an inch.

12) One gram equals the weight of mass of ________________________________ of water.

13) One millimeter = _________ meter, or __________ centimeter.

14) One liter is 5.7% __________ than the quart, and is __________cc's.

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