Common units of measure

Viruses are smaller than cells, ranging in size from 0.02 pin to 0.3 pm. A common unit of measure for viruses is the nanometer (abbreviated nm), which is 1000 times smaller than a pm and one million times smaller than a millimeter. 

When measuring acidity in foods and beverages there are two common units of measurement titratable acidity and pH. There is no direct relationship between pH and titratable acidity, therefore, both must be measured experimentally. Titratable acidity (TA), also referred to as total acidity, measures the total acid content in a food or beverage system and is determined by titration of the acids in the food system with a standard base. 

The common unit of measurement for natural gas is the standard cubic foot in the English system and the standard cubic meter in the metric system. Each of these standards is expressed at pressures and temperatures commonly used as standard to the system in the geographical area of concern. In the United States, where standards frequently vary from state to state, the cubic foot is frequently expressed in the English system at standard conditions of 14.73 pounds per square inch absolute (psia) and 60 degrees Fahrenheit (60°F), although there are a number... 

Another common unit of measurement for natural gas is by use of its heating value, expressed in British thermal units (BTU) per standard cubic foot in the English system, and in Joules (or calories) per unit volume in the metric system. Commercially used natural gas, after processing, yields the equivalent of about 950-1050 BTU/ft3. Also used as a unit of measurement is the therm, equivalent to 100,000 BTU, or the nominal heat content of 100 standard cubic feet of lean, processed natural gas. 

The most common unit of measurement in the English system is the mcf or thousand (103) cubic feet. Larger volumes, used to express production or pipeline volumes, are noted as bcf, or billion (109) cubic feet. Even larger volumes, such as reserve figures, usually are expressed as tcf, or trillion (1012) cubic feet. 

Quantitative calculations and qualitative interpretations are fundamental to fully grasp the concepts of chemistry. Quantitative values must include a number and a unit. Two common units of measurement are the conventional (English) system and the metric system. The conventional set of units includes inches, feet, miles, gallons, and pounds. These units, although common in the United States, are not used in science or by most of the world. However, the metric system is becoming more common in the United States. The metric system s base-10 units are easier to use and essential for scientific calculations. However, because most readers of this book are more familiar with the conventional system, it will be necessary to convert to and from the metric system. 

The most common use that chemists make of numbers is to report values for measured quantities. Specification of a measured quantity generally includes a number and a unit of measurement. For example, a length might be given as 12.00 inches (12.00 in) or 30.48 centimeters (30.48 cm), or 0.3048 meters (0.3048 m), and so on. Specification of the quantity is not complete until the unit of measurement is specified. For example, 30.48 cm is definitely not the same as 30.48 in. We discuss numbers in this section of the chapter, and will use some common units of measurement. We discuss units in the next section. 

Other common units of measure include drug spending as a percentage of total health expenditure this gives a relative indication of resource use within the health sector. When examining this measure over time, it is important to distinguish rises and falls in health expenditure generally from rises and falls in pharmaceutical expenditure the two may not run parallel. 

The basic unit in the SI pressure system is a Pascal (Pa), which represents the force exerted by a Newton (N) on a square meter (m ) of surface N/m. The most common units of measure are atmosphere and bar (0.98693 atm = 1 bar). The basic unit of pressure in the English Engineering... 

The basic metric unit of volume is the liter (L), which is defined in terms of metric units of length. As shown in Figure 1.10, a liter is the volume of a decimeter cubed, that is, 1 L = 1 dm (a dm is 0.1 m, about 4 inches). A milliliter (mL) is the same volume as a centimeter cubed (cm or cc—although this latter abbreviation should no longer be used), and a liter is 1000 cm A kiloliter, or cubic meter (m ), is a common unit of measurement for the volume of air. For example, standards for... 

Abbreviations Common units of measurement and other commonly abbreviated terms and designations should be abbreviated as listed below if any others are used often in a manuscript, they should be written out the first time used, followed by the normal and acceptable abbreviation in parentheses [e.g., Acceptable Daily Intake (ADI), Angstrom (A), picogram (pg)]. Except for inch (in.) and number (no., when followed by a numeral), abbreviations are used without periods. Temperatures should be reported as °C or °F (e.g., mp 41° to 43 °C). Because the metric system is the international standard, when pounds (lb) and gallons (gal) are used the metric equivalent should follow in parentheses. 

Usually the first powder characteristic that we are concerned about in our laboratory is specific surface area (more commonly referred to simply as surface area.) The surface area of a powder is a measure of its size, shape, and irregularity (such as the presence of voids that are open to the surface). There are several excellent books about surface area and its measurement.The most commonly used technique for determining powder surface area is the BET method using the adsorption of a monolayer of a gas such as nitrogen on the powder surface. The common unit of measure for surface area is mVg (area/unit mass). Most powders fall in the range of 1 to 50 mVg, with the vast majority of highly sinterable powders falling between 5 and 15 mVg. 

International Standard Unit of measurement whose consistent value is recognized as a common unit of measurement by international agreement. 

Table 21.1 shows the common units of measurements used in the study of gases. 

The common unit of measurement for natural conditions are specified by various regulatory ... 

Another common unit of measurement for natural gas is its heating value, expressed in British thermal units (Btu) per cubic foot in the English system, and in Joules or calories in the metric system. Commercially used natural... 

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