Cubic meter, measurement unit

Laboratories around the world use the same standardized units of measurements, called the International System of Units, or SI. The SI system has seven base units from which all the others are derived. The base units of this system include a unit of length, meters, and a unit of mass, kilograms. Volume is derived unit and is measured in cubic meters. These units can be described in various sizes. Common divisions of these units are given in Table 1.3. Thus we can measure distance in meters, centimeters or millimeters we can measure weight in kilograms, or micrograms we can measure volume in cubic meters, cubic centimeters, and so on. 

The NAAQS are expressed ia the form of ground level concentrations (GLC), which are the concentrations of pollutant ia the ambient air as measured at ground level, ia units of either micrograms per cubic meter or ppm. In order to convert a source s emission ia kilograms per hour to a GLC, dispersion modeling must be used. 

The viscosity ratio or relative viscosity, Tj p is the ratio of the viscosity of the polymer solution to the viscosity of the pure solvent. In capillary viscometer measurements, the relative viscosity (dimensionless) is the ratio of the flow time for the solution t to the flow time for the solvent /q (Table 2). The specific (sp) viscosity (dimensionless) is also defined in Table 2, as is the viscosity number or reduced (red) viscosity, which has the units of cubic meters per kilogram (m /kg) or deciUters per gram (dL/g). The logarithmic viscosity number or inherent (inh) viscosity likewise has the units m /kg or dL/g. For Tj g and Tj p, the concentration of polymer, is expressed in convenient units, traditionally g/100 cm but kg/m in SI units. The viscosity number and logarithmic viscosity number vary with concentration, but each can be extrapolated (Fig. 9) to zero concentration to give the limiting viscosity number (intrinsic viscosity) (Table 2). 

NOTE Difficulties of accurately characterizing many of the specimens mean that many of the values presented here must he regarded as being of order of magnitude only For some materials, actual measurement may he the only way to obtain data of the required accuracy To convert kilograms per cubic meter to pounds per cubic foot, multiply hy 0.062428 to convert kilojoules per Idlogram-kelvin to British thermal units per pound-degree Fahrenheit, multiply hy 0.23885. 

Tlic density (p) of a substance is tlic ratio of its mass to its volume and may be expressed in units of pounds per cubic foot (Ib/ft ) or kilograms per cubic meter (kg/nv ). For solids, density can be determined easily by placing a known mass of the substance in a liquid and measuring tlie displaced volume. The density of a liquid can be measured by weighing a known volume of the liquid in a gradmitcd cylinder. For gases, tlie ideal gas law (to be discussed in Section 4.6) can be used to calculate tlie density from tlie temperature, pressure, and molecular weight of tlie gas. 

The process of compiling the budgets will start with the preparation of estimates of the physical requirements of the plan, be they manpower, materials, tons of fuel, cubic meters or therms of gas, units of electricity or cubic meters of water. These estimates will be prepared in relation to the estimates of output by manufacturing or process departments, which, in turn, will have been based on the quantities, or other measures forecast in the sales budgets. 

Mass Transfer Rates. Mass transfer occurs across the interface. The rate of mass transfer is proportional to the interfacial area and the concentration driving force. Suppose component A is being transferred from the gas to the liquid. The concentration of A in the gas phase is Ug and the concentration of A in the liquid phase is u . Both concentrations have units of moles per cubic meter however they are not directly comparable because they are in different phases. This fact makes mass transfer more difficult than heat transfer since the temperature is the temperature regardless of what phase it is measured in, and the driving force for heat transfer across an interface is just the temperature difference Tg—Ti. For mass transfer, the driving force is not Ug—ai. Instead, one of the concentrations must be converted to its equivalent value in the other phase. 

A unit of measurement is an agreed-upon standard with which other values are compared. Scientists use the meter as the standard unit of length. The meter was originally chosen to be 10 times the length of a line from the North Pole to the equator. Volume can be measured in pints, quarts, and gallons, but the scientific units are the cubic meter and the liter. Temperature can be measured in degrees Fahrenheit (°F), degrees Celsius (°C), or kelvins (K). 

The international scientific community prefers to work exclusively with a single set of units, the Systeme International (SI), which expresses each fundamental physical quantity in decimally (power of 10) related units. The seven base units of the SI are listed in Table 1-3. The SI unit for volume is obtained from the base unit for length A cube that measures 1 meter on a side has a volume of 1 cubic meter. 

It is often necessary to convert measurements from one set of units to another. As an everyday exampie, traveiers between the United States and Canada need to be abie to convert between miies and kiiometers. Chemists frequentiy need to convert voiumes from one unit to another. The SI unit of voiume is the cubic meter, but chemists usuaiiy work with much smaiier voiumes. Hence chemists often express voiume using the liter (L), which is defined to be exactiy 10 m. Another voiume unit in common use is the miiiiiiter (mL), or 10 L. 

Volatility is the weight of vapor present in a unit volume of air, under equilibrium conditions, at a specified temperature. It is a measure of how much material (agent) evaporates under given conditions. The volatility depends on vapor pressure. It varies directly with temperature. We express volatility as milligrams of vapor per cubic meter (mg/m3). Calculate it numerically by an equation derived from the perfect gas law. This equation follows ... 

To control the emission of organics, these units must comply with similar DRE requirements to the other hazardous waste combustion units. Owners or operators of MACT combustion units must select POHCs and demonstrate a DRE of 99.99% for each POHC in the hazardous wastestream. Sources that bum hazardous waste have a required DRE of 99.9999% for each POHC designated. Additionally, for dioxins and furans, U.S. EPA promulgated more stringent standards under MACT. For example, MACT incinerators and cement kilns that bum waste with dioxins and furans must not exceed an emission limitation of either 0.2 ng of toxicity equivalence per dry standard cubic meter (TEQ/m3) or 0.4 ng TEQ/m3 at the inlet to the dry particulate matter control device. This unit of measure is based on a method for assessing risks associated with exposures to dioxins and furans. 

In SI units MA = 0.1279 kg/mole. If n A is measured in molecules per cubic meter and rAA in molecules per cubic meter per second, the last equation becomes... 

A similar conversion is necessary to measure rAA in kilomoles per cubic meter per second. In these units... 

As we have seen, toxic materials are commonly found as aerosols, that is, floating minute particles within the breathing air, either as gases and vapors or liquids and solids. As we have seen also, gases and vapors are measured in volume units, namely, parts per million (ppm), while liquids and solids are measured in weight units, namely, milligrams per cubic meter. 

Volume, the amount of space occupied by an object, is measured in SI units by the cubic meter (m3), defined as the amount of space occupied by a cube 1 meter on each edge (Figure 1.5). 

Accurate measurement is crucial to scientific experimentation. The units used are those of the Systeme Internationale (SI units). There are seven fundamental SI units, together with other derived units Mass, the amount of matter an object contains, is measured in kilograms (kg) length is measured in meters (m) temperature is measured in kelvins (K) and volume is measured in cubic meters (m3). The more familiar metric liter (L) and milliliter (mL) are also still used for measuring volume, and the Celsius degree (°C) is still used for measuring temperature. Density is an intensive physical property that relates mass to volume. 

In a measurement of air pollution, air was drawn through a filter at the rate of 26.2 liters per minute for 48.0 hours. The filter gained 0.0241 grams in mass because of entrapped solid particles. Express the concentration of solid contaminants in the air in units of micrograms per cubic meter. 

The prefix multipliers increase or decrease the size of the base unit, so that it more conveniently describes the system being measured. The base units that we will be using are listed in Table 1.1. For the purists, it is not strictly correct to include liters as a base unit, because volume is derived from length, and thus the official SI unit of volume is the cubic meter (m3), which is derived from the length base unit, the meter. Chemists frequently express mass in units of grams, which is derived from the kilogram. There are three other SI base units (the mole, the candela, and the ampere). We will consider moles (amount of material) and amperes (electric current) in subsequent chapters. The candela is a unit of light intensity or luminosity and does not concern us at this point. 

This relationship has four quantities. To exactly solve a problem, you need three of the four variables. Boyle s Law is not sensitive to units of pressure or volume. You can measure pressure in units of pascals, psi, atm, or whatever. Likewise, you can measure volume in units of cubic meters (m3), milliliters, or gallons. However, once you have selected a set of units for one side of the equation, you have to use the same units on the other side. 

Since the primary unit of length is the meter, the secondary unit of volume is the cubic meter. In practice, though, the chemical community measures volume in liters and concentration in moles per liter, and often measures temperature in degrees Celsius (labeled °C, not C, to avoid confusion with the abbreviation for charge). Other... 

The SI unit of volume is the cubic meter (m3), but in most scientific applications, volumes are usually measured in cubic centimeters (cm3) or liters (L). One liter contains 1,000 milliliters (mL), or equivalently, 1,000 cm3. 

C For A, the prefix micro— indicates 10-6. 32 micrograms is 0.000032 g. For B, the two measurements do not have the same meaning because they differ in the number of significant figures. 26 nm is 2.6x10-8 m. The symbol "n" for nano— indicates 10-9. For C and D, unit conversions between cubic meters and liters are required. 

The original idea of the metric system was that either approach would provide the same unit of metric volume. Unfortunately, it did not work because of the subtle differences in density caused by subtle differences in temperature. Thus, the kilogram-based milliliter equaled 1.000,027 cubic centimeters. Because of the discrepancy, the International System for Weights and Measures had to make a choice between which approach would be accepted to obtain volume measurements, and the nod was eventually given to the cubic length technique. The use of liters and milliliters in volumetric ware is therefore misleading because the unit of volume measurement should be cubic meters (cubic centimeters are used as a convenience for smaller containers). The International System of Units (SI) and the ASTM accept the use of liters and milliliters in their reports, provided that the precision of the material does not warrant cubic centimeters. Because the actual difference in one cubic centimeter is less than 3 parts in 100,000, for most work it is safe to assume that 1 cm3 is equal to 1 mL. 

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