The Metric System

The metric system is a system of measurement using units based on the decimal system. Today, in English, it is formally called the International System, abbreviated SI from the original French, Systtme International. The base units of the modern metric system used in general chemistry are given in the following table. From these, you can derive all other units of measure. 

In this chapter, we are concerned only with the base units for length, mass, and temperature and those derived from them. 

Prefix Abbreviation Numerical Value Equivalent Value in Power of Ten 

The prefixes are used to modify the base unit, such as the meter (m), to make larger or smaller units that are more appropriate for a particular use. The most often used units of length in the metric system are shown in the following table. 

Unit of Length Abbreviation Meter Equivalent Power Equivalent 

The metric system was invented in France, in the course of the French revolution. In 1790 Sir John Riggs Miller and the Bishop of Autum, Prince Talleyrand proposed that Great Britain and France should cooperate to equalize their weights and measures, by the introduction of the metric system. 

To focus on the results of these efforts with time, realize that in the UK, only in 1971 the currency was decimalized. The situation complicates that e.g., the US gallon is of a different size in comparison to the UK gallon. So liquid measures of the same name are not of the same size in the US and UK systems. Also that the US ton is 2000 pounds, whereas a UK ton is 2240 pounds. These are also referred to as a short ton and long ton, respectively. 

In 1901, Giorgp showed that it is possible to combine the CGS system with the electric and magnetic units to create a four-dimensional system by adding the ampere or the ohm, to the CGS units [13]. 

Before, in the Gaussian system, the electric permittivity and the magnetic permeability were treated as dimensionless quantities. This caused strange situations in case of electric and magnetic units in the Gaussian system. Thus, the equations in electromagnetism were reformulated. In SI units, the vacuum permittivity so has the unit A s N m and the magnetic permeability /u.q has the unit NA . Observe that. y/e is a reciprocal velocity. 

In 1946, the Conference Gdndrale des Poids et Mesures (CGPM) approved a system, based on meter, kilogram, second, and ampere. Whereas before the cm, a unit with prefix was previously a basic unit, thereafter the kg, also a prefixed unit appeared as basic unit. In 1954, the kelvin and the candela as base units were introduced, and in 1971 the mole appeared as basic unit. 

How many significant figures should the answer in each of these calculations contain  

If you need to brush up on your math skills, refer to the Mathematical Review In Appendix I. 

The answer contains the same number of significant figures as the measurement with the least number of significant figures. 

Additional material on mathematical operations is given in Appendix I, Mathematical Review. Study any portions that are not familiar to you. You may need to do this at various times during the course when additional knowledge of mathematical operations is required. 

Chemical Reactor Analysis and Applications for the Practicing Engineer. By Louis Hicodoic 2012 John Wiley Sons, Inc. Published 2012 by John Wiley Sons. Inc. 

The metric unit of mass, called the gram, was defined as the mass of one cubic centimeter (a cube that is 1/100 of a meter on each side) of water at its temperature of maximum density. The cubic decimeter (a cube 1/10 of a meter on each side) was chosen as the unit of fluid capacity. This measure was given the name liter. 

By the late 1860s, even better metric standards were needed to keep pace with scientific advances. In 1875, the Treaty of the Meter international treaty set up well-defined metric standards for length and mass, and established permanent machinery to recommend and adopt further refinements in the metric system. This treaty, known as the Metric Convention, was signed by 17 countries, including the United States. 

As a result of the Treaty, metric standards were constracted and distributed to each nation that ratified the Convention. Since 1893, the internationally agreed to metric standards have served as the fundamental weights and measures standards of the United States. 

By 1900 a total of 35 nations—including the major nations of continental Europe and most of South America—had officially accepted the metric system. Today, with the exception of the United States and a few small countries, the entire world is using predominantly the metric system or is committed to such use. In 1971 the Secretary of Commerce, in transmitting to Congress the results of a 3-year study authorized by the Metric Study Act of 1968, recommended that the U.S. change to predominant use of the metric system through a coordinated national program. 

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In the U.S., the result will be in inches for the metric system the results will be in meters. The relationship to convert between the two numbering system results is... 

In the metric system, pressure has a unit of newtons per square meter, which is called a pascal (Pa). Although the pascal is the scientific unit and is preferred, pounds per square inch (Ibs/iif) is comnion in the United States. For example, in most of Europe, tire pressure is recorded in pascals (typically 220,000 Pa), whereas tire pressure in American cars is measured in pounds per square inch (typically 32 Ibs/in ). As a point of reference, the pressure that the earth s... 

The resistance when moving one layer of liquid over another is the basis for the laboratory method of measuring absolute viscosity. Poise viscosity is defined as the force (pounds) per unit of area, in square inches, required to move one parallel surface at a speed of one centimeter-per-second past another parallel surface when the two surfaces are separated by a fluid film one centimeter thick. Figure 40.16. In the metric system, force is expressed in dynes and area in square centimeters. Poise is also the ratio between the shearing stress and the rate of shear of the fluid. 

The concept of kinematic viscosity is the outgrowth of the use of a head of liquid to produce a flow through a capillary tube. The coefficient of absolute viscosity, when divided by the density of the liquid is called the kinematic viscosity. In the metric system, the unit of viscosity is called the stoke and it has the units of centimeters squared per second. One one-hundredth of a stoke is a centistoke. 

The English system of units is complicated compared to the metric system. In the English system, the units of mass are pounds-mass (Ibm) and the units of weight are pounds-force (Ibf). By definition, a weight (i.e., force) of one Ibf equals the force produced by one Ibm under the acceleration of gravity. Therefore, the constant, g, which has the same numerical value as g (32.17) and units of Ibm-ft/lbf-sec, is used in the definition of weight ... 

I am proud of this second edition. For one, I received input/feedback from our valued clients, industry FCC gurus, as well as my colleagues at RMS Engineering, Inc. Each chapter was reviewed carefully for accuracy and completeness. In several areas, 1 have provided additional discussions to cover different FCCU configurations and finally, both the metric and English units have been used to make it easier for readers who use the metric system. 

Data selected from Changing to the Metric System, Metals and Materials, Inst, of Metallurgists, 370, Dec. <1968). 

Scientific measurements are expressed in the metric system. As you know, this is a decimal-based system in which all of the units of a particular quantity are related to one another by factors of 10. The more common prefixes used to express these factors are listed in Table 1.2 (page 7). 

The standard unit of length in the metric system is the meter, which is a little larger than a yard. The meter was originally intended to be 1/40,000,000 of the earth s meridian that passes through Paris. It is now defined as the distance light travels in 1/299,792,458 of a second. 

In the metric system, mass is most commonly expressed in grams, kilograms, or milligrams ... 

As you can see from this discussion, a wide number of different units can be used to express measured quantities in the metric system. Ibis proliferation of units has long been of concern to scientists. In 1960 a self-consistent set of metric units was proposed. This so-called International System of Units (SI) is discussed in Appendix 1. The SI units for the four quantities discussed are... 

The unit of land measure in the English system is the acre, while that in the metric system is the hectare. An acre is 4.356 X 104 ft2. A hectare is ten thousand square meters. The town of Willington in Connecticut requires a minimum area of 2.0 acres of land for a single-family dwelling. How many hectares are required ... 

A lap in most tracks that use the English system is 0.25 mi (English lap). In countries that use the metric system, a metric lap is 0.50 km. A champion marathon runner covers a mile in about 5.0 min. How many minutes will the runner take to run an English lap at that speed A metric lap ... 

Decimals are used in the metric system. A decimal is a fraction in which the denominator is 10 or some power of 10. For example, 2110 (read as two tenths) is a fraction with a denominator of 10 1/100 (read as one one hundredth) is an example of a fraction with a denominator that is a power of 10 (ie, 100). 

The metric system uses decimals (or the decimal system). In the metric system, the gram is the unit of weight, the liter the unit of volume, and the meter the unit of lengtii. 

Display 3-1 lists the measurements used in the metric system. The abbreviations for the measurements are given in parentiieses. 

There are three systems of measurement of drug dosages die metric system, the apothecaries system, and household measurements. The metric system is die most commonly used system of measurement in medicine A physician may prescribe a drug dosage in die apotiiecaries system, but for die most part this ancient system of measurements is only occasionally used. The household system is rarely used in a hospital setting but may be used to measure drug dosses in the home... 

Fractions are not used in the metric system therefore, tiie fraction must be converted to a decimal by dividing tiie denominator into the numerator, or 3 -s- 5 = 0.6 or... 

Under certain circumstances, it may be necessary to compute an oral drug dosage because the dosage ordered by the physician may not be available, or the dosage may have been written in the apothecaries system and the drug or container label is in the metric system. 

The Systeme Internationa] (SI) is the internationally accepted form and elaboration of the metric system. It defines seven base units in terms of which all physical quantities can be expressed. At this stage all we need are ... 

SI (Systeme International) The International System of units a collection of definitions of units and symbols and their deployment. It is an extension and rational ization of the metric system. See also Appendix IB. side chain A hydrocarbon substituent on a hydrocarbon chain. 

Those familiar with the metric system should substitute kilograms for pounds in this example. 

In general, English units will be used throughout this book, with metric units given in parentheses. However, where metric units are the accepted practice, only these will be given. Only English units will be used in the examples, since the metric system has not yet been adopted by the chemical industry in the United States or Canada. 

Scientists measure many different quantities—length, volume, mass (weight), electric current, temperature, pressure, force, magnetic field intensity, radioactivity, and many others. The metric system and its recent extension, Systeme International d Unites (SI), were devised to make measurements and calculations as simple as possible. In this chapter, length, area, volume, and mass will be introduced. Temperature will be introduced in Sec. 2.7 and used extensively in Chap. 11. The quantities to be discussed here are presented in Table 2-1. Their units, abbreviations of the quantities and units, and the legal standards for the quantities are also included. 

The metric system was designed to make calculations easier than using the English system in the following ways ... 

Beginning students often regard the metric system as difficult because it is new to them and because they think they must learn all the English-metric conversion factors (Table 2-3). Engineers do have to work in both systems in the United States, but scientists generally do not work in the English system at all. Once you familiarize yourself with the metric system, it is much easier to work with than the English system is. 

One of the main advantages of the metric system is that the same prefixes are used with all quantities, and they always have the same meanings. 

The older version of the metric system uses the liter as the basic unit of volume. It is defined as 1 dm3. Chemists often use this unit in preference to the m3 because it is about the magnitude of the quantities with which they deal. The student has to know both units, and the relationship between them. 

SI (Systeme International d Unites) a modern version of the metric system. significant digits significant figures. 

Cubic Meter (m3) A measure of volume in the metric system. 

The metric system, which is federally mandated and appears in the official listing of drugs in the United States Pharmacopoeia (USP), is a logically organized system of measurement. It was first developed by the French. The basic units multiplied or divided by 10 comprise the metric system. Therefore, a knowledge of decimals, reviewed in Chapter 1, is useful for this system. 

In the metric system, the three primary or fundamental units are the meter for length, the liter for volume, and the gram for weight. In addition to these... 

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